Testosterone

Alternative names, keywords

Samples required

● Clotted blood (gold cap, 5 mL tube). Smaller tubes are available for paediatric samples.

Test indications

Test information

Free testosterone is calculated from testosterone and SHBG where requested:

_{Free testosterone = 1000 x (SQR(ZB² + ZC) - ZB)/(2 x ZK)}
_where
_{ZK = [Albumin] x 0.5217 + 1}
_{ZB = [SHBG] - [Total testosterone] + ZK}
_{ZC = 4 x [Total testosterone] x ZK}
_{Source: http://www.issam.ch/freetesuit.htm}

Factors affecting test performance/ results

Total testosterone

male 18 - 49 years	8.64 - 29.0 nmol/L
male ≥ 50 years	6.68 - 25.7 nmol/L
female 18 - 49 years	0.290 - 1.67 nmol/L
female ≥ 50 years	0.101 - 1.42 nmol/L

Paediatric ranges are dependent on pubertal status rather than age. Testosterone (nmol/L, 5th-95th percentiles):

Tanner Stage	Male (7 - 18 years)	Female (8 - 18 years)
1	< 0.09	< 0.21
2	0.09 - 14.99	< 0.36
3	2.25 - 27.0	< 0.82
4	6.25 - 26.5	< 0.93
5	6.53 - 30.6	0.16 - 1.33

_{Source: Roche Cobas® Testosterone II insert, 2023-10, V3.0}

Free testosterone

male 18 - 49 years	198 - 619 pmol/L
male ≥ 50 years	163 - 473 pmol/L
female 18 - 49 years	3 - 33 pmol/L
female ≥ 50 years	1 - 20 pmol/L

_{Source: Roche Cobas^® Testosterone II insert, 2023-10, V3.0}

Reference range

Testosterone esters are metabolized to testosterone; the assay does not differentiate between endogenous testosterone and exogenous testosterone. In general, steroid drugs may interfere.

Nandrolone interferes in this method: do not use samples from patients on Nandrolone treatment.

In isolated cases, elevated testosterone levels can be seen in samples from female patients with end stage renal disease.

Implausible elevated testosterone values in women should be verified by an extraction method or a validated LC.MS/MS tandem method. Please contact Duty Biochemist if this is required.

In rare cases, interference due to extremely high titres of antibodies to analyte-specific antibodies, streptavidin or ruthenium can occur.

Results should always be assessed in conjunction with the patient’s medical history, clinical examination and other findings.

Turnaround time

RSCH same day*, PRH two working days

_{*analysis not available at weekends.}

Enquiries

Biochemistry (Automation)

Test A-Z Index.