Testosterone
Code:
TEST
Sample Type:
Serum (Gold Top)
Minimum volume: 1 mL
Ref Ranges/Units:
Adult:
Male – age related ranges:
20-49 years 8.6 – 29.0 nmol/L
>50 years 6.7 – 25.7 nmol/L
Female – age related ranges:
20-49 years 0.3 – 1.7 nmol/L
>50 years 0.1 -1.4 nmol/L
Turnaround:
Immunoassay – Same Day.
LCMS – within 1-2 weeks.
Stability:
5 days at 20‑25°C
14 days at 2‑8°C
6 months at ‑20°C
Freeze only once
Special Precautions/Comments:
9am testosterone sample is recommended due to diurnal variation.
Additional Information:
Testosterone is an androgen which is responsible for male sex characteristics. In males, it is produced by the Leydig cells of the testes in response to luteinizing hormone (LH) secretion from the pituitary. In females, testosterone is produced in small amounts in the ovary, adrenal glands and in the periphery via conversion of androstenedione.
Measurement of total testosterone is used in the investigation of libido and erectile dysfunction in men. It is also measured in the investigation for hirsutism, amenorrhoea and polycystic ovarian syndrome (PCOS) in women. Testosterone may be significantly raised in virilizing tumours.
Male testosterone levels are assessed by immunoassay. Female testosterone levels are measured by immunoassay in the first instance and then by a more sensitive method (liquid chromatography tandem mass spectrometry) if indicated.
Measurement of sex hormone binding globulin (SHBG) can be useful to calculate the free testosterone, known as the free androgen index (FAI). Measurement of LH can also help aid the interpretation of testosterone in hypogonadal males.
Free androgen index (FAI) = 100*(total testosterone/SHBG)
South of Tyne & Wear Pathology Centre
