The international medical societies European Association of Urology (EAU), International Society for the Study of the Aging Male (ISSAM), International Society of Andrology (ISA) issued recommendations on the definition, investigation, treatment and follow-up of men with late-onset hypogonadism.
If symptoms of testosterone deficiency are present, the doctor will investigate them using various diagnostic procedures. These include:
ISSAM, EAU and ISA suggest that the most widely accepted parameters to establish the presence of hypogonadism are the measurement of total testosterone and free testosterone calculated from measured total testosterone and SHBG, or measurement of free testosterone by an equilibrium dialysis method.1
Depending upon these test results, supplementary tests may be required. These include a bone density test for suspected osteoporosis. If the patient wants to have children but has so far been unsuccessful, his ejaculate will be examined.
A morning testosterone concentration in the blood of 12-35 nmol/l is considered normal. Testosterone treatment might be recommended if this value is found to be below 12 nmol/l. There is general agreement that total testosterone levels above 12 nmol/L (346 ng/dL) or free testosterone levels above 250 pmol/L (72 pg/mL) do not require testosterone treatment. ISSAM, EAU and ISA suggest that serum total testosterone levels below 8 nmol/L (231 ng/dL) or free testosterone below 180 pmol/L (52 pg/mL) require substitution. Since symptoms of testosterone deficiency become manifest between 8 and 12 nmol/L, trials of treatment can be considered in those in whom alternative causes of these symptoms have been excluded.1
In addition, concentrations of the pituitary hormones can be measured. They provide information as to whether the testosterone deficiency is due to disorders of testicular function or of the hypothalamic-pituitary system.
References:
1. Nieschlag E, Swerdloff R, Behre HM, Gooren L, Kaufman JM, Legros JJ, Lunenfeld B, Morley J, Schulman C, Wang C, Weidner W, Wu F: Investigation, Treatment and Monitoring of Late-Onset Hypogonadism in Males – ISA, ISSAM, and EAU Recommendations. Europ Urol 2005; 48: 1–4.