Your lab results arrived, and one line says testosterone. Maybe a flag sits beside it, or maybe it looks normal while you still feel off. Your testosterone test results make sense when you read the lines together. Here is what each line on a typical report measures.
Total testosterone is the first number on your report
Total testosterone counts all of the testosterone in your blood. That includes the share attached to proteins and the small share that moves freely.
Labs in the United States report total testosterone in nanograms per deciliter (ng/dL). Each lab prints its own reference range beside your result, and those ranges differ from lab to lab. The American Urological Association uses 300 ng/dL as its cutoff for diagnosing low testosterone. It also asks for two early morning tests on separate days before that diagnosis.
A reference range shows what is common. Where you feel your best is a separate question. Following our WorldLink Medical training, we like to see total testosterone between 700 and 1,400 ng/dL. Everyone is different, and we set your own target from how you feel and what your labs show. That target sits apart from the reference range your lab prints.
Free testosterone is the share your body can use
Most of your testosterone rides through the bloodstream bound to one of two proteins. Sex hormone binding globulin, or SHBG, holds on tightly. Albumin holds on loosely. Your tissues can still pull testosterone away from albumin.
Free testosterone is the small share attached to neither protein. Your cells can use it right away.
Many labs calculate free testosterone from your total testosterone and your SHBG. Some labs measure it directly with a specialized method called equilibrium dialysis. Your report may also list bioavailable testosterone. That value adds the loosely bound share to the free share.
How SHBG locks testosterone away
SHBG decides how much of your total testosterone stays locked up. When SHBG runs high, more testosterone stays bound. Your total can look normal while your free testosterone runs low. SHBG tends to climb with age, and an overactive thyroid or some liver conditions can push it up as well.
When SHBG runs low, the picture flips. Your total can read low even when your free testosterone sits closer to normal. A low SHBG deserves a closer look, and insulin resistance is one common cause.
Many people with symptoms of low testosterone and a normal total find the explanation in their SHBG and free testosterone.
Insulin resistance and diet move your SHBG
Your liver makes SHBG, and your metabolic health changes how much it makes.
With insulin resistance, your cells stop responding well to insulin. Your body then releases more insulin to keep your blood sugar steady. A review in Trends in Endocrinology and Metabolism reports that low SHBG often goes along with insulin resistance. The same review links low SHBG to a higher risk of type 2 diabetes.
In laboratory studies of liver cells, glucose and especially fructose drove the cells to build fat and make less SHBG. Those results come from cells in a dish, and studies in people are more limited. They still suggest that a diet heavy in sugar and refined starch may play a role in your SHBG.
Body fat matters in a second way. Fat tissue converts some of your testosterone into estrogen.
For these reasons, we read your testosterone next to your metabolic health. When insulin resistance improves, SHBG often rises with it. Meals built on protein and fiber help, and regular strength training helps too. Our article on metabolic health and insulin resistance covers that side in more detail.
The time of your blood draw changes your result
Testosterone follows a daily rhythm, and your levels peak in the morning. For a first test, plan a morning blood draw.
If you already use testosterone therapy, time your draw from your last application. At Contours, we like to test 2 to 3 days after an injection, or about 4 hours after you apply a cream. Testing at the same point each time lets us compare your results fairly.
Supplements can skew the test itself. Biotin, a common hair and nail supplement, interferes with some lab methods. Tell your provider about everything you take before your draw.
A few other things can pull a result down for a while:
- a short night, or several nights of poor sleep
- a recent illness or infection
- a hard training block or a steep cut in calories
- some medicines, such as opioid pain relievers and prednisone
These dips usually pass once the cause does. A retest on an ordinary week gives a truer reading, and it keeps one bad night of sleep from steering your care.
The rest of the panel completes the picture
Panels vary from one provider to the next. At Contours, we test more than testosterone, and your first panel starts with these lines:
- Total and free testosterone, with SHBG. The sections above explain these numbers.
- DHEA-S. Your adrenal glands make this hormone. Your body uses it as a building block for testosterone and estrogen.
- CBC, a complete blood count. This counts every type of cell in your blood. Testosterone therapy can raise your hematocrit, the share of your blood made of red cells.
- Liver and kidney function. These show how well the organs that process hormones and medicines are working.
- Lipids. Your cholesterol numbers give a baseline for heart health.
- PSA, for men. Prostate specific antigen gives a baseline for prostate health before any treatment starts.
Later tests compare against these baselines. If your hematocrit rises on therapy, your provider sees the change against your starting point.
Women read these numbers on a different scale
Women make testosterone too, in far smaller amounts. Female reference ranges sit far below male ranges, and labs need sensitive methods to measure numbers that small. Our guide to testosterone therapy for women explains how those numbers work.
Your symptoms count as much as your numbers
A lab value cannot tell anyone how you feel. Some people feel tired and foggy with a total in the normal range. Others sit near the cutoff and feel well.
That is why we weigh your symptoms and your labs together. When energy is your main concern, our article on TRT and energy goes deeper.
What happens after your results at Contours
At Contours, your results start a conversation with a provider. Here is roughly how it goes:
- Day 1: a private conversation about your symptoms and your goals.
- Week 1: your comprehensive labs.
- Weeks 1 to 2: a results review with your provider. If your labs and symptoms support therapy and you choose it, treatment may start after that review.
- Weeks 6 to 8: follow-up labs and fine tuning.
- Every 3 to 6 months: ongoing monitoring and adjustments.
The timing can shift with your results and your schedule. Every step works from your own numbers.
Read more about testosterone therapy at Contours. When you are ready, start the conversation and bring your latest results. We will go through them with you.