Dr. Kirtly Parker Jones details the differences we know, the ones we’re looking into, and how these differences are changing the way we heal patients.">

Aug 19, 2016 — Men and women aren’t the same when it comes to physiology, but the male body has been the default in medical research. Today, doctors and researchers are identifying the differences between men and women and how best to treat each individual more effectively. Dr. Kirtly Parker Jones details the differences we know, the ones we’re looking into, and how these differences are changing the way we heal patients.


Dr. Jones: Why can't a woman be more like a man? In the musical "My Fair Lady," Professor Higgins for singing his frustrations in his research project to turn Eliza into a proper lady. But in healthcare the, difference is important. This is Dr. Kirtly Jones from Obstetrics and Gynecology at University of Utah Health Care and this is The Scope.

Announcer: Covering all aspects of women's health. This is "The Seven Domains of Women's Health" with Dr. Kirtly Jones on The Scope

Dr. Jones: Men and women aren't the same. However, in the history of research into health outcomes in medicine, men's biology was the default mode. Except in Obstetrics and gynecology, of course. Researchers were wary of including women in the studies because they knew that there could be variations in how the body worked and how drugs were metabolized during the menstrual cycle. And men, of course, were the same every day, which was not quite true.

Also, women might become pregnant and for untested drugs undergoing research into dosing and side effects, that would be a problem until drug safety was established. So we counted on men to go into the risky drug development battlegrounds, but not anymore. Gender health medicine has become a significant focus at the National Institutes of Health. Research funding requires that a woman be included where appropriate. For instance, not necessary on prostate research but very important in diabetes research. Okay. Well, what are some of the differences?

Body size. Of course, we know that men are often bigger than women, but not always. If body size alone were a bigger factor, we should be dosing drugs by body mass index, or body surface area or just weight. But body size does predict lung size, heart size, artery size and kidney size and the size of the organs may predict how it metabolizes drugs or how it's affected by disease. For instance, a woman's heart vessels are smaller and they might clog up a little more easily and more quietly. Women are less likely to have a massive heart attack and more likely to quietly have heart damage leading to heart failure.

What about body composition? Women carry more fat than men, usually. This may affect how some drugs are stored. Some drugs are distributed in water and some are bound by fat. This can be somewhat important in anesthetic agents, which are fat soluble and might be taken up by fat in women leading to a lower effect per weight in women.

Anatomic shape. Well, we know girls are curvy, but some girls are more curvy than others. Most women have a different hip configuration than men. They have wider hips and that is hip bones, not just fat on the hips. This means that the angle from the hip to the knee is bigger and men's legs are straighter from the knee to the hip. Now, this is important in the rate of knee injuries in female athletes, which is greater than men. And a knee replacement in women doesn't have to be smaller, it has to have a different angle. This is important for your orthopedic surgeon to know.

Absorption. We absorb pills through our stomach in our intestines. Women have slightly less stomach acid and slightly lower gut transit time, which can make some drugs stay around longer to be absorbed more. Of course, there are some men who have lower stomach acid and lower transit times as well.

Metabolism. Women make more of certain kinds of metabolic enzymes in the liver, particularly women on oral hormonal contraception or women who are pregnant. This is particularly important in certain anti-seizure drugs, which may be less effective in women and doses may need to be changed. On the other hand, women have smaller kidneys and less kidney function as they age. So drugs metabolized by the kidneys can hang around much longer in older women.

Another important difference is in narcotics, for which women have a greater effect at lower doses. The same thing with alcohol, women have a greater effect at lower doses. The same is true for some prescription sleeping pills, for which the FTAs implemented labeling to make sure that doctors and patients know that women should be prescribed lower doses.

Now there is the "we don't know why" core category, one of my favorite categories. In this category, we don't really know why there is a difference. We don't know why women have less serotonin than men in their brains. So anti-depressants and anti-anxiety drugs like selective serotonin reuptake inhibitors, SSRIs, have a greater effect, are more effective in depressed women than in depressed men.

All these differences can lead to different side effects in women compared to men. Women have more side effects in drug studies than men. They have more nausea as a side effect. So what should we do about this as clinicians and as patients? First, we should be wary of assuming that all men are alike and all women are alike. We've already been in trouble to say all people are the same, they're all like men. But not all women are the same and not all men are the same. The differences between men and women are evident when we look at large groups of each sex, but individuals may be larger, smaller more or less fat, have different metabolisms than average for their sex.

If our medicine isn't working in the way we hoped, we should take a look at the individual and ask if different dosing or a different drug should be better. If you're having a side effect from a drug, you should let your clinician know. If you're being prescribed a drug or a course of the action like physiotherapy or joint replacement, you should ask your clinician if there are differences between men and women and how should their recommendations be modified.

I read a research study from Japan where there words like "obese" or "fat" or "overweight" were flashed in front of the eyes of men and women in functional FMRI. In men, the brain activity went right to the language center of the brain. "What was that word?" In women, the brain activity went all over to the language center, to the emotion center, to the judgment center. I hope they didn't spend too much money on that study because every woman and man I know could have told them that women are different than men.

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