What Is A Normal Testosterone Level?
When men wonder if they have low T, the next question is always, “What is a normal testosterone level, anyway?
Often, when you go to a lab for a testosterone test, you will be shown a “normal range” of around 300 to 1200 ng/dl (nanograms per desilitre). Typically, this refers to the total testosterone in circulation in your blood.
Lab testosterone values are not normal values.
Labs often refer to different ranges as normal. Most labs don’t break down these ranges by age. So, 40-year old men are lumped in with 80-year olds. Ranges also do not separate out men who have testosterone-lowering health conditions, such as obesity. An accurate definition of normal testosterone must take age and health into consideration, so the ranges provided by labs and used by most doctors are not really useful.
You have three testosterone levels, not just one.
The total level of testosterone in your blood includes three types of testosterone : free, albumin-bound, and SHBG-bound.
- Free testosterone is the amount of testosterone left over in your blood after your body’s cells have absorbed the testosterone they need to function normally. Your cells absorb testosterone by binding to it. The unbound testosterone, about 2-3% of the total amount, is free testosterone and can be functionally available.
- Albumin-bound testosterone and accounts for about 40% of testosterone in circulation, and is thought to be also bioavailable because the protein bond is relatively weak.
- SHBG-testosterone accounts for about 60% to 70% of the testosterone produced by your body. Sex hormone-binding globulin (SHBG) is a protein molecule produced mostly by the liver that carries functions like a hormone.
Clinical research suggests that symptoms of low T appear when total testosterone levels drop below 320 ng/dl. But your biologically available testosterone can be more important than your total testosterone when being treated for low T, because biologically available testosterone is largely responsible for a sense of wellbeing and energy. So you could have a high total testosterone level and yet still be testosterone deficient.
There is no standardized way to test for low T.
There are about a dozen methods of testing for testosterone. These are broken into two basic types:
- Automated immunoassays and radioimmunoassays, which use antigens to measure specific substances in blood samples.
- Liquid or gas chromatography-mass spectrometry, which measures testosterone by molecular weight and fragmentation patterns.
Most doctors and clinics test testosterone levels using immunoassays, which are intended to provide:
- A direct measurement of total testosterone
- A direct measurement of free testosterone (bioavailable)
- A direct measurement of SHBG testosterone
- A direct measurement of albumin-bound testosterone (bioavailable)
- Total bioavailable testosterone is calculated mathematically by measuring the three types of testosterone.
Blood tests are drawn in your doctor’s office and are usually processed by an independent lab. These labs use commercially available immunoassay tests, but there is a lack of standardization between tests and procedures that leads to inconsistency. Immunoassays can be relied upon for severe cases of low T, but not more subtle ones. For men with borderline low T, liquid and gas chromatography-mass spectrometry testing is the gold standard.
Sophisticated HRT clinics will also run associated tests for luteinizing hormone (LH) and follicle stimulating hormone (FSH). Produced by the pituitary gland, these hormones stimulate the gonads to produce testosterone. If they are low, then synthesis of testosterone will also be low, confirming a diagnosis of low T.
General definitions of normal testosterone are not clinically important.
Testosterone ranges among men are too heterogenous to allow for a simple definition of what is normal testosterone. The ranges used by most doctors are based on broad samples of men, often using inconsistent immunoassays. Even among men of the same age, there can be variations in diet, exercise, and sleep that affect testosterone levels. If a man is late for his test appointment, simply hurrying from the parking lot to the office will temporarily boost his testosterone, giving an inflated test result.
A doctor with experience in treating low T can weigh many variables based on experience that are not reflected in broad averages. If you are diagnosed with low T, you will have corresponding physical symptoms such as fatigue and loss of libido. Look at your beginning test results and at your results during hormone therapy, and compare your symptoms. If you are feeling good – like your “old self again” – then this is what is normal for you.