1) Morning sickness --> another pearl from evolutionary medicine.

Nausea and vomiting (n/v) in early pregnancy are so common --> they are regarded as almost physiological.

But could they have an evolutionary benefit?
2) Firstly, its not called morning sickness anymore.

Its n/v of pregnancy aka NVP.


Because it takes place at all times of the day and night.
3) We have a graphical representation of the usual course of NVP here.
4) Why does NVP happen?

First of all, NVP does not seem to be common among other mammals (caveat being that very little research has been done on this).

Yet it occurs in upto 90% of human pregnancies!
5) It is believed that NVP causes an aversion to meat, fish, poultry eggs and other strong tasting vegetables in pregnant women.

These may contain harmful toxins and microbes that can harm the pregnant woman or the fetus!
6) What is the proof?

1. NVP peaks during the period of embryonic organogenesis ie between weeks 6 and 18 of pregnancy.

Look at tweet 3!
7) 2. Women who experience NVP are significantly less likely to miscarry!

In fact, women who vomit experience even lesser rates of spontaneous abortion than women who are just nauseated!
8) 3. Aversion to foods like meat, fish, poultry and eggs is understandable --> these were most likely to contain pathogenic organisms and toxins!

Examples --> Listeria and Salmonella!

9) 4. Traditional societies with plant based diets are almost immune to NVP!

These theories were presented by two evolutionary biologists from Cornell University --> SM Flaxman and PW Sherman in 2000!

10) What are the other theories behind NVP?

1. Genetic conflict theory --> that NVP is a byproduct of maternal-fetal genetic conflict --> it is triggered by increasing beta HCG levels --> but NVP peaks ahead of the beta HCG peak --> it leads, where it should lag!
11) But this relationship is not 100% proved.

It is believed that different beta HCG isoforms +/- receptor sensitivity may alter the risk of developing NVP!


2. It is believed that NVP signals to other males and kin that the woman is pregnant --> it signs low sexual activity and need for help.

But sexual activity may not be dangerous during the 1st trimester --> the time of peak NVP incidence!

3. Some early studies proposed that NVP may be a psychosomatic illness --> it is a manifestation of a pregnant woman's desire to reject her fetus --> they found that women with NVP had a higher rates of unplanned/undesired pregnancies.

14) As you can see, NVP is far from a cut and dried topic!

Theories abound!

But this should not distract from the fact this is a clinical situation which ranges from merely troublesome to life threatening ie hyperemesis gravidarum!
I hope you liked this small window into evolutionary medicine!

Please share/retweet if you do!


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More from @AdiG1993

Aug 26
1) Inspired by @AaronGoodman33

Middle aged male gets tired easily, had a hx of TLOC on sudden standing up, low grade fever × past 1 year

Clinical exam --> gradual darkening of skin and oral mucosa.

What is your diagnosis?

What are your differentials?

What labs +/- imaging would you request?
I am surprised nobody thought of hemochromatosis.

Unexplained fatigue and postural hypotension --> hemochromatic cardiomyopathy

Low grade fever --> hemochromatosis renders you susceptible to infection

Hyperpigmentation --> hemoCHROMATOSIS
Read 7 tweets
Aug 21
1) I am a big fan of evolutionary medicine --> the study of human evolution and how it can be harnessed for the practice of medicine.

I recently went in for a deep dive into an important topic --> HYPERURICEMIA

Here is what I learnt!
2) Uric acid is the endproduct of purine metabolism in humans --> this is an exception among mammals!

Why does this happen?

1. Lack of uricase
2. Avid renal reabsorption of uric acid
3) Why happened to uricase?

This ancient enzyme, present since bacteria, accumulated a number of mutations approx 10-30 million years ago and gradually lost its function in humans, some higher primates and some New World monkeys.

Read 23 tweets
Aug 19
1) I'm no expert but the Dolo 650 controversy is either a meaningless or a malignant one.

PCM is an OTC drug --> it is almost never the only drug in a prescription.

2) PCM doesn't provide any significant analgesia unless you are taking 2-3 gm/day.

Its good for the myalgia and arthralgia of febrile illnesses especially if NSAIDs are contraindicated --> like dengue which has a risk of thrombocytopenia.
3) For everything beyond this, you will need an adequate dose of an NSAID +/- local or systemic glucocorticoid therapy --> even DMARDs if its rheumatological!

Most patients in India don't go to a doctor for mild aches and pains --> they will buy PCM directly!
Read 10 tweets
Aug 19
1) A brief review of paracetamol aka PCM

Synthesized by HN Morse at John Hopkins at 1977 --> a derivative of acetanilide and phenacetin.

It has become a common household drug since the 1980s as phenacetin use dropped --> concerns of analgesic nephropathy.
2) It is best known as acetaminophen aka Tylenol in the Western hemisphere.

PCM provides good antipyresis and analgesia --> but anti inflammatory action is minimal.
3) PCM is basically an NSAID that blocks COX1 and COX2 enzymes --> at the peroxide site (distinct among NSAID).

But inflammation raises local peroxide levels --> counters PCM action.

So PCM is a great antipyretic and analgesic but poor anti inflammatory.
Read 10 tweets
Aug 18
1) I have spent 10 years in the medical profession (2012-2022).

Here is what I have learnt -->

1. Contrary to what a lot of people will tell you, an MBBS degree HAS NOT been emasculated --> it is simply no longer sufficient.


Because of the rapid progress of medicine.
2) Medicine has evolved so much in the past 20 years --> you have to run just to stay in the same place.

You need 10+ years of training just to know the basics with some degree of confidence.

Specialization will only increase.
3) Most people will have to rely on parental support for this decades long pursuit of education.

It has a huge economic cost.
Read 4 tweets
Aug 17
1) If I had to choose one thing that really pisses me off in medicine --> diagnostic laziness.

Interventions aside --> medicine is essentially a mind game.

Its all about the 'little grey cells' as Poirot used to say.

In its purest form, medicine is the hunt for a diagnosis.
2) One shouldn't try to fit a poorly constructed hypothesis into an ill fitting diagnostic cubbyhole --> as Prof Miller Fisher said.

The best physicians are ever ready to reconsider a dx as new information comes to light --> they never tire of the hunt which may take years!
3) Patients are many, resources scarce, opportunities too few and time none --> the hunt will never be easy.

But we will not be disheartened.
Read 4 tweets

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