How do I read my hormone blood test results?
A hormone result is one moment, in one lab, compared against other people. To read it you need four things the report does not print: what time it was drawn, what you were taking, what its partner hormone was doing, and what your own number was last year. With those four, a page of results starts to make sense. Without them, "in range" and "out of range" tell you very little. This applies to a woman in perimenopause, a man wondering about testosterone, and a twenty five year old who was told everything looks fine.
What a reference range is
The range printed next to your result is built from a group of people the lab considers healthy. The lab takes the middle 95 percent of their results and calls that the range. Two things follow from this.
About one in twenty healthy people will land outside the range on any single test, purely by how the range is made. So one flag by itself is a reason to look again. It is no reason to panic.
The second point is the one that gets missed. In range means you resemble the group. It does not mean the number is right for you. If your result has moved a long way from where you used to sit, that is information, even when both numbers are inside the lines.
Ranges also differ by lab, method, age and sex, and sometimes by units. Testosterone can be reported in ng/dL or nmol/L. Compare results from the same lab when you can, and always check the units before you compare two reports.
Hormones keep time
Most hormones rise and fall across the day, the month, or both. A number without a time attached is half a result.
Cortisol is highest in the first hour after waking and lowest around midnight. A morning cortisol and an afternoon cortisol are different tests.
Testosterone is highest in the early morning, and eating lowers it for a few hours. This is why the Endocrine Society guideline asks for a fasting morning sample, repeated, before low testosterone is diagnosed. One afternoon reading after lunch should not put a man on treatment.
TSH runs higher in the early morning than in the afternoon. More on that in Issue 024.
Estradiol, progesterone, FSH and LH follow the menstrual cycle. Progesterone only says something useful about a week before your period is due. FSH and estradiol are usually read early in the cycle. In perimenopause these swing so widely from month to month that one draw can mislead, which is why NICE advises against FSH testing to diagnose menopause in women over 45 with typical symptoms.
A number without a time, a medication list and a partner hormone is half a result.
What you take shows up on the page
Biotin, common in hair and nail supplements, interferes with many lab methods. It can distort thyroid results and several other hormone tests. The American Thyroid Association advises stopping it at least two days before thyroid bloodwork.
Estrogen by mouth, in a birth control pill or hormone therapy tablets, raises the carrier proteins in your blood. Total thyroid hormone and total cortisol can read high because more is bound to carriers, while the free, usable amount has not changed much. The pill also lowers FSH and LH on purpose.
Steroid medications, including some inhalers, creams and joint injections, can lower your own cortisol reading. Opioid pain medication can lower testosterone and cortisol signals. Testosterone or anabolic steroids switch off LH and FSH.
Bring the full list to the person ordering the test. Stopping biotin for two days is safe for most people. Do not stop prescribed medication to get a cleaner result unless the prescriber tells you to. That includes thyroid medication, steroids and birth control.
Total and free
Many hormones travel through the blood attached to carrier proteins. Only the small unattached part, the free hormone, can enter a cell and do its job. A total result counts both.
This matters most for testosterone and thyroid hormone. The carrier for testosterone, called SHBG, rises with age and with oral estrogen. So a man in his sixties can have a total testosterone in range and a free testosterone that is low. A woman on the pill can show the same thing. The Endocrine Society advises checking free testosterone when the total is borderline or when something is known to change SHBG.
For thyroid, this is why free T4 is the standard test and total T4 is rarely used now.
Read them in pairs
Every gland hormone has a pituitary signal behind it. Read them together and the picture gets much clearer. I explained the loop in Issue 025.
TSH with free T4. High TSH with low free T4 is an underactive thyroid. High TSH with normal free T4 is an early or mild version, and it gets repeated before anyone acts.
LH and FSH with estradiol or testosterone. High signals with a low hormone mean the ovaries or testes are not responding. After menopause that is expected. Low or ordinary signals with a low hormone point to the brain and pituitary.
Fasting glucose with fasting insulin. Insulin is a hormone too, and glucose can look fine for years while insulin climbs to keep it there. That is Issue 012.
What I would do first
Make one folder. Every lab report you can find, in date order. Most patient portals let you download years of results. The trend is worth more than any single page.
On each report, write the time of the draw, whether you had eaten, the day of your cycle if you have one, and what you were taking. Nobody else is going to record this for you.
Repeat before you react. A single odd result, drawn at an odd time, gets retested under better conditions first. If your doctor asks you to fast and you take diabetes medication, ask how to handle your dose that morning.
Be careful with mail order hormone panels. Saliva tests are not recommended by menopause specialists for diagnosing menopause or adjusting hormone therapy. One real exception exists: a late night saliva cortisol is a legitimate test that doctors use when they suspect cortisol is too high.
I read folders with clients and I teach them to read their own. I do not diagnose, order tests or treat. When a pattern needs medical attention, I refer you and tell you what to ask for.
When to push harder with your doctor
Push when only half of a pair was run. A TSH with no free T4. A testosterone with no LH and FSH. A glucose with no insulin when your weight and energy have changed.
Push when a result is in range and you have moved a long way inside it, and you have symptoms. Bring the older results and show the direction.
Push when treatment is offered on one unrepeated test. Thyroid medication and testosterone are both long commitments. A second test costs little.
Push when your symptoms are plain and the answer is a lab you do not need. A woman over 45 with hot flashes and changing periods does not need a blood test to be taken seriously. Hormone therapy is the most effective treatment for hot flashes, and whether it suits you is a conversation for a menopause trained doctor.
Anything sudden or severe, such as chest pain, fainting, a racing heart or a severe headache, needs care that day.
FAQ
What does a reference range mean on a blood test?
It is the span that covers the middle 95 percent of results from a group of healthy people tested by that lab. Being inside it means you resemble that group. It does not prove the number is right for you, and one in twenty healthy people fall outside it on any one test.
What time of day should hormone blood tests be done?
Morning is best for most. Testosterone should be drawn early and fasting, and cortisol is usually measured in the morning unless your doctor wants a different time. For any hormone, use the same time at each test so results can be compared.
Can supplements change my hormone test results?
Yes. Biotin is the main one and can distort thyroid and other hormone results. Stop it at least two days before thyroid bloodwork and tell the lab or your doctor about every supplement you take.
What is the difference between total and free testosterone?
Total counts all the testosterone in your blood, including the part bound to carrier proteins. Free is the small unbound part your cells can use. When carrier proteins are high, as with age or oral estrogen, total can look normal while free is low.
Do I need a blood test to know if I am in menopause?
Usually no, if you are over 45 with typical symptoms. Hormone levels swing too much in perimenopause for one test to be reliable, so the diagnosis is based on age, cycle changes and symptoms. Testing is more useful under 45, and important under 40.
In good health,
Yvette Rose
Sources
- Bhasin S et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline, 2018.
- NICE. Menopause: identification and management (NG23).
- American Thyroid Association. Biotin supplement use can lead to false thyroid test results. Clinical Thyroidology for the Public, December 2018.
This is general wellness education and not medical advice, diagnosis or treatment. Talk to a qualified professional, especially if you are pregnant, nursing, taking medication or managing a condition.