Free Testosterone Test

What is Testosterone?

Testosterone is the main sex hormone produced in men. It is mostly made in the testes (or testicles), although a small amount is made in the adrenal glands. A small amount is also made in the ovaries and adrenal glands of women.

In men, testosterone's primary role is development of the sex organs and secondary sexual characteristics, such as sperm production, facial/body hair growth (and balding), deepening voice, bone and muscle mass/strength, body fat distribution, sex drive (libido), and mood. In women, testosterone's roles include ovarian function, fertility, libido, and bone mass/strength.

The pituitary gland controls testosterone levels in the blood by releasing hormones, which are carried in the blood to the testes, ovaries, and adrenal glands. Pituitary hormones then stimulate these organs to produce testosterone. Blood testosterone level is controlled by the pituitary releasing fewer hormones when blood testosterone levels increase above normal and release more hormones when blood testosterone levels decrease below normal. In this feedback system, the pituitary gland is controlled by hormones released by hypothalamus in the brain.

What is a Free Testosterone test?

The blood contains testosterone bound to proteins and testosterone not attached to protein (called free testosterone). Testosterone is mostly bound to the proteins, sex hormone binding globulin (SHBG), and albumin. However, testosterone that is bound to albumin can detach becoming free. About 2-4% of testosterone is free testosterone. A free testosterone test measures the blood level of both free and albumin-bound testosterone; this is the portion that is bioavailable. Only free testosterone can enter most of the body's cells. Tests for both total and free testosterone can be done but require different samples using our self-sampling service. Click here to read about the total testosterone test.

Why is a Free Testosterone test important?

A free testosterone test alongside a total testosterone test is among the first tests to be carried out if you have symptoms indicating that testosterone levels may be outside the normal range. In male patients, free testosterone levels can be better at indicating a true testosterone-related deficiency (e.g., due to a low SHBG level) than total testosterone levels, which may be falsely low due to another health problem (e.g., obesity may lead to insulin resistance, which lowers SHBG levels leading to low testosterone levels).

Abnormal testosterone levels in men can be due to a condition affecting testosterone production. Low testosterone levels may be the result of a genetic disorder such as Klinefelter syndrome, abnormal sex organ development or a testicular injury. Low testosterone levels in men and women can indicate hypothalamus or pituitary gland involvement (e.g., Addison's disease, tumours) or removal of the testes/ovaries.

In men, low testosterone levels may also be the result of autoimmune diseases, kidney and liver disease, metabolic syndrome, infection (e.g., COVID-19, mumps virus), and AIDS/HIV. Therapies damaging the testes (e.g., chemotherapy or radiation) and medicines such as opioid pain medications, cimetidine (treating heartburn and stomach ulcers), and some anti-fungals (ketoconazole) and antidepressants (fluoxetine) may also lower this hormone. In women, testosterone levels are lowered by oestrogen therapy.

High testosterone levels can be a sign of testicular cancer in men, ovarian cancer or polycystic ovary syndrome in women, and adrenal gland cancer in either sex.

At The Online Clinic, your results are interpreted by a doctor and made available via your patient dashboard. Advice is provided on the next course of action required (if any).

Who should monitor their Free Testosterone?

Testosterone testing is relevant to all people who experience symptoms associated with abnormal testosterone levels. Men may have a low sperm count, erectile dysfunction, loss of hair on head, face and body, muscle mass loss, breast enlargement, and irritability; women may experience irregular menstrual cycles, vaginal dryness and breast tissue changes. Signs of below normal levels in men and women may include fertility problems, loss of libido, weakening/loss of bone mass/muscle mass, depression and poor concentration.

However, when a man's hormone level is above normal, symptoms may include a low sperm count, testicle shrinkage, prostate enlargement, weight gain, increased muscle mass, mood swings, and increases in signs of cardiovascular disease (e.g., high blood pressure, high blood cholesterol). Women with high testosterone levels can have irregular menstrual cycles, reduced fertility, breast shrinkage, weight gain, male-pattern baldness, excess face and body hair, thicker skin, and depression.

Please note that the Free Testosterone test is not the recommended test for female patients monitoring testosterone levels during treatment with testosterone replacement therapy. The correlation with biological activity of testosterone has not been confirmed, so the recommendation is to use total testosterone to monitor levels in this patient cohort.

How to test for Free Testosterone?

Blood testosterone levels vary during the day and are higher earlier in the day. The clinic will instruct you on when to collect a blood sample, which is from 7 am to 11 am.

Free testosterone tests require a small blood sample, which can be done by you using a test kit supplied by The Online Clinic. The kit is easy-to-use and comes with full instructions on collecting the blood sample. In short, clean your little finger tip, prick the skin on the clean finger-tip with the lancet, and collect the blood drops up to the top line in the collection tube. Repeat using the other little finger tip if blood drops stop forming to complete the blood sample collect. Seal the collection tube and gently invert it 5 to10 times. Stick the filled-in tube label to the collection tube, and place in the packing wallet for sending back via tracked mail, which is included as part of the kit. Results take 3 working days from the point the sample is received at the laboratory.

Patients applying topical hormone preparations must use disposable gloves for the application to the skin. Residue from these gels and creams can get into the blood sample collected via the finger prick method and produce a distorted result. The disposable gloves are therefore an essential precaution.

What are normal Free Testosterone test results?

Age, medical history, sex, treatment, and test methods can all alter free testosterone levels and therefore test results, so test results will be interpreted for you by your doctor. Free testosterone levels are calculated from your levels of total testosterone, SHBG and albumin, using an algorithm.

Your doctor at The Online Clinic will receive the test results and explain what your results mean.

How to maintain or achieve good Free Testosterone levels

Testosterone levels will decline with age, but eating healthily, maintaining a healthy body weight, regularly exercising and having plenty of rest while avoiding stress will maximise your chances of healthy testosterone levels.

Any symptoms of low or high testosterone should be investigated by your doctor, which will possibly involve a free testosterone test. Testosterone therapy may help some symptoms, such as low libido, erectile function, decreased bone mass/muscle mass, and depression. However, you may need to make lifestyle changes to help improve other issues, such as low blood sugar and cholesterol levels, and quality of life.