Low testosterone · Telehealth for men · Canada & USA
What labs should I ask for besides total testosterone?
Start with a morning total testosterone, repeated on another day if it’s low. Then add the tests that help explain why: free testosterone and SHBG, LH and FSH, and often estradiol, prolactin, hematocrit and PSA (where age-appropriate), plus thyroid, blood sugar (A1c) and lipids. We walk you through which ones fit your situation, and ranges differ from lab to lab.
Part of our low testosterone and andropause guide for men in Canada and the USA.
Timing comes first: morning, fasting, repeat
Testosterone is highest in the morning, falls through the day and varies from one day to the next. A single afternoon reading can be misleading. The Endocrine Society guideline (2018) advises early-morning, fasting total testosterone, measured on two separate mornings, using an accurate and reliable assay.
Early morning
Reference ranges are based on morning samples, so a morning draw is the fair comparison.
Fasting
Food and sugar can lower measured testosterone, which is why guidelines suggest a fasting sample.
Repeat if low
A second morning test confirms whether it is consistently low.
Tell the clinic
Mention biotin (vitamin B7) supplements, which the FDA has warned can interfere with some lab tests, plus any steroid or testosterone use and recent illness.
The core trio: total T, free T and SHBG
Most testosterone in your blood is attached to carrier proteins, mainly SHBG. Only a small part travels free. Total testosterone counts all of it. Free testosterone is the portion that isn’t tightly bound. SHBG shows how much carrier is in the way, which changes how a total number should be read. With total T, SHBG and albumin in hand, our free testosterone calculator works out the free part and converts nmol/L and ng/dL.
Total testosterone
The first test. It shows the overall amount of testosterone in your blood, bound and free together.
Free testosterone
Helps when total testosterone is near the lower limit or SHBG may be unusual. The Endocrine Society guideline advises measuring it by equilibrium dialysis or estimating it with an accurate formula.
SHBG
Body weight, age, and thyroid and liver conditions can push SHBG up or down. That can make total testosterone look lower or higher than the amount your body can actually use.
Finding where the problem sits: LH, FSH, prolactin and estradiol
Once low testosterone is confirmed, the next question is why. Your brain and pituitary gland send LH and FSH to the testes, which make testosterone. These tests help show whether the slowdown is in the testes, in the signal from the brain, or somewhere else.
LH and FSH
High values alongside low testosterone point toward the testes. Low or unexpectedly normal values point toward the signal from the brain. They also show how much your own system is producing, which matters if fertility is a concern.
Prolactin
A pituitary hormone. Raised levels can lower testosterone and sex drive, and some medications raise it. It is often added when LH is low.
Estradiol
A form of estrogen the body makes partly from testosterone. It is sometimes checked for context, read alongside your symptoms, not on its own.
If children are a goal
Ask about a semen analysis. It shows sperm production directly, which testosterone levels don’t.
Safety and baseline labs: hematocrit, PSA, liver and kidney
If testosterone therapy is ever on the table, a baseline is taken for the things it can affect, and the same tests are used to monitor afterwards. They also help spot other conditions.
Hematocrit or CBC
Hematocrit is the share of your blood made up of red blood cells. A high value is a reason for caution with testosterone therapy. A low one can point to other conditions.
PSA, where age-appropriate
Whether and when to check PSA depends on your age, family history and preferences. We help you decide whether it fits, and it is usually part of the conversation before any testosterone therapy.
Liver and kidney (CMP)
A general metabolic panel shows how your liver and kidneys are working. It gives context for other results and for any medication.
Whole-body context: thyroid, blood sugar, lipids and more
Fatigue, low drive and weight gain have many causes. These tests help show what else might be involved, and they matter for your general health anyway.
Thyroid (TSH)
An under- or overactive thyroid can cause tiredness, weight change and low mood, and it can change SHBG.
A1c and glucose
Shows how your body handles blood sugar. Diabetes and insulin resistance are associated with lower testosterone.
Lipids
Cholesterol and triglycerides are a standard check of heart health and useful context if testosterone therapy is discussed.
Vitamin D
A general-health marker that is often included alongside the others.
Iron studies, if indicated
Too much iron storage can affect the pituitary and testes, so ferritin and related tests are sometimes checked in some men.
A sensible order for testing
You don’t need everything at once. We help you choose the order that fits you.
- Step 1
Morning total testosterone
Fasting and early, often with SHBG and free testosterone alongside.
- Step 2
Repeat if low
A second morning test on a different day confirms whether it is consistently low.
- Step 3
Add the “why” tests
LH, FSH, prolactin, estradiol, thyroid, A1c and anything your history points to.
- Step 4
Baseline and review
Hematocrit, PSA where age-appropriate and a metabolic panel, then we go through everything with you. See TRT or fix the causes first.
How to ask for them
Bring a short list, and ask what each result would change about what happens next. If a test wouldn’t change the plan, it is fair to ask why it’s needed. In Canada, what public health insurance covers varies by province and situation. In the USA it varies by plan. Ask about cost before you book.
A short script
- Could we do a fasting, early-morning total testosterone, and repeat it if it’s low?
- Should we add free testosterone and SHBG?
- Would LH, FSH and prolactin help us understand the cause?
- Is it worth checking thyroid, A1c, lipids and a blood count at the same time?
- If we ever consider treatment, which baseline tests should I have first?
- What would each result change about what we do next?
Why your number may not match the one you read online
Reference ranges differ from lab to lab. They depend on the assay, the equipment and the group of people used to set them. The same result can be flagged normal at one lab and low at another. That is why the range printed on your own report is the one that counts, and we read it with you alongside your symptoms and repeat results.
Sources
- Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab 2018;103(5):1715-1744. doi.org/10.1210/jc.2018-00229
- US Food and Drug Administration. Biotin interference with lab tests (FDA: biotin in supplements can cause incorrect results). fda.gov
Frequently asked questions
What is the first test to ask for?
A total testosterone test on an early-morning, fasting blood sample. The Endocrine Society guideline (2018) advises repeating a low result on a second morning before drawing conclusions, because levels vary through the day and from day to day.
Do I need free testosterone as well as total?
Sometimes. The Endocrine Society guideline advises measuring free testosterone when total testosterone is near the lower limit of normal or when something that alters SHBG may be present, such as a change in body weight or a thyroid or liver condition. We walk you through whether it adds anything in your case.
Why check LH and FSH?
They show where in the system a low testosterone result may be coming from: the testes themselves, or the signal from the brain and pituitary gland. They also show how active your own production is, which matters if you may want children.
Should I get a PSA test?
It depends on your age, family history and preferences, and we help you decide whether it fits. If testosterone therapy is ever being considered, PSA is usually part of the baseline conversation for men of an age where it is appropriate.
Do reference ranges differ between labs?
Yes. Ranges depend on the assay, the equipment and the group of people used to set them, so the same result can be flagged differently at two labs. That is why the range printed on your own report is the one that counts, and we read it with you alongside your symptoms and any repeat result.
How does Odin Health Labs work with my doctor?
Odin Health Labs is a telehealth service for men in Canada and the USA with low testosterone (andropause) symptoms. A free call helps you work out which labs to ask for and what to do with the results. We review your labs with you, build your plan and track your progress, and we can share your plan and results with your doctor if you choose. See our low testosterone overview and our Privacy Policy.
Want help deciding what to ask for? Start with a conversation.
A free call helps you work out where to start and what to ask for.