Testosterone

General Information

Androgens are a group of steroids which cause masculinisations of the genital tract and the development and maintenance of male secondary sexual characteristics. They also contribute to muscle bulk, bone mass, libido and sexual performance in men. Testosterone is the major androgen secreted by the Leydig cells of the testes, and its production increases during puberty. Women produce about 5% to 10% as much testosterone as men. Testosterone directly effects some aspects of secondary sexual characteristics such as deepening of voice, increase of muscle mass and libido and also has some indirect effects in tissue with high 5alpha-reductase activity, where it serves as a prohormone to formation of dihydrotestosterone.

Testosterone may be requested, together with measurement of FSH and LH, in males for invesigation of sexual dysfunction or infertility.

In the female, testosterone is secreted by the ovary (60%) and is also derived from the peripheral conversion of androstenedione (40%) which is secreted in equal amounts by the ovary and adrenal. Hence, elevated serum testosterone levels can either be of ovarian or adrenal origin. Testosterone may be requested, together with other endocrine investigations, for the investigation of secondary amenorrhea, infertility or hirsutism/virilization. Due to the normally lower ciculating levels of testosterone in females, this automated method does not have the required sensitivity to measure Female Testosterone levels to the required precision and accuracy. Therefore a seperate LC-MS/MS assay is used in the laboratory for female patients.

Patient Preparation

None

Notes

Testosterone in male patients is measured using an automated Alinity immunoassay.

Testosterone in paediatric and female patients is measured using mass spectrometry.

All referral samples, regardless of sex or age, are measured by mass spectrometry.

If mass spectrometry analysis is required outside the above parameters, please contact the Duty Biochemist on ext.16543.