Total testosterone

Testosterone is the main male sex hormone, but everyone has it. In men the testes make it, driven by LH from the pituitary; in women a tenth to a twentieth of that amount comes from the ovaries and the adrenal glands. It builds muscle and bone, drives desire, energy and drive, keeps the production of red blood cells up and, in men, helps decide sperm production. Most testosterone in your blood travels bound to protein: tightly to SHBG and loosely to albumin. Only the free part, a few percent, can enter the cell and do its work. Total testosterone adds everything up, bound and free. That is the standard measurement and usually enough, but with a high or low SHBG the active part shifts without the total moving, and then SHBG belongs beside it. Your report shows testosterone in nmol/L, with one range for men and one for women that do not meet: where the labs overlap it runs from 9.0 to 27.3 nmol/L in a man of 20 to 50 years and from 0.3 to 1.7 nmol/L in a woman of the same age. The range falls slightly with age, and it depends on the time of day: testosterone is highest in the morning and a quarter lower in the afternoon, so have blood drawn before ten.

For men testosterone is one of the most honest lifestyle values on the report. It falls with belly fat, because fat tissue converts testosterone into oestradiol and insulin resistance suppresses production. It falls with lack of sleep, because most testosterone is made during sleep; a week of short nights already makes a noticeable difference. It falls with lasting stress, with plenty of alcohol, with overtraining and eating too little, and with sleep apnoea. And it falls slowly with age, about one percent a year from around thirty, though in fit men much less than assumed. That makes a low testosterone in a man of forty usually not a matter of a hormone that has run out, but of a body that does not make it because the conditions are not right. Little desire, little energy, less muscle and more belly are the complaints, and they reinforce each other: less testosterone gives more belly fat, and more belly fat gives less testosterone. Anyone who breaks that circle, with losing weight, strength training and sleep, usually sees the number come back. In women testosterone plays a different role: it carries desire, energy and muscle, and the most common problem is too much rather than too little. A raised testosterone in a woman usually belongs to PCOS, with an irregular cycle, excess hair growth and acne, and there too insulin resistance sits underneath. Testosterone as a medicine is there for men with a persistently low testosterone on two mornings and symptoms, once LH has shown where it lies. It is not a remedy for tiredness or getting older: it shuts down production of your own, reduces fertility and thickens the blood, and in most men with a moderately low number lifestyle works better and without that price.

A low testosterone in a man is, in order of how often it occurs: drawn too late in the day or after a short night, belly fat and insulin resistance, lack of sleep or sleep apnoea, lasting stress, plenty of alcohol, overtraining or eating too little, and age. Then medicines: opioids, prednisone and anabolic steroids, which shut down production of your own. Rarely it is the testes themselves or the pituitary, and LH keeps those two apart: a high LH with a low testosterone is the testes, a low or normal LH is the signal from the brain, and that is almost always the reversible part. A high testosterone is rarely a problem in men and usually testosterone from outside, from a gel, injection or anabolic steroids. In women a raised value is usually PCOS; a strongly raised value, a multiple of the range, is rare and calls for investigation of ovaries and adrenal glands. A low testosterone in women is rarely measured and rarely treated: the pill lowers it via SHBG, and that is then the intention. The levers are strong and concrete in men. Losing weight around the middle is the biggest, and ten percent weight loss already lifts testosterone noticeably in a man with excess weight. Strength training, because muscle demands and makes testosterone, and heavy exercises with large muscle groups work best. Seven to eight hours of sleep, and having sleep apnoea treated if it is there. Less alcohol, and enough food for what you train: an energy deficit shuts the signal down. In women with PCOS, losing weight and less sugar and fast carbohydrates work the same way, through the insulin resistance underneath. Never read testosterone on its own. SHBG shows how much of the total is free; in a heavy or ageing body the total tells only half the story. LH shows where a low value comes from. In men oestradiol belongs beside it when there is belly fat, in women the cycle day. And repeat a low value on a second morning before drawing anything from it.