Why Organic Chemistry should always be taken (and passed) by pre-meds — take II

An old friend’s mother died of a ruptured intracranial aneurysm and he asked me what his risk was.  So I looked up my old notes on the medical literature that I took when I was in practice (copied below).  They show once again why someone who can’t pass organic chemistry doesn’t belong in medicine.  They are far too out of date to be of clinical use, and hopefully more work has been done since I retired in 2000.

But look at the notes.  All are in reputable journals and have been refereed.  But they conflict.  You have to evaluate this data to give decent advice, just as you have to weigh conflicting steric effects, electronegativity, bond strength, electrostatic effects in solving an organic chemistry problem.  Memorization of the various effects is necessary, but you have to keep them in your head and weigh them.   A perfect memory alone just won’t do.

Here are my notes, followed by the first post on this point (which was almost 10 years ago). You don’t have to go to medical school to see how conflicting they are.

      [ New England J. Med. vol. 341 pp. 1344 – 1350 ’99 ] 626 first degree relatives of 160 patients with subarachnoid hemorrhage were screened for aneurysm by MRI angiography.  Aneurysms were found in 25/626 (not much higher than the literature would imply in any of us — they use the figure of 2.3%) — total number of aneurysms were 33.  18/25 had surgery and 11/18 had a decrease in function (disabling in 1).    They estimate the increase in life expectancy due to the surgery at 2.5 years.   They don’t think the morbidity of surgery is worth it.  The study is from the Netherlands.
      These results can’t be extrapolated to cases were there is more than one member affected by aneurysm (they may have a higher yield of aneurysms, and the risk of rupture may be different).   The screening led to 5 angiographies in patients who didn’t turn out to have an aneurysm — thus exposing a normal person to risk.
      [ Brit. Med. J. vol. 320 pp. 141 – 145 ’00 ] A study of 6175 patients with aneurysmal subarachnoid hemorrhage and 14781 first degree relatives (of whom 11640 were children followed for 108933 patient years showed 19 subarachnoid hemorrhages during followup.   This is an increased risk 3 times that of the general population — however, this translates to an absolute risk of under 1/500 per year.
      [ J. Neurosurg. vol. 66 pp 522 – 528 ’87 ]  A review of the literature on familial aneurysms shows that familial aneurysms tend to rupture at a smaller size and when the patient is younger.   There is a similar incidence of multiple aneurysms and predominance of females over males with multiple aneurysms in the familial cases.  Anterior communicating artery aneurysms are slightly less frequent.  In sibling pairs, the aneurysms occur at the same or at mirror sites and rupture within the same decade twice as frequently as randomly selected nonfamilial aneurysm patient pairs.
      [ Stroke vol. 27 pp. 630 – 632 ’96 ] Familial subarachnoid hemorrhage is said to account for 6 – 9% of all such cases.  The outcome is said to be worse in familial than sporadic subarachnoid hemorrhage.
      [ Stroke vol. 25 pp. 2028 – 2037 ’94 ]  Since the initial report in ’54, there have been 238 families with 560 affected members reported in the literature through ’93. Only 3% of these families had 5 or more affected.   Siblings of an affected male proband are more likely to be affected than siblings of an affected female.  After review of 73 families, the authors conclude that no single pattern of inheritance can account for all families (unsurprise ! ).
        [ Neurosurg. vol. 12 pp. 214 – 216 ’83 ] A family with 4 members with intracranial aneurysms is reported.  Two of these were in an unusual location, the distal anterior cerebral artery.
        The 5th case report of identical twins with multiple aneurysms is given [ Acta. Neurochir. vol. 95 pp 121 – 125 ’88 ]
        [ Neurosurg. vol. 20 pp 226 – 239 ’87 ]  A prospective study of 579 consecutive patients with subarachnoid hemorrhage was done.  1/250 siblings had an aneurysm, but an aneurysm occurred in another family member in 1/14.
      [ Stroke vol. 22 pp. 1426 – 1430 ’91 ]  3 families (among 175 patients with spontaneous dissections of the cervical arteries seen at the Mayo Clinic between 1970 and 1989) were found with intracranial aneurysms.  No patient had both conditions.  Both Ehlers Danlos type IV (ED – IV ) and Marfan’s syndrome can have aneurysm and cervical artery dissection as components.
       [ Stroke vol. 25 pp. 2028 – 2037 ’94 ]  Intracranial aneurysms have been associated with the following hereditary disorders.  However, only polycystic kidney disease, Ehlers Danlos, Marfan’s neurofibromatosis and pseudoxanthoma elasticum are at increased risk of aneurysm.  The others may be fortuitous.  Among the others a alpha-glucosidase deficiency, alpha-antitrypsin deficiency, alkaptonuria, Fabry’s disease, hereditary hemorrhagic telangiectasia, Noonan’s syndrome, tuberous sclerosis, and multiple endocrine neoplasia type I syndrome.
      [ Brit. Med. J. vol. 311 pp. 288 – 289 ’95 ] A study of the first degree (1290) and second degree (3038) relatives of 163 patients with subarachnoid hemorrhage from the Netherlands showed that 10/1290 first degree and 4/3038 second degree relatives had had a subarachnoid hemorrhage.  This is a 6 fold higher risk for first degree relatives than the population at large (however, fewer than 1% of first degree relatives had had a subarachnoid hemorrhage).   3 other studies (which the authors criticize) hadn’t found this.  [ Stroke vol. 27 pp. 7 – 9 ’96 ] A further study of this group showed that hypertension was 2.3 times as common in first degree relatives, stroke was 1.8 times as common and coronary heart disease was 1.9 times as common in first degree relatives (as compared to second degree relatives).  Thus the increased risk of subarachnoid hemorrhage in first degree relatives may reflect an increase in known risk factors for subarachnoid hemorrhage rather than a ‘new’ defect in the arterial walls.
       [ Arch. Neurol. vol. 52 pp. 202 – 204 ’95 ] A much higher incidence of subarachnoid hemorrhage in first degree relatives of the 149 cases of subarachnoid hemorrhage in Seattle over 2 years is reported.  An astounding 11.4% of cases had a first degree relative with a history of subarachnoid hemorrhage (vs. 6.4% of controls through random digit dialing).    When I take family histories (which I do for every patient I see), I don’t get anything nearly this high (I think, but I’ll have to look).   Another study estimated that the percentage of first degree relatives should be 5.5% [ Stroke vol. 23 pp. 1024 – 1030 ’92 ].
     [ Neurol. vol. 53 pp. 982 – 988 ’99 ] Another study on aneurysm risk of first degree relatives of patients who suffered a subarachnoid hemorrhage from an intracranial aneurysm.  There were 193 index patients and 626 first degree relatives studied 78% of those eligible).    Aneurysms were found in 25/626 — a 4% incidence.  The group with aneurysm didn’t have a high number of atherosclerotic risk factors.    This only twice the 2.3% prevalence of unruptured aneurysms in the general population.    The rate of subarachnoid hemorrhage in first degree of aneurysmal bleeders is 3- 7 fold that of the general population.   Given the only twofold increased prevalence of aneurysm found in this study, this may mean that there may be two types of aneurysms which run in families — the bleeding kind and the nonbleeding kind.
     [ Stroke vol. 27 pp. 1050 – 1054 ’96 ] In a study of 30 patients with ruptured aneurysm from 14 families in which another member had an aneurysm 24/30 were women.
        [ Lancet vol. 349 pp. 380 – 384 ’97 ] A study from Finland screened first degree relatives over the age of 30 of index cases of subarachnoid hemorrhage with magnetic resonance angiography (MRA)  There were 698 available of whome 438 were screened with magnetic resonance angiography.  38/438 had aneurysms (families with polycystic kidney disease, Marfan’s, Ehlers Danlos IV were excluded).
        [ Can. J. Neurol. Sci. vol. 24 pp. 326 – 331 ’97 ] The Saguenay Lac Saint Jean area of Quebec contains  ~ 300,000 people (all inbred).  The incidence of familial aneurysm is very high (related to the total aneurysm burden) and 144/502 individuals with ruptured intracranial aneurysm had another affected family member (first to third degree relative).   However, they think this is due to accidental aggregation as the families are large (average number of siblings is 7 ! ).
        [ Neurol. vol. 51 pp. 1125 – 1130 ’98 ] A study of 125 relatives of patients in 23 families in which 2  more individuals had aneurysmal subarachnoid hemorrhage.  116 had no history of aneurysm themselves and 7/116 had an asymptomatic ruptured aneurysm.  9 had a history of aneurysm and 3/9 had new asymptomatic intracranial aneurysms.   MRA was used to study the 116 and CT angiography was used to study the 9.
Here is the first post on the subject, written almost 10 years ago

Why Organic Chemistry should always be taken (and passed) by pre-meds

Back when I was posting on “The Skeptical Chymist”, the editor (Stuart Cantrill), told me that noises were being made about dropping organic chemistry from the pre-med curriculum and asked me to comment. I didn’t because the idea seemed so ridiculous. There is no possibility of really understanding anything about cellular biology, drug action, molecular biology etc. etc. without a firm grounding in organic chemistry. You simply must have some idea what vitamins, proteins, DNA and RNA and the drugs you’ll be using look like and how they chemically interact — which is what organic chemistry gives you the background for. Not that you can stop there — but all medical schools teach biochemistry — which starts at organic chemistry and takes off from there. Organic certainly helped me follow molecular biology as it exploded starting in the 60s.

Cynics might say that docs don’t synthesize things or crystallize the drugs they use. Knowing what’s going on under the hood is just esthetic filigree. Just tell them what ‘best practice’ is, and let them follow it like robots. Who cares if they know the underlying science. People drive cars without really understanding what a carburator or a manifold does (myself included).

It wasn’t until I got about 400 pages into the magnificent textbook of Organic Chemistry by Clayden, Greeves, Warren and Wothers (only 1100 action packed pages to go !) that the real answer became apparent. The stuff is impossible to memorize. Only assimilating principles and applying them to novel situations will get you through — exactly like the practice of medicine.

Let us suppose you have an eidetic memory, and know the best treatment for every condition. You wouldn’t have to know any science at all, would you?

What’s wrong with this picture? First of all, there isn’t a best treatment known for every condition. Second, every doc will see conditions and problems that simply aren’t in the books. When I first started out, I was amazed at how much of this there was. I asked an excellent internist who’d been in practice for 30 years if he’d seen it all. He thought he saw something completely new each week. Third, conditions occur in combinations, and many patients (and nearly all the elderly) have many more than one problem. The conditions and treatments interact in a highly nonlinear fashion. The treatment for one problem might make another much worse (see below).

Here is a concrete example using a familiar person (Sonia Sotomayor) and a disorder which should be known to all (the new Swine Flu which swept America and the world this spring). Let’s say that you’re that lucky soul with the perfect memory who knows all the best treatments (well those that exist anyway) and as such you’ve been given the responsibility of taking care of her.

It is public knowledge (e.g. Wikipedia) that Justice Sotomayor has had diabetes since age 8, requiring insulin since that time. Pictures show, that like many diabetics, she is overweight — depending on how tall she is I’d guess by 25 – 45 pounds. Influenza is usually a disease of the fall and winter, and the new Swine Flu is now down in South America, but it’s likely to sweep back up here this fall. We know it’s extremely infectious, but so far fortunately rather benign. There is no guarantee that it will stay that way. Suppose that while down in S. A. it mutated and has become more virulent (a possibility that the CDC takes extremely seriously).

What if she gets the new Swine flu next month? At this point there is no ‘best treatment’ known. Diabetics don’t do well with infections — they get more of them, and have more complications when they do. Her diabetes is certainly going to get worse. What if some think the ‘best treatment’ is corticosteroids (which is often used for severe lung infections) — which will really raise hell with her diabetes? Should you give it? Recall that corticosteroid use during the Asian SARS epidemic (another serious lung infection) seemed to hurt rather than help (Journal of Infection, Volume 51, Issue 2, Pages 98-102). There is no data to help you here and you and your patient don’t have the luxury of waiting for it. Don’t forget that her father died at 42 of heart disease. That could be relevant to what you do. Suppose, like many overweight diabetics she has high blood pressure and elevated lipids as well. How will that affect her management?

Your perfect eidetic memory of medicine will not be enough to help you with her management — you are going to have to think, and think hard and apply every principle of medicine you know to a new and unfamiliar situation with very little data to help you.

Sounds like Organic Chemistry doesn’t it? Anyone without the particular type of mind that is able absorb and apply multiple and (often) conflicting principles doesn’t belong in medicine. A hardnosed mathematician I audited a course from a few years ago, said that people would come up to him saying that if they couldn’t pass Calculus, they wouldn’t get into medical school. He felt that if they couldn’t, he didn’t want them in medical school (I’m not sure he told them this — probably he did). The same thing holds in spades for Organic Chemistry.

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