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

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

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.

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

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

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

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.

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!

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

Check out this flash animation!

Is it Crohn's Disease or Ulcerative Colitis?

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!

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

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

My rule: Estrogen causes growth.

1. Estrogen comes from 3 main areas: ovaries, adrenal cortex, and placenta.
2. 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.
   
3. 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.
   
4. Estrogen stimulates the growth of the endometrium. This means that too much estrogen can lead to endometrial carcinoma.
   
5. 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.
6. Estrogens also increase coagulation factors in the liver, this can lead to increased clotting.
7. 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

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

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

Pyloric Stenosis vs Viral Gastroenteritis

PS: voracious appetite
Viral GE: no appetite

Internship

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.

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...

#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

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).