Don’t Trust Your Lab’s Reference Ranges! – Part 2

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The “normal” or “reference ranges” provided by lab companies are not always the healthiest values.

A doctor must have an ideal, healthy range for any test which they is using to diagnose a patient.  Diagnosticians cannot decide whether this ideal level or “reference range” is accurate without a great deal of scientific investigation, so he or she uses what is listed on the lab report which results in misdiagnoses.  Blood panels are expensive and should have the information listed with the result that explains what circumstances make the test fall into the healthy and asymptomatic range.   This is a problem with most large national labs, and it is leading to great numbers of misdiagnoses.  Let me give you some examples of the problem with how labs are reported:


Female Estradiol

Published Lab Reference Range

Postmenopausal: < or = 10 pg/mL

Estradiol is the female estrogen that disappears after menopause.  Before menopause the average blood level of E2 is 60-250 pg/dl depending on the pre-or post-ovulation stage of the menstrual cycle. That range of estradiol is healthy for women.  Lack of estradiol (which occurs at menopause and creates disabling symptoms) is unhealthy for women and the reference range should show that lack of E2 is “abnormal” and not within reference range.

The lab considers that Estradiol levels are “normal” after the age of 40, if they are <60, and even zero. This implies that women are healthy and without symptoms when they have no estrogen.  When a PCP who doesn’t look at hormones every day looks at the ref range without adjusting her interpretation for stage of pre-or post-menopause. They may think that women without estrogen is healthy and without symptoms. Women who have their estradiol replaced after menopause are not symptomatic when they have an Estradiol between 60-250 pg/dl, but they have hot flashes, night sweats, anxiety attacks and painful intercourse if their E2 is less than 60 pg/dl. The blood level of Estradiol less than 60 should be placed in the out-of-range column.


Female FSH                                                  Female LH

Published Lab Reference Range                         Published Lab Reference Range

Postmenopausal: 23.0 – 116.3 mIU/mL          Postmenopausal: 10.0 – 54.7 mIU/mL

FSH/LH are 2 pituitary hormones that do not cause symptoms when they are under 23 and 10 respectively.  If a woman is premenopausal, or on sufficient estrogen replacement after menopause their FSH and LH are low, and they are asymptomatic.  We test FSH and LH hormones to find out if is a patient is menopausal.  If her FSH is over 23, and estradiol is under 60 then the patient is menopausal OR they are taking enough Estradiol to suppress their LH and FSH levels to normal (less than 23/10 respectively).

Why do the labs consider very high FSH and LH levels to be “normal” or “in range” even though these elevated hormones cause many symptoms in menopausal women? High LH and FSH are not healthy or normal, but the lab says that anyone over 40 is normal with these extremely high FSH and LH. None of this is reported or mentioned on the lab sheet.  The reference range for FSH and LH is listed under “Normal “if the FSH and LH are higher than 23/10, even if the FSH is extremely high and the patient is symptomatic! Recently studies have shown that High LH and High FSH levels themselves cause osteoporosis and dementia.  It is now even more important to give a woman enough Estradiol to suppress these 2 hormones.

Female Testosterone Free                     

Published Lab Reference Range

Postmenopausal: 0.2 – 5.0 pg/mL


Free Testosterone levels for women: Finding a test that can correctly report testosterone levels when they are in the low range, such as female blood levels, is difficult.  Testing for accurate female testosterone levels to compare with a reference range, has many problems. For instance, no one really claims to know what the “normal” level of free T is for is for young healthy women.  Large scientific studies looking at free T levels in young healthy women are just now commencing.

However even though the test for free T in women doesn’t have a reliable, repeatable blood level based on pre-menopausal healthy women, I still use it for a marker to tell me if a patient’s free testosterone level improved along with the resolution of her symptoms. I was trained to only test for the free T with the normal number for young premenopausal women is > 7 pg/ml.


Male Testosterone Free

Published Lab Reference Range: 35.0 – 155.0 pg/mL

T and free T for men: The reference range for men is very low. The way the lab obtains these numbers for their reference range for testosterone is by using the blood levels of men who come to their lab to get their testosterone drawn. This results in the “reference range” not representing healthy young men, but representing “sick men” of all ages, usually old men, who are having their blood drawn at the lab for other reasons. Testosterone and free T decrease with illness and with age.  The way the reference range of T and T-free is skewed to a much lower level than is optimal. With a low range misrepresenting the ideal, men who have low T and free T and are symptomatic and are not treated.  The range I use is 400-1500 the average for healthy young men between 20-40 years old.  No man feels good with a total T of 234-400, the low end of the range considered normal for men by Quest and Labcorp. This misrepresentation is preventing many men from treatment.

The way they derive their blood range for total T and free T is not scientifically sound, and that affects whether a man is treated or not. Physicians who treat aging men know and should know that testosterone decreases as a man age (after age 40), and becomes symptomatic at age 55, on average. Most men are symptomatic when their free T falls below 129, not below 35.

All testing of blood levels of hormones that decrease with age should be compared to those levels of young healthy people of the same gender. I like to compare hormone tests to the well accepted interpretation of bone density.  Bone density decreases with age just like the sex hormones.   Because bones decrease in density with age, we compare all women to 29-year-old females who have normal bones.  This same scientific method should be used for sex hormones that decrease with age. We should compare sex hormones to the blood levels of healthy young men or women of the same gender.

The faulty basis judging a man’s adequacy of testosterone is also used for evaluating IGF-1 (Growth hormone) and all the sex hormones. It looks like we have a lot of work to do!


Male and Female IGF 1

Published Lab Reference Range: 50 – 317 ng/mL

IGF-1 is age-adjusted on the lab sheet to the age of the patient, not compared to normal healthy patients of the same gender. IGF-1 measures growth hormone which is a hormone that is “normal” before age 40 and declines thereafter. To know if you have low growth hormone a patient should be compared to healthy people who are young, under age 40. An example of why this comparison don’t work for aging patients: the IGF-1 of one 70-year-old compared to another 70-year-old does not tell you if the hormone is less than optimal, or just normal for your age. IGF-1 should be compared to 20–40-year-olds, not the average for your age!

Estrone is an adrenal estrogen.  It is normally ½ of the Estradiol level in women before they are 40 and women maintain a ratio with Estradiol (the ovarian estrogen) of E2:E1 of 2:1. The numbers are not significant, the ratio is. This is ignored on lab tests.

Insulin level is dependent on whether the patient is fasting or not.  Both labs only list the non-fasting range, even on patients who ARE FASTING.  This over site leads to fewer patients who have insulin resistance being diagnosed and treated, which leads to more patients with AODM.

Example: The range that is on the lab report for both Quest and Labcorp is a non-fasting range (2-24), but the healthy fasting the range is 2-10. (Epocrates). However, the fasting range is not listed on the Lab report even though all of my patients are fasting! This causes me to write in the normal fasting blood level of insulin.

Thyroid Panel is misleading and is not accurate in many cases:


Male and Female T3, Free and T4, Free

T3 – Published Lab Reference Range: 2.3 – 4.2 pg/mL

T4 – Published Lab Reference Range: 0.8 – 1.8 ng/dL


TSH (.45-4.5) is only accurate for patients who are NOT on thyroid medicine. If you are on thyroid medicine, to be accurately replaced your TSH should be less than 1.0 (read the insert of Synthroid, the most widely prescribed thyroid replacement.  There is no separate normal for patients on thyroid medication.

For patients NOT on thyroid medicine TSH is not updated for new research. In the last 10 years TSH has a been found to be more accurate with a smaller range of normal, 0.45-2.5.  This has not been reflected in the TSH of both labs.

Free T4 levels reported on lab reference ranges have unscientifically been adjusted over the last 15 years without true scientific research. This change is based on obtaining reference ranges from the group of sick people getting their blood drawn at a particular lab, and not a group of young healthy people who don’t have any symptoms of low thyroid.  This is a cost saving effort that has devastating effects on women especially who have symptoms of low thyroid, but who do not have a free T4 outside the reference range, so they are not treated. FreeT4 is 0.8-1.8 ng/dl is reported on lab reports as the “new normal”, when the range based on a young healthy group of people is 1-2.5 ng/dl.

We know that the group of people who go to the lab for bloodwork are generally older, sick, and may have thyroid disease. They are not a group of subjects to use to define “normal” or “healthy”.   Making this situation worse, thyroid function decreases when a patient is ill, so ranges obtained from this group of patients is not “normal or healthy”.  The medical director of Quest has confessed to using these sick patients to obtain their reference ranges for thyroid.

Free T3 levels have lowered over the last 15 years without scientific basis. The same issue occurs with free T3 as with free T4.  The range is now 2.3-4.2, pg/ml. and has lowered every few years over the last 15 years.  The range that is based on young healthy patients is 3.0-4.5. This affects many patients who are on thyroid medication whose doctors lower their dose if they are between 4.2 and 4.5, and patients are not diagnosed if they fall into the range between 2.3 and 3.0.

 This slow, unscientific lowering of the ref range by lab companies based on their sick population has negatively affected many women who need appropriate thyroid replacement and is unscientific.



The reference ranges listed by the largest labs in the US are unscientifically derived and misleading.  It makes it impossible for patients to interpret their own labs appropriately.  These inaccurate “normal” referred to as “reference range” also make it impossible for young inexperienced doctors and busy doctors who are quickly going through the labs but not really looking at the changes in the numbers but whether the lab lists the results in the “in range” or, “out of range” columns.

These numbers are expensive to order for patients and doctors and should be reported with accurate “normal” that have the most recent research applied and who use normal healthy young people to derive the “reference ranges”.

This Health cast was written and presented by Dr. Kathy Maupin, M.D., Bio-identical Hormone Replacement Expert and Author.  (314) 993-0963.

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