USMLE 252

The good, the bad, and the ugly! (anticoagulants)

2009-11-04T17:34:00.000-05:00

Warfarin

Uses:

Afib
Mechanical valves
DVT/PE

Overdose:

Bleeding to death: give FFP with will immediately help, and give Vit K (takes a couple days to work)
Just have an elevated INR (no active bleeding):
Hold coumadin
Give Vit k if INR really high

Good:

Oral (means no annoying shots)
Cheap

Bad:

Takes a few days to reach a therapeutic level
Hard to reverse
Hard to regulate

Ugly:

Warfarin skin necrosis (pro-clot situation, happens because protein c and s go
away first leaving factors 10, 9, 7, and 2 unopposed)

Heparin

Uses:

DVT/PE in hospital
AMI
Non-hemorrhagic stroke
DIC
Prophylaxis in hospital

Overdose:

Bleeding to death: protamine sulfate
Elevated PTT: hold heparin
Good:
Quick and cheap
Easy to monitor
Easy to reverse
Can give to preggos

Bad:

IV/Subcut only
Have to give often (you get an subcutaneous injection every 8 hours)
Variable response to same dose

Ugly:

HIT (platelets drop 50% in a few days or get less than 50,000, history of heparin exposure (heparin coated catheters, heparin flushes, put a sign above their bed saying "NO HEPARIN PRODUCTS")
Die from thrombosis (arterial or wacky venous thrombosis)
Treat HIT by withholding ALL heparin products, argatroban, lepirudin. Can never give enoxaparin if already have HIT because it can cause HIT 5% of time.

Enoxaparin

Uses:

AMI
DVT/PE
Preggos w/ DVT

OD:

Active bleeding give FFP
Hold enoxaparin

Good:

Can give to preggos
Longer half life
Don't need to monitor (for a given dose per weight you will get a known result)
Less incidence of HIT

Bad:

$$$$$
Subcut only
Still can cause HIT
Adjust with renal failure

Question Dissection

2009-06-26T20:53:00.003-04:00

Note that you don't need to know what the right answer is. It is easier to disprove the other answers.

Front, back, left and right.

2009-06-25T10:27:00.002-04:00

Knowledge of what heart chamber is most anterior, posterior, left or right is clinically useful. A stab wound to the anterior chest wall is likely to hit the right ventricle. Left atrial enlargement can cause dysphagia due to its posterior location.

This is how I remember the locations of the chambers.

The most anterior chamber is the RIGHT VENTRICLE. To get the most posterior chamber, take the opposite of RIGHT and VENTRICLE. You get LEFT and ATRIA.

The rightmost chamber is the RIGHT ATRIA, which makes the LEFT VENTRICLE, the leftmost chamber.

Big Mac for MAC

2009-06-17T10:56:00.005-04:00

Mycobacterium Avium Complex (MAC) is usually found in HIV+ patients with a CD4 count <50. Prophylaxis against MAC is a MACrolide (clarithromycin or azithromycin). These are used instead of the usual TB drugs to avoid creating drug-resistant TB.

Pathology Review from Pathguy

2009-06-01T12:39:00.002-04:00

Pathology can be a daunting subject to approach. There are a lot of resources but here is a couple links to a really good pathology review. They are from pathguy.com.

Meltdown: General path notes
Boildown: Systemic path notes

Heart Murmurs

2009-05-27T23:32:00.003-04:00

The key to understanding heart murmurs is realizing that:

Systole=ventricle contracting
Diastole=atria contracting or the aortic pressure pushing back on the aortic valve

Murmurs that occur during SYSTOLE:
1. Blood going forward through a narrow aortic valve (aortic stenosis, crescendo-decrescendo)
2. Blood going forward through a ventricular septal defect (VSD, holosystolic)
3. Blood going through a narrowed aortic outflow tract (hypertrophic cardiomyopathy)
4. Blood going back through a leaky mitral valve (mitral regurgitation, holosystolic)

Murmurs that occur during DIASTOLE (remember that diastole is when the atria contract or the aorta pushes back on the aortic valve):
1. Blood going forward through a narrow mitral valve (mitral stenosis)
2. Blood being pushed back through a leaky aortic valve (aortic regurgitation)

The murmur of an atrial septal defect (ASD) is a fixed split S2.

A video is worth a thousand words.

2009-05-22T13:44:00.004-04:00

Let's say you're having a tough time visualizing the fetal circulation in your head and diagrams just aren't cutting it. Google has a cool feature that allows you to search for Flash videos by using the filetype:swf modifier. For example if I wanted flash videos on the fetal circulation, I typed fetal circulation filetype:swf.

Here's a nice flash animation on the fetal circulation that I found with this Google search.

Sloppy Joes!

2009-05-21T19:08:00.003-04:00

Both HCV and HIV are sloppy reproducers, making their structure too variable to create a working vaccine against them.

Neisseria gonorrhea is usually tested on its highly variable pili, which makes it difficult to target with a vaccine.

Inguinal Canal and Hernias

2009-05-12T17:27:00.002-04:00

Check out this flash animation!

Is it Crohn's Disease or Ulcerative Colitis?

2009-03-26T00:23:00.002-04:00

I grew tired of all those annoying tables comparing Crohn's Disease (CD) with Ulcerative Colitis (UC). I've boiled these tables down to a few"rules" to look for in the stem of the question.

1st rule: If the rectum is spared, it's CD. Or another way to put it is that UC will always start from the rectum and move up, without skip lesions.
2nd rule: If there are fistulas, its CD. Remember that CD is transmural.
3rd rule: if it involves the small intestine, its NEVER UC. UC will never move past the ileocecal valve, so if there is terminal ileal involvement, it must be CD.
4th rule: if there are granulomas, its CD.

Hope this helps.

He's get Heinz Bodies!

2009-03-24T08:57:00.004-04:00

X-linked Recessive disorders
("HE's" get x-linked recessive disorders)
Never answer one of these diseases for a woman! If you are going to answer one of these, you should have an upper motor neuron reflex to look at the stem of the question to make sure its a boy.

Fragile X (self explanatory)
Duchenne Muscular Dystrophy (duc"HE"nne)
Becker Muscular Dystrophy
Hemophilia A (Factor VIII) ("HE"mophilia)
Hemophilia B (Factor IX)
Bruton's Agammaglobulinemia (BOYS get Brutons)
Alport's Syndrome (picture a helicopter at the airport landing. The propeller is shaped like an "X")
G6PD Deficiency (he's get "HE"inz bodies)
Lesch-Nyhan Syndrome
Adrenoleukodystrophy
Fabry Disease (Fabr"HE"s disease)
Hunter's Syndrome (hunters aim at an "X")
Menkes Disease (menk"HE"s, Kinky Hair syndrome, copper problem, don't forget Wilson's disease is also a copper problem)
Rett syndrome (Men, who only have one X chromosome, die before they're born, women have 2 x chromosomes so they can survive to exhibit the disease. This is an exception to the rule that only men are affected by XLR diseases. Thanks Keith)
Wiskott-Aldrich Syndrome (triad of eczema, low platelets, and immune deficiency. Don't forget that eczema is a fancy word for an itchy rash.)

M's the letter for Mycoplasma pneumonia

2009-03-19T21:19:00.003-04:00

When you think of mycoplasma, first don't get it confused with mycobacterium!

Then think of the M's

Mycoplasma
Military and Minors
IgM (this causes the infamous cold agglutination which can lead to hemolytic anemia)
Bullous Myringitis (bullae on the tympanic membrane)

My tips for estrogen

2009-02-25T16:56:00.000-05:00

My rule: Estrogen causes growth.

Estrogen comes from 3 main areas: ovaries, adrenal cortex, and placenta.
You should associate FSH with estrogen and LH with progesterone. So a really high FSH usually means that estrogen is low and the FSH is trying to "wake up" the ovaries to release more estrogen. A high FSH is an indicator of menopause when the ovaries have dropped thier production of estrogen.
Estrogen stimulates the growth of breasts, This means too much estrogen in women is associated with breast cancer. In men with cirrhosis, the liver cannot break down the estrogen so this leads to gynecomastia in men.
Estrogen stimulates the growth of the endometrium. This means that too much estrogen can lead to endometrial carcinoma.
Increases albumin production in liver: during pregnancy, this increased albumin binds more thyroid hormone, increasing the total T4. However, the free thyroid hormone remains the same.
Estrogens also increase coagulation factors in the liver, this can lead to increased clotting.
Estrogen is why women are shorter than men. It causes closure of the growth plates. This is the reason why you should correct early pueberty in girls, to prevent them from being too short.

Mother of All Inducers

2008-11-12T21:09:00.004-05:00

Barbiturates, as a class, are the most prolific inducers known, affecting almost all P450 enzymes. Inducers generally do not create drug-toxicity interactions when an inducer is added, however, on withdrawing an enzyme inducer, the resultant decrease level of enzyme will result in increased levels of drugs metabolized by these enzymes and could result in severe toxicity.

DDx of Positional Headaches

2008-11-12T08:25:00.005-05:00

Two conditions that cause positional headaches are:

1. Colloid Cysts in the third ventricle which block the Foramen of Monro when a person changes position.

2. Post-spinal tap headache. Make sure the patient lies flat after the procedure.

Vomiting in Peds

2008-08-14T14:44:00.001-04:00

Pyloric Stenosis vs Viral Gastroenteritis

PS: voracious appetite
Viral GE: no appetite

Internship

2008-07-05T15:27:00.003-04:00

Hi everyone. Recently, I haven't posted as often because I started my internship last week. I'll pick up the posting in a week or so.

The ABCD's of drugs that slow down the AV node.

2008-07-05T15:24:00.002-04:00

Four drugs can slow down the AV node and thus lead to heart block and probably should not be used in WPW.

A=Adenosine
B=Beta Blocker
C=Calcium Channel Blockers
D=Digoxin

What goes through my head when I get a calcium question...

2008-06-26T20:01:00.000-04:00

#1: Is calcium too high or too low?
#2: What is the phospate level?

The question stem might not give calcium levels so I might have to look for the S/S of hyper or hypocalcemia. Hypercalcemia is classically summarized by the mnemonic "stones, bones, abdominal groans and psychic moans". Hypocalcemia is best remembered by the 2 signs associated with it, Chovstek's sign and Trousseau's sign. The tricky part is that hypocalcemia causes tetany, not hypercalcemia. Most people get this backwards.

The phosphate level tells me who is causing the problem, vitamin D or PTH. The "job" of PTH is to increase free calcium and to decrease phosphate. This leads to a high calcium and a low phosphate. The "job" of vitamin D is to increase both calcium and phosphate, increasing bone mineralization.

So if calcium is high and phosphate is low, PTH did its job. If calcium is low and phosphate is high, PTH is sleeping and should be fired.

If both calcium and phosphate are high, vitamin D did its job. If both are low, vitamin D is slacking.

Next post: what to do with your newfound information on PTH and vitamin D activity.

Answer to the Endocrine Question

2008-06-25T19:04:00.002-04:00

This question really boils down to a calcium question and the choices should be broken down into what causes hypocalcemia and what causes hypercalcemia.

WRONG ANSWERS:
Choice (A) lung cancer was put there because of the distractor in the stem, the possibility of squamous cell lung cancer and the paraneoplastic syndrome associated with hypercalcemia and PTHrp (PTHrp is not measured when you get a PTH level. PTH should be suppressed due to the high calcium levels).

Choice (B) primary hyperparathyroidism is another distractor because the patient has a high PTH level. But when does primary hyperparathyroidism ever cause hypocalcemia? Never!

Choice (D) thyroidectomy done by a sloppy surgeon can sometimes cause hypocalcemia due to the inadvertant removal of the parathyroid glands. This would indeed cause hypocalcemia, but, PTH would NEVER be elevated.

Choice (E) plasma cell infiltration of the bone marrow referred to multiple myeloma, which is in the differential diagnosis of HYPERcalcemia. PTH would be suppressed.

ANSWER:
Choice (C) renal failure is the answer because it is the only choice that can cause hyperphosphatemia, hypocalcemia and elevated PTH. The history of diabetes is subltly included but it is not necessary to answer this question. I used to get confused with renal disease until I boiled it down to, "don't give chronic renal failure patients Coca Cola." The main problem with calcium in renal failure is due to the high phosphate levels that the kidneys can't get rid of. The phosphate and the calcium combine in the blood. This lowers the calcium. The parathyroids go into panic mode and try to raise calcium by destroying the bones (osteitis fibrosa cystica).

What's in a name... Baclofen

2008-06-24T20:37:00.002-04:00

If you want a clue on the MOA of baclofen, add "GA" to the front of the name to make GAbaclofen. Baclofen is a GABA B agonist used for its muscle relaxing properties.

Find the Gold Standard... Endocrine question

2008-06-24T19:05:00.005-04:00

A 65 y/o male is admitted to the hospital for a lower lobe pneumonia. His past medical history includes diabetes mellitus, COPD, and hypertension. He is a chronic smoker, with a 50 pack year smoking history. Upon admission to the hosptital, his lab report shows decreased serum calcium levels, elevated phosphate levels, and and elevated intact serum PTH levels. What is the most likely cause of abnormal lab values?

A. Lung cancer
B. Primary hyperparathyroidism
C. Renal failure
D. Thyroidectomy
E. Plasma cell infiltration in the bone marrow

Please leave you answer in the comments section along with what you think is the "gold standard" of this question. I will post my reponse tomorrow.

Find the Gold Standard!

2008-06-18T23:14:00.004-04:00

A 35-year-old diabetic woman presents to her gynecologist with complaints of burning on urination for the past 2 days. Dipstick test of her urine demonstrates markedly positivity for leukocyte esterase, but no reactivity for nitrite. Urine culture later grows out large numbers of organisms. Which of the following bacteria are most likely to be responsible for this patient's infection?

A. Enterobacter sp.
B. Enterococcus faecalis
C. Escherichia coli
D. Klebsiella pneumoniae
E. Pesudomonas aeruginosa

The gold standard in this question is not the culture, because all five of these bugs will grow on agar. Here the gold standard is the "no reactivity for nitrite." Production of nitrites is typically found in gram negatives when the converted nitrate to nitrite (via reductase). So this question boils down to which one of the bugs is the gram positive? Enterococcus (B) is the answer to the question, but I wanted to bring the trickiness of the name Enterococcus to everyones attention. It sounds too similar to the gram negatives sp. Enterobacter. I have confused these two since I opened my first micro book. Nowadays, I consciously slow down my reading whenever I see the word "entero." Enterotoxin and endotoxin are often confused as well. So be careful!

2 for 1 Deal... Hemolytic Diseases with Gallstones.

2008-06-18T22:51:00.003-04:00

There are two hemolytic diseases with bilirubin stones as complications. One is sickle cell anemia, and the other is hereditary spherocytosis. One quick and dirty way to tell them apart is by looking at the spleen size. Sickle cell patients will have a spleen the size of a walnut buy the age of 2. Hereditary spherocytosis is the only hemolytic anemia with an enlarged spleen.

What's in a Name: HUS and TTP

2008-06-17T19:22:00.004-04:00

Hemolytic uremic syndrome often follows an infection from E. coli O157:H7. HUS should really be called H.U.T.S (hemolysis, uremia, thrombocytopenia syndrome). Questions with syndromes are tricky becuase most people miss them because instead of saying directly hemolysis, uremia, and thrombocytopenia, the stem will usually say that the patient has increased LDH and decreased haptoglobin, elevated BUN and creatinine, and petechiae.

If you add altered mental status and fever to HUTS, you get TTP.

The way that I see the "big picture" and avoid getting lost in the details of a question, I read through the stem pretty quickly, painting a picture of whats going on in the patient. If the AST/ALT is elevated, the liver is likely involved. If there is hemoptysis, the lungs are invovled.

I then do some very basic math in my head... Liver + Lung = could be alpha 1 antitrypsin deficiency in a young, non-drinker with cirrhosis and hemoptysis.

Question Dissection

2008-06-15T23:52:00.006-04:00

Question:

A mailman gets a severe bite wound from a pit bull guarding a junkyard. The wound is cleansed and he receives a booster injection of tetanus toxoid and an injection of penicillin G. Several days later, the wound is inflamed and purulent. The exudate is cultured on blood agar and yields gram-negative rods. Antibiotic sensitivity tests are pending. The most likely agent to be isolated is

A. Actinomyces israelii

B. Leptospira interrogans

C. Clostridium tetani

D. Pasteurella multocida

E. Capnocytophagia canimorsus

Answer: (D) Pasteurella multicida

It is important to know the infections you get from a cat/dog bite, scratch, and urine.

Bite: Pasteurella multicida
Scratch: Bartonella henselae
Urine: Leptospira interrogans

Of the above choices, only two are gram negative rods, Pasteurella and Capnocytophagia. Actinomyces is "actin like a myces" so it is a gram positive filamentous rod. Leptospira is a spirochete. Clostridium is a gram positive rod. The tricky one is (E) Capnocytophagia canimorsus. If you look at the name, Capnocytophagia, you can see the "capno" and the "cytophagia." "Capno" refers to carbon dioxide and "cytophaga" means "cell eater." Capnocytophagia is a fastidious grower which requires a microaerophilic environment to grow so it probably wouldn't grow on the above blood agar.

One of the most my important resources is my Stedman's medical dictionary. I have it on my Blackberry, computer, and Palm. Stedman's is nice because it gives you the Latin and Greek roots of the words. How can you answer a question if you don't know the difference between sclerosis and stenosis? In the question above, knowing that "capno" meant carbon dioxide, gave me enough information to get a similar question right on my USMLE Step 1.

What's in a Mnemonic: encapsulated organisms

2008-06-15T14:27:00.005-04:00

One of the most high yield mnemonics in microbiology is the one for encapulated organisms:

"Some Nasty Killers Have Some Capsule Protection":

Streptococcus pneumoniae
Neisseria meningitidis
Klebsiella pnemoniae
Haemophilus influenzae
Salmonella typhi
Cryptococcus neoformans
Pseudomanas aeruginosa

Most people know this mnemonic. However, many people don't realize how many questions they can answer just by memorizing just one sentence.

The following are uses for the above mnemonic:

If the question presents a patient missing anything needed to kill encapsulated organisms (eg spleen, IgG, C3b, macrophages, etc.), they are at increased risk for infections from the above bugs.
Diseases that are infamously susceptible to encapsulated organisms:

anyone who doesn't have a functional spleen (eg: sickle cell)
Bruton's agammaglobulinemia

If an organism has a capsule, some vaccines are made against the capsule

Pneumococci
Meningococci
H. influenzae type b

Usually, the capsule is a major virulence factor for the above organisms.
If the question mentions a positive Quellung reaction, look for one of the above bugs for an answer.
Big mucoid colonies on blood agar is Klebsiella (from a big mucoid capsule)

How to find the gold standard in each USMLE question.

2008-06-13T11:31:00.014-04:00

A 68 year old male presents with 5 days of fever, non-productive cough, confusion, and a chest x-ray showing non-specific pneumonia. He works in a community hospital with a desk underneath an air-conditioning vent. A sputum culture is taken and it grows a large number of organisms on blood agar. What is the most likely cause of his pneumonia?

The answer to this question could be a number of things, but the one thing I'm certain about, is that the answer is NOT Legionella pneumophilia. True, he has exposure to air-conditioning and presents with the typical symptoms of Legionella pneumonia, but when did Legionella ever grow on normal blood agar? It is a fastidious organism that grows on charcoal yeast extract (CYE) agar. Most of the people I ask know the culture requirements of Legionella, but those same people still answer Legionella for the preceding stem. Why does this happen? And how do you prevent yourself from making the same mistake again?

The way I avoid making this mistake on a multiple choice test is by finding the "gold standard" information in each question. Usually the gold standard information is found in the pathology or microbiology report, followed by blood tests, radiology reports, physical exam, patient history, and finally by risk factors, in that order. A good example of this is found in the treatment of cancer. Would you be willing to give a patient months of chemotherapy based on a just a history of smoking and a cough? How about a single calcified nodule in the lungs? How about a pathology report showing small cell lung carcinoma? I think most of us would rely on the later for our treatment decisions.

The same logic can be applied to answering our original scenario. Would you give this patient the drug of choice for Legionella, a macrolide, based on the history of exposure to air conditioners? If that is how medicine was practiced, I would be on erythromycin right now. The differential diagnosis of diseases in people who were exposed to air conditioners includes just about ALL diseases.

Here is my "gold standard" list from most reliable to least reliable.

Pathology/histology reports
Microbiology cultures/stains
Blood tests including CBC, electrolytes, tumor markers, hormone levels
Radiology reports
Vitals and physical exam
Symptoms
Patient's past medical history
Patient's age
Patients risk factors
Family history

Is it jaundice... or too many carrots?

2008-06-11T21:47:00.006-04:00

TOO MUCH BILIRUBIN BEING PRODUCED ("hemolytic jaundice")

Ineffective hematopoiesis", i.e., normoblasts dying in the bone marrow

Thalassemias (even mild ones like beta-thal minor)

Megaloblastic anemias (folate or B12 deficiencies)

Intravascular hemolysis (many causes)

Extravascular hemolysis

Big hematomas

GI bleeding

LIVER FAILS TO TAKE UP AND/OR CONJUGATE BILIRUBIN ("hepatocellular jaundice")

Newborns (don’t give opiates (except meperidine), sulfonamides)

Hypoperfusion (CHF)

Bad alcoholism

Hepatitis (many causes)

Cirrhosis (many causes)

Glucuronyl transferase (solubilizes bilirubin)

Gilbert’s non-disease [worse w/ fasting)

Crigler-Najjar

LIVER DOESN'T SEND BILIRUBIN TO THE RIGHT PLACE ("cholestatic jaundice" water soluble so urine can be darker)

Problems with the liver cells

Drugs (estrogen, anabolic steroids)

Dubin-Johnson (pigmented) non-disease

These people lack a pump

Rotor (non-pigmented) non-disease.
Problems with the bile ducts in the liver

Biliary cirrhosis
Biliary atresia

Problems with the bile ducts beyond the liver (surgical)

Gallstone in the common duct (the only time a gallstone in the gallbladder will cause jaundice is in Mirizzi Syndrome)Cancer (i.e., biliary, pancreatic, ampullary)
Iatrogenic (i.e., the surgeon nicked the common bile duct)

BTW: the eye sclera should never be yellow if the "jaundice" from carrots.

Gram Positive Cocci MindMap

2008-06-10T23:20:00.001-04:00

2 for 1 Deal... Ramsay Hunt Syndrome and Bullous Myringitis

2008-06-09T00:43:00.002-04:00

The differential of vesicles/bullae in the external ear are Ramsay Hunt Syndrome and bullous myringitis. Ramsay Hunt Syndrome is an extremely painful manifestation of varicella zoster virus and is one of the indications for IV acyclovir. It can also include hyperacusis and loss of taste to the anterior 2/3 of the tongue. Bullous myringitis (image on right) is seen atypical (non-productive cough) pneumonia from mycoplasma.

2 for 1 Deal... Salmonella typhi and Ceftriaxone

2008-06-05T15:20:00.003-04:00

Two unusual things "live" in the gallbladder. One is S. typhi, which is a motile gram negative rod who "swims" upstream from the colon to the gallbladder and lives there chronically (see Typhoid Mary). It also famous for causing rose spots on the abdomen and relative bradycardia.

Ceftriaxone is a lipid soluble third generation cephalosporin which is famous for treating a wide variety of diseases including gram negative and gram positives. Since it is lipid soluble it can cross the blood-brain barrier and is useful for the empiric treatment of meningitis. Like most lipid soluble drugs, it is metabolized by the liver and is excreted in the bile. It reaches very high concentrations in the gall bladder where is causes gallbladder sludge.

2 for 1 Deal... Botulinum and Eaton Lambert Syndrome

2008-06-03T23:17:00.000-04:00

2 diseases inhibit the release of ACh from the presynaptic terminal. The obvious one is the botulinum toxin. The other disease is Eaton Lambert syndrome which is an autoimmune process in which antibodies develop to the voltage-gated calcium channels and impair the release of ACh from the presynaptic terminal. Eaton Lambert syndrome is often a paraneoplastic syndrome associated with small cell lung cancer.

Myasthenia gravis and Eaton Lambert often appear in the same question. The key difference to look for in the question stem is whether or not the weakness gets better or worse throughout the day. Myasthenia gravis gets worse as the day progresses. Eaton Lambert gets better.

2 for 1 Deal... Idiopathic Thrombocytopenic Purpura and Abciximab

2008-06-02T23:55:00.000-04:00

Idiopathic thrombocytopenic purpura and the drug abciximab both target platelet membrane glycoprotein IIb-IIIa. ITP is an immune destruction of platelets. Besides being impossible to pronounce, abciximab is used in patients undergoing percutaneous coronary intervention, and is an antiplatelet agent.

Gluteus maximus, medius, minimus

2008-06-02T22:38:00.001-04:00

It is easy to mix up the actions and innervations of the gluteus maximus, gluteus medius, and gluteus minimus. The easiest way to approach questions on the gluteal muscles is to group the gluteus medius and minimus together. The medius and minimus both abduct the hip or more importantly, they allow our hips to stay level when we stand on one leg (Trendelenburg Test). The gluteus maximus helps us get out of a chair. The trick to these muscles is their innervation. The maximus goes with the inferior gluteal nerve. The medius and minimus are both innervated by the superior gluteal nerve. Be aware of this because it would seem logical that the maximus would go with the superior, but it doesn't!

2 for 1 deal... Achalasia and Hirschsprung's Disease

2008-06-01T01:49:00.000-04:00

Achalasia is the Hirschsprung's of the esophagus. Both are missing the Auerbach's plexus (or myenteric plexus). Both have problems relaxing. Achalasia causes a megaesophagus and Hischsprung's causes a mega colon.

Note that Chagas disease = achalasia + Hirschsprung's. Chagas disease can cause both a megaesophagus and a megacolon.

Opposites: SIADH vs DI drugs

2008-05-31T01:39:00.001-04:00

SIADH Drugs:

Acetaminophen
Barbiturates
Carbamazepine
Chlorpropamide
Clofibrate
Cyclophosphamide
Indomethacin
Isoproterenol
PGE1
Meperidine
Nicotine
Tolbutamide
Vincristine

Diabetes Insipidus Drugs:

Ethanol
Phenytoin
Chlorpromazine
Lithium
Demeclocycline
Glyburide
Amphoterocin B
Colchicine
Vinblastine

Bicycles in my urine!

2008-05-31T01:25:00.001-04:00

There are two important "cycle" drugs that cause problems in the GU system. Picture a bunch of bicycles riding around in the renal tubules and bladder. The first drug is a"cyclo"vir which crystalizes in the renal tubules. The other drug is "cyclo"phosphamide which causes the infamous hemorrhagic cystitis which is prevented with mesna.

My approach to diuretic questions

2008-05-30T12:55:00.001-04:00

DDx of diuretics

Loops
Thiazides
K+ sparing
Acetazolamide

My first rule: all diuretics cause hypokalemia except for 3 drugs (potassium sparing diuretics)

Spironolactone (competitive aldosterone antagonist, also interferes with testosterone synthesis causing incr estradiol in treating hirsutism in PCOS. Spironolactone has been shown to improve mortality in patients with CHF by blocking the toxicity of aldosterone as it hits the heart. (Weird MOA)
Amiloride (inhibits directly, the Na/K pump in the DCT)
Triamterene (same MOA amiloride)

To separate all of the diuretics that cause hypokalemia, look at the [Ca++] to separate loops and thiazides.

Loops lose everything including Ca++, so if the patient is hypokalemic and hypocalcemic, they are probably on a loop (furosemide, torsemide, ethacrynic Acid, bumetanide) be careful of ethacrynic acid, it's name doesn’t look like a loop at all!
Thiazides cause increased Ca++ reabsorption from renal tubules so they cause hypercalcemia, but they are used to treat calcium renal stones because they decrease Ca++ in the tubules, where it is causing the problem.

To separate acetazolamide from loops and thiazides, look at the acid-base status.

Acetazolamide is one of the few things that causes a metabolic acidosis with hypokalemia. Acetazolamide is a carbonic anhydrase inhibitor producing an alkaline diuresis. (you pee bicarb, and with the bicarb, Na follows). Usually, acidosis goes with hyperkalemia. Acetazolamide is also used to decr aqueous humor production and to treat acute mountain sickness.

Be aware that licorice acts like aldosterone, so it can cause hypokalemia.

ACE-I and Digoxin causes hyperkalemia so watch these drugs with spironolactone.

If you get a question w/ Bartter’s Syndrome (mutation of the Na+/K+/2Cl- cotransporter in TAL, just look for the lab values that match a loop diuretic (remember loops LOSE everything). You must rule out diuretic abuse in a patient you suspect has Bartter’s Sydrome.

Highly protein bound drugs

2008-05-28T23:59:00.000-04:00

Warfarin, phenytoin, valproic acid, diazepam

o Generally have low volumes of distribution

o Can be displaced and are usually lipid soluble

PGE1 agonists

2008-05-21T19:18:00.001-04:00

Misoprostol: used for prophylaxis of GI ulcers when on NSAIDS. Think of drinking "miso" soup to help your stomach pain. Look at the "prost" to remind yourself of its MOA, prostaglandin E1 agonist.

Alprostadil (prostaglandin E1): maintains patency of ductus arteriosus (opposite of what indomethacin or any NSAID does). Look at the "prost" to remind yourself of the MOA, PGE1 agonist and look at the "dil" to remind yourself that it DILates the PDA.

DDx Diarrhea in AIDS patients

2008-05-19T22:22:00.000-04:00

Diarrhea in HIV/AIDS

DDx

Viral:

CMV colitis, also causes CMV esophagitis

Bacterial:

Campylobacter, Salmonella, Shigella, Clostridium difficile, Mycobacterium avium complex (MAC), tuberculosis

Protozoal:

Cryptosporidium (no real treatment available)

Entamoeba histolytica (amoebic dysentery, look for liver abscess as well)
Giardia (watery diarrhea, often prolonged, with bloating, gas and malabsorption; upper GI symptoms w/ lower GI symptoms; risk factors: anal sex and drinking "pure" mountain water)
Isospora, microsporidia

HIV-associated malabsorption

What's in a name... Amiodarone

2008-05-16T23:18:00.000-04:00

Amiodarone

Iodine: think iodine in the lungs (pulmonary fibrosis, iodine in the liver (hepatic necrosis), iodine in the eyes (corneal deposits), iodine in the skin (smurf skin, phototoxicity), iodine is also in thyroid hormone (thyroid dysfunction).

What's in a number?

2008-05-16T03:38:00.000-04:00

If you didn't notice, I reformatted the goljan lectures to 1.618 times speed. I will send my biochem on crack usmle lectures the first person who leaves a comment correctly identifying the significance of the ratio 1.618.

Chemotactic Factors

2008-05-16T01:08:00.000-04:00

Chemotactic Factors for Neutrophils

Bacterial Products (i.e. teichoic acid)

Components of the complement system, particularly C5a

Products of the arachidonic acid metabolism, particularly

Leukotriene B4

Chemotactic Factors for Monoctyes

Bacterial Products

C5a components of complement

Fibrinopeptides

Leukotriene B4

Lymphokines

Growth factors (PDGF, TGFB)

Fragments of collagen and/or fibronectin

Chemotactic factors for Eosinophils

Leukotriene B4

Prostaglandin D2

Histamine

Eosinophil chemotactic factor of anaphylaxis

My Antibiotics Lecture

2008-05-15T03:25:00.001-04:00

Nitroprusside

2008-05-14T22:40:00.000-04:00

Nitroprusside has an important indication for the treatment of hypertensive emergencies. However, it is more famous for its side-effect, i.e. cyanide poisoning. How do we associate nitroprusside with cyanide poisoning?

o We already associate Prussian with blue (i.e. “Prussian Blue”)

o Cyanide (cyan is a bluish color)

o So we know that nitroprusside has blue in it from cyanide

o If you use nitroprusside for too long, you can cause cyanide poisoning.

Coombs vs Indirect Coombs

2008-05-13T16:34:00.001-04:00

What's in a name?

2008-05-11T15:40:00.001-04:00

A very famous question on the boards is what clotting factor enoxaprin works on. The answer is in its name; enoXaprin works on factor Xa!

Is the ampicillin rash the new MonoSpot for EBV?

2008-05-10T01:53:00.000-04:00

the sensitivity of the monospot for EBV is 85%. if you give ampicillin to a patient with EBV, >90% will get a maculopapular rash. this means that if a person has infectious mono, they are more likely to break out into a rash after receiving ampicillin than having a positive monospot test.

fyi: up to 80% of patients with CLL also break out into a rash after receiving ampicillin.

Adenosine vs. Theophylline

2008-05-08T16:10:00.000-04:00

These drugs have opposite actions on same receptors: adenosine treats arrhythmias but causes asthma, theophylline causes arrhythmias but treats asthma

Abnormal Cell Counts in various fluids

2008-05-05T10:38:00.000-04:00

Should culture fluids with these abnormal cell counts

CSF>5
Urine>10
Ascites>250 pmn's or >500 wbc's
Joint>2,000 for inflammation or >20,000 for infection

So in other words, your brain should have the least wbc's followed by your pee, belly and joints.

Skin findings in conditions with GI bleeding

2008-05-05T10:35:00.000-04:00

Pigmented macules on lips, palms and soles: Peutz-Jegers
Cafe au lait spots: Neurofibromatosis
Spider angiomata: liver cirrhosis
Acanthosis nigricans: neoplasm
Fragile skin and keloids: Ehlers Danlos
Webbed neck, purpura and skin nodules: Turner's syndrome

Cardiac drugs that induce pulmonary symptoms/disease.

2008-05-05T10:27:00.000-04:00

Amiodarone - pneumonitis and pulmonary fibrosis
Beta blockers - bronchoconstriction (especially with BB's N-Z)
ACE-I - dry cough (take patient off of ACE-I and put on ARB)
Drug induced SLE (hydralazine, INH, procainamide, etc) - pleurisy (anti-histone antibodies)
Aspirin - Sampter's triad (rhinitis, nasal polyps, bronchospasm/asthma; if i see nasal polyps in a question I am immediately looking for aspirin or asthma in the answer)

Why are patients with SIADH normovolemic?

2008-05-05T10:22:00.000-04:00

Increased ADH with H2O intake causes increased ECF. This volume expansion activates the volume receptors in the heart and causes the release of ANP. ANP causes naturesis w/ some kaliuresis and diuresis. The loss of Na keeps enables the body to have a normal volume.

DDx of exophthalmos

2008-05-05T10:20:00.000-04:00

DDx

Graves’ ophthalmopathy (B/L)
Tumor (usually unilateral)
Hand-Schuller-Christian disease (eosinophilic granuloma)

DDx of Pulseless electrical activity (PEA)

2008-05-05T10:17:00.000-04:00

’CHEAPMD’ (mnemonic)

Cardiac Tamponade
Hypoxia, Hypovolemia, Hypothermia, Hyperkalemia
Embolism (massive pulmonary embolism)
Acidosis
Pneumothorax (tension pneumothorax)
Myocardial Infarction
Drug overdose, eg, tricyclic antidepressant, digoxin, beta blocker, calcium channel blocker

Paraneoplastic Syndromes

2008-05-05T10:16:00.001-04:00

Etiology

(++ = strong association; + = reported association)

Endocrine
Cushing's syndrome

Small-cell lung cancer: ++
Non-small-cell lung cancer: +

Gonadotropin excess

Small-cell lung cancer: ++
Non-small-cell lung cancer: +
Gastrointestinal cancers: +
Gestational trophoblastic disease: +
Renal cell cancer: +
Carcinoid: +

Hypercalcemia

Small-cell lung cancer: ++
Non-small-cell lung cancer: +
Breast cancer: +
Multiple myeloma: +
Lymphoma: +
Prostate cancer: +

Hyperthyroidism

Gestational trophoblastic disease: +

Hypoglycemia

Gastrointestinal cancers: +
Hepatocellular cancer: +

SIADH

Small-cell lung cancer: ++
Non-small-cell lung cancer: +

Neuromuscular
Dermatomyositis/polymyositis

Small-cell lung cancer: ++
Non-small-cell lung cancer: +
Breast cancer: +
Gastrointestinal cancers: ++
Ovarian cancer: +
Myeloproliferative disease: +

Lambert-Eaton syndrome

Small-cell lung cancer: ++
Breast cancer: +
Gastrointestinal cancers: +
Ovarian cancer: +

Sensorimotor peripheral neuropathy

Small-cell lung cancer: ++
Non-small-cell lung cancer: +

Stiff man syndrome

Breast cancer: +
Ovarian cancer: +

Subacute cerebellar degeneration

Small-cell lung cancer: ++
Non-small-cell lung cancer: +
Gastrointestinal cancers: +
Lymphoma: +
Ovarian cancer: +

Skin
Acanthosis nigricans

Non-small-cell lung cancer: +
Breast cancer: +
Gastrointestinal cancers: +
Carcinoid: +
Prostate cancer: +
Myeloproliferative disease: +

Dermatomyositis

Small-cell lung cancer: ++
Non-small-cell lung cancer: +
Breast cancer: +
Gastrointestinal cancers: ++
Ovarian cancer: +
Myeloproliferative disease: +

Sweet's syndrome

Non-small-cell lung cancer: +
Breast cancer: +
Gastrointestinal cancers: +
Lymphoma: ++
Renal cell cancer: +
Ovarian cancer: +
Prostate cancer: +
Myeloproliferative disease: ++

Hematologic
Coagulopathy

Breast cancer: +
Lymphoma: +
Renal cell cancer: +
Carcinoid: +
Prostate cancer: +
Myeloproliferative disease: +

Eosinophilia

Lymphoma: ++

Erythrocytosis

Hepatocellular cancer: +
Renal cell cancer: +
Ovarian cancer: +
Adrenocortical tumors: +
Cerebellar hemangioblastomas: +

Pure red cell aplasia

Non-small-cell lung cancer: +
Breast cancer: +
Gastrointestinal cancers: +
Lymphoma: +
Thymoma: ++

Thrombocytosis

Small-cell lung cancer: +
Non-small-cell lung cancer: +
Breast cancer: +
Multiple myeloma: +
Gastrointestinal cancers: +
Hepatocellular cancer: +
Gestational trophoblastic disease: +
Lymphoma: +
Renal cell cancer: +
Carcinoid: +
Thymoma: +
Ovarian cancer: +
Prostate cancer: +
Myeloproliferative disease: +
Adrenocortical tumors: +
Cerebellar hemangioblastomas: +

Fever

Small-cell lung cancer: +
Non-small-cell lung cancer: +
Breast cancer: +
Multiple myeloma: +
Gastrointestinal cancers: +
Hepatocellular cancer: +
Gestational trophoblastic disease: +
Lymphoma: +
Renal cell cancer: +
Carcinoid: +
Thymoma: +
Ovarian cancer: +
Prostate cancer: +
Myeloproliferative disease: +
Adrenocortical tumors: +
Cerebellar hemangioblastomas: +

Amyloidosis

Multiple myeloma: +
Lymphoma: +
Renal cell cancer: +

Pearl of the Day: DDx of Relative Bradycardia

2008-05-03T17:06:00.000-04:00

Salmonella typhi, leptospirosis, brucelliosis, facticious, beta blocker

Cool infectious disease site!

2008-05-03T17:02:00.001-04:00

Check out Persiflagers Annotated Compendium of Infectious Disease (PACID). This site is filled with great practical advice and excellent pearls for infectious diseases.

Best Programs for your Blackberry, Palm, Pocket PC

2008-05-03T16:51:00.001-04:00

Pepid Clinical Rotation Companion - best program by far. Has an excellent disease database, drug list and medical calculator. Major drawback is it's price, but you get 1 free month trial. (pepid.com Blackberry, Palm, Pocket PC)
iSilo - allows you to carry Harrisons, Washington Manual, Robbins, Netter's, etc in your palm. There is now a beta release of iSilo for the blackberry. Best feature is the ability search entire document. (isilo.com Blackberry, Palm, Pocket PC)
Epocrates (free version) - The minimum any student should have on their palm for drug references. (epocrates.com Blackberry, Palm, Pocket PC)

Female pathology by age

2008-05-01T19:27:00.001-04:00

Where in the brain?

2008-05-01T19:20:00.001-04:00

Bile Acid Secretion

2008-05-01T19:16:00.001-04:00

Acid secretion in stomach

2008-05-01T19:15:00.001-04:00

Sinusitis and Wegener's Granulomatosis

2008-05-01T19:13:00.001-04:00

Granulomatous diseases of the lung

2008-05-01T19:10:00.000-04:00

Sulfonamides

2008-05-01T18:45:00.000-04:00

Quinolones

2008-05-01T18:44:00.001-04:00

Drugs to use in pregnancy

2008-05-01T18:25:00.000-04:00

Neonatal Infections

2008-05-01T18:22:00.001-04:00

High Yield Zoonotic Infections

2008-05-01T18:20:00.000-04:00

Bacteria stains

2008-05-01T17:49:00.001-04:00

Gram negative rods

2008-05-01T17:48:00.001-04:00

Bacteria flow sheet

2008-05-01T17:47:00.000-04:00

Hypersensitivity Reactions

2008-05-01T17:36:00.000-04:00

Primary Bone tumors by age

2008-05-01T16:29:00.001-04:00

1st or 2nd decade: Ewing's Sarcoma

Location: diaphysis of long bones

t(11;22)(q24;q12)
characteristic "onion skin" periosteal reaction on plain XR.

10-25 yrs: Oseosarcoma/Osteogenic Sarcoma

"fir-tree" or "sun-burst" appearance on X-ray examination
Codman's triangle - periosteum lifted into a triangle as the tumour emerges through the cortex

the American Cancer Society states: "Probably in no other cancer is it as important to perform this procedure properly. An improperly performed biopsy may make it difficult to save the affected limb from amputation"
Location: metaphysis

"far from the elbow, close to the knee"

proximal humerous, the distal radius, the distal femur and the tibia

>30 yrs: Chondrosarcoma
>50 yrs: Multiple Myeloma

How to keep the locations of Ewing's vs Osteosarcoma straight...
"E" is closer to "D" (Ewing's-Diaphysis)
"O" is closer to "M" (Osteosarcoma-Metaphysis)

Familial syndromes causing sarcomas include:

neurofibromatosis
familial retinoblastoma
Li-Fraumeni syndrome
Beckwith-Wiedemann syndrome
basal cell nevus
Gardner syndrome

Vasculitides

2008-05-01T16:17:00.000-04:00

Monoclonal Antibodies... what's up with the name abciximab?

2008-05-01T16:05:00.000-04:00

The following guidelines have been developed for monoclonal antibodies:

1. The suffix -mab is used for monoclonal antibodies and fragments.

2. Identification of the animal source of the product is an important safety factor based on the number of products that may cause source-specific antibodies to develop in patients.

The following letters were approved as product source identifiers:

u = human
o = mouse
a = rat
zu = humanized
e = hamster
i = primate
xi = chimera
axo = rat/mouse
xizu = combination of humanized and chimeric chains

These identifiers are used as infixes preceding the -mab suffix stem, eg:

-umab (human)
-omab (mouse)
-ximab (chimera)
-zumab (humanized)

Subclasses
The general disease state subclass must be incorporated into the name by use of a code syllable. The following disease state subclasses were approved based on products currently before the Council. Additional subclasses will be added as necessary.

Disease or Target Class:

Viral	-vir-
Bacterial	-bac-
Immune	-lim-
Infectious Lesions	-les-
Cardiovascular	-cir-
Antifungal	-fung-
Neurologic	-ner-
Interleukins	-kin-
Musculoskeletal	-mul-
Bone	-os-
Toxin as target	-toxa-

Tumors

Adalimumab

infliximab

colon	-col-
melanoma	-mel-
mammary	-mar-
testis	-got-
ovary	-gov-
prostate	-pr(o)-
miscellaneous	-tum-

In order to create a unique name, a distinct, compatible syllable should be selected as the starting prefix.
Sequence of stems: The order for combining the key elements is as follows: Infix representing the target disease state, the source of the product, and the monoclonal root -mab used as a suffix (eg, biciromab, satumomab, nebacumab, sevirumab, tuvirumab). When combining a target or disease infix stem with the source stem for chimeric monoclonal antibody, the last consonant of the target/disease syllable is dropped, eg:

TARGET	SOURCE	-MAB STEM	USAN
-cir-	-xi	-mab	abciximab
-lim-	-zu	-mab	daclizumab