Generally, only a blood test can definitively diagnose andropause.
After the age of 50, the average testosterone
level decreases at a rate of approximately one percent per year.
However, if only absolute testosterone levels are evaluated, many patients
with andropause will be missed. There may be an increased level of sex
hormone-binding globulin that binds the testosterone and makes less
of it available to the tissues. Also, as men get older, the daily rhythm
to the secretion of testosterone changes. Younger men have higher testosterone
in the morning, which then decreases as the day wears on. In older men,
this curve is flattened, leading to steady low
levels of testosterone throughout a 24-hour period.
Here are some issues regarding testosterone that are important to remember:
- It is not yet known what level of serum testosterone defines a deficiency in older men. Generally, it is accepted that two standard deviations below the normal values for young men is considered abnormal.
- A man may have large variations in his serum testosterone levels over time. Since he may have normal testosterone levels one day and have decreased testosterone levels the next, it is important to look at hormone levels over a period of time.
- In older men, affected organs may respond differently to androgens.
Not all men will need the same level of testosterone to maintain proper
function of their brain, bone, prostate, or muscle cells. Therefore,
it would be incorrect to say that there is one standard level of testosterone
that should be achieved by all men. Rather, the patient and the physician
work together to find the level of testosterone that is most effective
for the particular patient.
There remains significant controversy as to how best to measure testosterone levels and diagnose andropause. It is well accepted that if total testosterone is less than 200 ng/dl, a man will be considered as having a low testosterone level. If his total testosterone is greater than 600 ng/dl, low testosterone may be ruled out.
The analog-free testosterone method is the most commonly used test by most large commercial labs in the United States, but it is not considered a very accurate way of measuring testosterone. The best measurement of hormonal status is either free testosterone or bioavailable testosterone. These measurements may only be available through specialty laboratories.
It is important to remember that there is significant variation in the recommendations of what tests should be used in order to establish a biochemical diagnosis of andropause. However, it is widely accepted that the blood work should be done in the morning before ten o'clock to capture the potential peak values.
Watch an educational animation video on sexuality and aging.