Errors in First Aid for the USMLE (2007): Musculoskeletal System

February 19, 2007

As always, this comes from an email sent to the First Aid team. Please add any errors or suggestions in the comments section.

Musculoskeletal (all references from Merck Manual and Robbins Basic Pathology)

  1. P.326, Smooth muscle contraction
    1. This diagram shows Myosin light-chain phosphatase (MLCP) acting before contraction. Every other reference I have found details SMC contraction in the following steps
      1. Calcium binds calmodulin
      2. Calcium-calmodulin activates Myosin light chain kinase (MLCK)
      3. MLCK phosphorylates myosin, allowing a crossbridge to form
      4. Contraction follows
      5. MLCP dephosphorylates myosin, allowing for relaxation.
    2. I think this diagram should be changed in the following way:
      1. “Cross-bridge formation with contraction
      2. After the action of MLCP, “contraction” should be changed to ” relaxation.”
  2. P.327, Rheumatoid arthritis
    1. In RA, the DIP is completely spared. A small point, but the image of the Swan-neck deformity should be pointing to the involved joint (hyper-extended PIP) and not the DIP (normal).
  3. P.327, Osteopetrosis
    1. In addition to be called “marble bone disease,” this condition is frequently referred to as “Albers-Schonberg” disease. I think this should be mentioned.
    2. Osteopetrosis also presents with hepatosplenomegaly (secondary hematopoiesis due to loss of bone marrow) and cranial nerve palsies. I think both of these should be mentioned.
  4. P.327, Osteitis fibrosa cystica
    1. This disease is also often referred to as “von Recklinghausen’s disease of bone.”
    2. In the same way that alkaline phosphatase is raised in states of high osteoblastic activity, Tartrate-Resistant Acid Phosphatase (TRAP) levels are raised in states of high osteoclastic activity. I think it is worth mentioning both of these correlates in this section.
  5. P.328, Polyostotic fibrous dysplasia
    1. This disease is often referred to as McCune-Albright. I think the text should be changed to “(McCune-) Albright Syndrome”
  6. P.329, Gout
    1. I think it would be helpful to include “glucose-6-phosphatase deficiency (von Gierke’s)“.
  7. P.330, Scleroderma
    1. After the first bullet point, I think it should say, “Associated with anti-Scl-70 antibody against topoisomerase“.
  8. P.331, Skin disorders
    1. Atopic dermatitis has pruritic eruptions within skin flexures, not on flexor surfaces i.e. you would expect to see them within the elbow crease and around the neck instead of on the surface of the bicep and forearm.
    2. Seborrheic keratosis should include the common vignette descriptions of “ stuck-on appearance” and “greasy.”
  9. P.332, Primary bone disorders
    1. A constant feature of osteoid osteoma (in contrast to osteoblastoma and osteoma) is complaint of pain at the site of the lesion. I think that this should be briefly mentioned: “pt. complains of pain”
    2. A feature of Giant Cell tumor of bone is the complaint of arthritis in a young person (20-40 yoa). I think this should be briefly mentioned: “young pt. complains of ‘arthritis'”.
    3. Osteosarcoma has a bimodal peak in incidence, once in 10-20 year olds associated with Retinoblastoma, and once in the elderly following Paget’s disease of bone. Without this distinction, it makes no sense so list Paget’s disease here because this rarely (if ever) occurs in patients younger than 40. I think this should be changed to:
      1. “Most common primary malignant tumor of bone. Peak incidence in men 10-20 years old (associated with familial retinoblastoma). Smaller second peak in elderly (associated with Paget’s disease of bone, bone infarcts, radiation). Commonly found….”
    4. A feature of Ewing Sarcoma is the complaint of pain and warmth over the site of the lesion. I think this should be briefly mentioned.
  10. P.333, Other ANCA-associated vasculitides
    1. In the same way that the “Lesions are of different ages” in PAN, I think it is worth mentioning that the lesions are all of the same age in microscopic polyangiitis.
  11. P.335, NSAIDS
    1. I do not understand why there is no mention of Aspirin in this section.
  12. P.337, Immunosuppresive agents: sites of action
    1. I do not understand why Tacrolimus (FK506) and Cyclosporine (CSA) are shown as having completely non-overlapping sites of action since they inhibit the exact same pathway at the exact same step (one by binding cyclophilin, the other by binding FKBP).

Return to First Aid Errors page.

Errors in First Aid for the USMLE (2007): Endocrine System

February 19, 2007

As always, this comes from an email sent to the First Aid team. If you find any problems here or things that I’ve missed, please note them in the comments.

Endocrine (all references from Merck Manual, Robbins Basic Pathology)

  1. P.267, Cushing’s Syndrome
    1. The left sidebar states that ACTH-producing tumors can be identified after a high dose of dexamethasone as having “[down arrow] cortisol.” This is not the case for ACTH-producing Small Cell Lung Cancers which do not respond to feedback inhibition of cortisol or its analogues. Instead, these tumors have the same profile in the Dex test as Cortisone-producing tumors described in the sidebar. The sidebar should be changed:
      1. Healthy — [down arrow] cortisol after low dose
      2. ACTH-producing Pituitary tumor — [up arrow] after low dose; [down arrow] after high dose
      3. Cortisone-producing tumor — [up arrow] after low and high doses, unilateral adrenal atrophy (or hyperplasia)
      4. Ectopic ACTH-producing tumor — [up arrow] after low and high doses, bilateral adrenal hyperplasia
      5. Iatrogenic Cortisol administration — [up arrow] after low and high doses, bilateral adrenal atrophy
  2. P.269, Subacute thryoiditis (de Quervian’s)
    1. No mention made that this condition involves granulomatous inflammation of the thyroid, a major characteristic.
  3. P.269, Thyroid Cancer
    1. I think this section should be retitled “Thyroid Tumor” and the following bullet point added first to highlight that the majority of nodes are not malignant:
      1. 90% Benign, adenoma – “hot” on scintigram, Hurthle cells

Return to First Aid Errors page.

Laugh of the Day

February 17, 2007

First Laugh of the Day goes to Ambulance Driver:

I’m going to start my own worker exchange program. I’ve got six malingering, whining, healthcare system abusing, hypochondriac, chemically dependent, Professional Victims of Life that I’ll willingly trade for three hardworking illegal Mexicans who want a shot at the American dream. They can have the jobs that these hunnert percent, by-God Murkins can’t seem to find or hold.

Second Laugh of the Day goes to Indexed:


Renal, Endocrine and Musculoskeletal First Aid sections go up Sunday night.

Sentence of the Day

February 16, 2007

mark-twain.jpgEvery morning I work through a crossword puzzle. Typically, it will reference a few things I know and the rest I ask Google. I bookmark these things and (at night, as a reward) read through them. I hope this becomes a life-long habit. Without further ado…

The Awful German Language, by Mark Twain

This explains why, whenever a person says sie to me, I generally try to kill him, if a stranger.

I heard a Californian student in Heidelberg say, in one of his calmest moods, that he would rather decline two drinks than one German adjective.

O, horror, the Lightning has struck the Fish-basket; he sets him on Fire; see the Flame, how she licks the doomed Utensil with her red and angry Tongue.

You can begin with Schlag-ader, which means artery, and you can hang on the whole dictionary, word by word, clear through the alphabet to Schlag-wasser, which means bilge-water — and including Schlag-mutter, which means mother-in-law.

“In the daybeforeyesterdayshortlyaftereleveno’clock Night, the inthistownstandingtavern called `The Wagoner’ was downburnt.

There were so many other great lines that I had to leave for you. I couldn’t bring myself to rob you of the context.


ich habe gehabt haben worden gewesen sein, as Goethe says in his Paradise Lost — ich — ich — that is to say — ich — but let us change cars.

Dear Self

February 15, 2007

Dear Past Self,

I’ve traveled back in time to give you some advice because right now, I’m a little pissed off. You probably don’t care (which is why you’re indulging in this “rut,” you pussy) but because you’re not going to be around to deal with the consequences, I felt the need to bring them into sharper relief:

You’re fucking up. You’re fucking it all up.

Every day you waste feeling sorry for yourself because you don’t feel “excited” or “energized by the material” is another step you’re falling behind the goals that way-past self set. Now, I think those were good goals and, frankly, I like way-past self way more than you, past self.

If you don’t stop, I’m going to kick us in the balls.

Way-way-past self spent so much time working so that we could even have this opportunity. Way-past-self understood and respected that sacrifice and carried on the tradition and I’m just waiting for you to pass me the torch so I can take us even further. So pass me the torch.

Or just sit there collecting ash on your lap, you lazy shit.

I don’t want to do anything drastic. The last time a future-self had to take the place of a past-self prematurely was in college to end the great marijuana period and to get us in shape. Not only do we not remember anything that happened while pot-self was around but that move (while necessary) came too late to get us into medical school in the US. Do you think I’m going to wait around much longer for you to get your act together before I erase you from our consciousness?

If you hadn’t read Enoch Arden yesterday, I would have already done it.

How to Prepare for the USMLE: Desperation

February 14, 2007

I’m in a rut. For the past five days, I’ve just been going through the motions, not really getting excited by the material or finding any joy in it. Pulmonary was boring, Renal is annoying with all of its ridiculous buzzwords and “subepithelial humps of bullshit” on electron microscopy that I can’t imagine I will ever see in my life, and this has lead me into the slow agonizing march that is endocrinology and reproduction.

I haven’t finished any of the sections. I spend a day on the embryo/anatomy/physiology, a day on the path, and a day on the pharm (if it needs it). Where cardio had me excited, doing questions in WebPath, Robbins Review of Pathology, and in the Usmle World Qbank, I’ve just limped through each day for the better part of this week.

And this is just feeding on itself. Doing well makes you want to continue doing well, and the converse is true. As it stands I look back on all the subjects that I’ve read but haven’t really “finished” and I’m thinking too much about being behind to concentrate on not falling further behind. At this point, I think the only way out is to completely skip the current section and use these days to tie up the loose ends in other subjects.

Maybe I’d rather be completely behind in one subject than a quarter behind in four subjects. Who knows. I’m just writing this here out of desperation. I need this rut to be over before it swallows more than it already has, and I thought writing it down would get it off of me.

Hope it works.

Return to USMLE Step 1 page.

Errors in First Aid for the USMLE (2007): Pulmonary System

February 13, 2007

As always, this comes from an email sent to the First Aid Team.


  1. P.428, Oxygen-hemoglobin dissociation curve
    1. High altitude decreases P02 and decreases Hb saturation. This results in a decrease (or down-shift) in the dissociation curve, not a right shift as described.
  2. P.428, Pulmonary circulation
    1. While exercise does decrease the perfusion limitation, it never reaches the point of diffusion limitation i.e., the SaO2 on an athlete will almost never be lower than it is at rest.
  3. P.431, Obstructive lung disease (COPD)
    1. “[up arrow] FVC” is incorrect. RV increases, FVC is decreased or normal, FEV is decreased, TLC is increased.
    2. Emphysema and Asthma are both listed as having decreased I/E ratios. I assume this means Inspiration/Expiration ratio. This seems impossible as a ratio other than 1 would lead to progressive deflation and collapse of the lungs or the opposite expansion. What this should instead indicate is that in both cases, the breathing is shallow. In any steady state of respiration (including shallow breathing), I/E = 1 and the tidal volume (Vt) is lowered.
  4. P.431, Restrictive lung disease
    1. “([down arrow] VC and TLC)” should say “([down arrow] FVC and TLC)”
  5. P.431, Neonatal respiratory distress syndrome
    1. The opening description describes “lecithin” as the important surfactant. The surfactant is then described as “dipalmitoyl phosphatidylcholine .” I think everyone might benefit if this was changed to:
      1. Surfactant–dipalmitoyl phosphatidylcholine (DPPC, lecithin)
  6. P.432, Obstructive vs restrictive lung disease
    1. The FEV1/FVC ratios are listed for Normal and Obstructive, but not Restrictive even though “>80%” was listed on the previous page. For consistency, I think it should be included here.
    2. The curve for “Normal” is not drawn correctly, listing a ratio of 80% but showing a ratio of 60%.

Return to First Aid Errors page.

Homophobic Idiots and the Snickers Ad

February 11, 2007

Offensive” is a word abused by morons. The latest example is the brouhaha over the Snickers advertisement in the Super Bowl. A synopsis from the Americablog.

A bit of background. The ad in question showed a mechanic eating a Snickers bar. Hi co-mechanic is so desirous of the Snickers that he starts eating it from the other end of the same bar that’s already in the other guy’s mouth. The two butch guys eat their way down the bar, like the dogs eating the same string of pasta in the Disney movie – until they’re accidentally kissing. The guys, naturally, recoil in disgust – then, oddly, start ripping out their chest hair with their hands.

The conclusion that Americablog reaches (as do too many others to list) is that the add is anti-gay, hateful, and supports homophobia.  This is of course followed with protests, angry letters, and blog posts calling for the withdrawal of this clearly offensive add.   Here’s my interpretation:

Two mechanics accidently touch lips because Snickers is so delicious. Each, being a homophobic idiot (HI), worries that the other HI thinks that he is a homosexual. So terrified with this thought (being a HI), they each decide to prove how not gay they are by either:

  1. Hitting each other with wrenches
  2. Drinking motor oil and antifreeze
  3. Ripping out clumps of their chest hair while screaming

Commercial ends and we all laugh at the HIs.

Unless you are a homophobic idiot or a Moron Not Otherwise Specified, I don’t see how you were offended. Unfotunately, it’s easier to placate morons than educate them and Snickers pulled the advertisement.

MNOS or HI? You Decide.

From Worth Repeating

1) It’s OK to beat the crap out of gay guys;
2) If you do something gay-ish, consider countering said act with self-mutilation or a hate crime;
3) Using gays as the butt of jokes is funny — and profitable!

From the Lost Remote:

The backlash was entirely predictable, and Snickers and its ad agency deserves it for being so detached from today’s reality.

He’s right, but it’s by accident. Had they test-marketed it with “real” people I’m sure they would have known this real stupid response was coming.

Fairy Tales

February 8, 2007

I hope this writer over at “The Gentleman’s C” knows what he has here.  A book of these would sell like so many hot cross buns.

The Angry Kid went to a “Princess Party” this past weekend. I overdosed on cheap tulle and the color pink and, to my horror, she now speaks of nothing but her own “Princess Party,” which she believes I am required to provide. Saturday night, at bedtime, the Angry Kid asked for a story. This is what she got.

A  little later in the greatest fairy tale ever

Snow White sighed. “You idiot,” she declared. “There’s no such thing as magic, and wishing for things won’t make them come true. Evil, stupid Queen, get away from here and don’t come back!” With these words, Snow White raised the hammer up high, and the Queen thought Snow White was going to hit her with it. She dropped her basket of nasty apples and ran into the woods, afraid for her life. Unfortunately, she didn’t watch where she was going, and she ran right off a cliff and died.

Scalpel’s Objective Pain Scale

February 8, 2007

This is a good post.

I think the clinician’s assessment of the patient’s pain is more useful than the patient’s assessment of their own pain, as far as triage is concerned. The currently used pain scale is only helpful in assessing response to treatment (the trend). Mine is more realistic:

Scalpel’s Pain Assessment Scale

From my small experience in a hospital, I left with the strong impression that personal pain ratings are more often about what the patient wants than the level of pain the patient is experiencing.  Everyone on my floor new the magic number: 7.  If you’re a 7/10, you get morphine.