Age and Gender Differences in Blood Test Results

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Just because your blood test result is in the “normal” column, doesn’t mean your hormone level is healthy!

The truth is that when we are young, fertile and healthy our GH, Testosterone and Estradiol are at their peaks.  As we age they decrease and we become symptomatic because we do not have “optimal” young healthy levels any more. This is nature, as well as the reason these hormones are replaced as we age, to treat the symptoms of hormone deficiency and bring us back to youthful health.

Unfortunately, Labcorp and Quest as well as many other labs have not gotten the message that normal young healthy levels are the range of blood levels that should be listed on every person’s lab report.  Instead, they “guess” that if a woman is over 40, that you are menopausal and that the findings of a very low estradiol, testosterone and GH are “normal” for every woman.  Well it may be an average reading for women over 50, not 40, but what is average is not always healthy. The loss of these three hormones cause women to symptomatic with hot flashes and painful intercourse, loss of muscle mass, onset of obesity and inability to participate in physical activities.  These “natural” changes in our hormones are not healthy, and when we are checking lab we are looking for whether a person is healthy or not, right?  By looking at the normal for these three hormones we only find out that they are average for a woman over 40!

I have to explain this to every woman who comes into my office.  Just because the result is in the “normal” column, doesn’t mean your hormone level is healthy! If you don’t see the logic to this then let me explain the way we test for osteoporosis.  We do a Dexa scan that measures the thickness of your bones.  Then we compare your bones, no matter what age you are, to the bones of a 29 year old female.  Yep, a 29 year old female!  Why? Because that is when our bones are the thickest, and after that they start to thin at 1-2% per year.  If they compared old bones to the bones of other old women then no one would have an abnormal bone thickness!

Medicine has decided that it is ok to compare our bones to young healthy women, but they still believe that we should compare our declining hormones to other mature women who all have low hormones.  I don’t see the point in testing hormones at all if that is the way it is interpreted. That is why I list the young healthy normal for every hormone to compare my patients blood levels of Estradiol, Testosterone and Growth Hormone.

In addition to age-skewing of the “optimal or normal levels” of hormones, there are gender differences in the optimal levels for some hormones. Your doctor needs to know these differences and what they mean to your overall health as you age.

An example we would give is the TSH results that are reported on lab sheets are based on male normal ranges. For example, a normal TSH for women not on any thyroid medications should be between .4-2.5, while the normal for men is .4-4.5.  If you are higher than 2.5 and are a woman, you should be treated with thyroid hormone replacement, but you will be told you are normal because you fall in the normal range for men.

Lets look at how this impacts your treatment considerations. If you are female being judged by “male normal”, (Male TSH <4.4, and Female TSH < 2.5) and you have a TSH of 2.9 with symptoms of low thyroid, you will not be treated by a doctor who does not already know this difference.  He will say you are normal!  

The same normal for TSH is listed on the lab report for patients who are not on thyroid medication, and those who are on thyroid meds, BUT there is a different expected normal for patients who are on thyroid replacement, that is not reflected in the “normal levels”.  If you are on thyroid medication your TSH should be suppressed by the replacement hormones to less than 1.0.  If your doctor doesn’t know this, or forgets you are on thyroid replacement, then if your results come back with a TSH level of 2.0 while on thyroid medication,  your doctor will interpret the test saying that you are fine, when you really need more thyroid medication!  This is why a doctor should understand the tests they order, what conditions make the “normals”  ideal levels,  and the entire history of the patient that they are interpreting the tests for.  This is my understanding of why so many people are not treated with thyroid, or are given too low a dose.

This gender difference, and the lack of acknowledgment of them by the  major laboratories in the US is a major concern for Dr. Maupin. The two major labs used by physicians for blood testing have refused to add female normals to their results indicators listed on their reports.  This means that physicians who quickly read a lab report, frequently don’t respond to abnormal levels for women because they don’t see those normal ranges on the print out,  and therefore women are under treated for low thyroid.  Doctors must know and understand the difference in men and women’ normal thyroid stimulating hormone (TSH) to be able to diagnose hypothyroidism, and adjust their recommendations accordingly. It is an unnecessary and added risk for confusion and misunderstanding that leads to  inappropriate treatment.

I believe to rectify this lab reports should list the normal for men, women and for both sexes while on thyroid replacement.  This way doctors would be reminded to think about whether they are looking at a female, male or someone on thyroid replacement and more women would be treated for low thyroid instead of ignored and told it is all in their head!

TESTOSTERONE and estradiol for both men and women have a “normal” that is more of a guess, than a range of normal levels for young healthy men between 20 and 40.  Because there is controversy about Testosterone replacement for both men and women, what is listed as normal levels, is unusually very low.  It is not beyond the imagination that groups of medical “experts” get together and ask themselves how they can keep doctors from prescribing testosterone for either sex?  By making the supposed desirable levels so low that replacing the hormone will not solve the symptoms from that hormone.  Many numbers are manipulated in medicine to promote or dissuade patients and doctors from choosing a particular treatment.

It was about a decade ago that Quest listed the normal range of free T for women to be 0-.5, which is quite ridiculous no matter how you frame it.  When questioned by me the medical director did not have any idea how they came to their “normal” that doctors rely on, and 4 months later Quest changed the normal to 0.5 to 2.5. There was no rhyme or reason except to placate me and other doctors who questioned their normal.

Several articles have admitted that when measuring the low levels in women it is very difficult both to measure it and to repeat a test and get the same normal.  Most endocrinologists have not yet decided on what they think is “normal” for women, much less the T score (like bone density) for Testosterone when compared with healthy 29 year old women.

Men’s normals are adjusted for a man’s age which leave’s doctors comparing one abnormally low level of T found in aging men to be considered “normal”.  

This is what we have to come up against in deciding if a patient needs testosterone and how much they need.  The latest study of women and testosterone pellets decided that the only way to determine what blood level a woman needed was to raise the levels of T until all the symptoms of testosterone deficiency goes way!  There are too many variables and no certain ideal blood level, so the most reasonable way is to adjust according to symptoms.

These are the many things your doctor has to consider when diagnosing you, explaining the results to you and deciding how much of what hormone to give you.

I always go back to the many variations in a patient’s blood levels of all his or her hormones and then place them into the physiologic relationships that each hormone is affected by. In that way I can decide how to manage the hormone replacement for each patient who comes to my office.  In this way it is as much art as science, and decidedly improved day by day with experience.

This Health cast was written and presented by Dr. Kathy Maupin, M.D., Bio-identical Hormone Replacement Expert and Author, with Brett Newcomb, MA., LPC., Family Counselor, Presenter and Author.  


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