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Laboratory: Clinical Biochemistry  (AUTOMATED)
Test Name:
Test Code: TST
Clinical Information:
Test Indications: TTestosterone levels are used for the assessment of individuals with clinical symptoms suggestive of androgen deficiency or excess, such as:

  • Evaluation of infants with ambiguous genitalia or virilization
    Evaluation of boys with delayed or precocious puberty
    Monitoring of testosterone replacement or antiandrogen therapy
    Women with infertility, hirsutism, virilization or oligomenorrhea
    Diagnosis of androgen-secreting tumors

Testosterone by immunoassay may be used to evaluate hypogonadism in males and to monitor testosterone hormone replacement therapies.
Free and bioavailable testosterone may provide additional information when protein-binding abnormalities are suspected: TESTOSTERONE TOTAL, BIOAVAILABLE and FREE (CALCULATED) - (S)
Low testosterone levels found in children, females and individuals on testosterone-suppressing hormone therapy may require follow-up testing by mass spectrometry: TESTOSTERONE, TOTAL & FREE - (S)
If test results are inconsistent with clinical picture, please contact Clinical Biochemist on-duty at 431-276-0131 (9am-4 pm, Monday to Friday excl Stat Holidays).

Recommendations: Endocrine Society Clinical Practice Guidelines recommend making a diagnosis of androgen deficiency only in men with consistent symptoms and unequivocally low serum testosterone levels. Morning (0700 - 1000h) fasting samples, collected on two or more occasions to minimize biological variability, are recommended for the assessment of male hypogonadism. The evaluation of androgen deficiency should not be made during an acute or subacute illness.
Endocrine Society Clinical Practice Guidelines recommend against screening for androgen deficiency in the general population. J. Clin Endocrinol Metab June 2010, 95 (6): 2536 – 2559

Patient preparation instructions: This test is unaffected by multivitamins (45 - 125 µg biotin) or biotin-only supplements (up to 140 ng/mL dose). Fasting is not required, but may be requested (8-12 h) by ordering physician – patients should follow their doctor’s instructions.

Collection Devices:
Acceptable specimen include serum with or without gel and EDTA plasma
Specimen Required:

Plasma: 2.0 mL
Pediatric Plasma: 0.3 mL

Specimen Stability:
Ambient: 5 days
Refrigerated: 7 days
Frozen: 6 months, freeze only once.
Serum: 2.0 mL

Samples must be transferred to an aliquot tube and stored/shipped frozen for all off-site testing (#110-10-05 Serum / Plasma Separation Procedure & Transport)
Reference Values:
 AgeReference Interval
Female0 - <5 wk0.7 – 2.2
5 wk - <13 y< 1.0 
≥13 y0.5 – 2.4
Male0 - <8 mo2.6 – 14
8 mo - <13 y< 1.0
≥13 y9.7 - 38

Additional information:

5-95th percentile
5-95th percentile
Tanner stage 1≤ 0.4 nmol/L≤ 0.4 nmol/L
Tanner stage 2≤ 0.4 nmol/L≤ 15.0 nmol/L
Tanner stage 3≤ 0.8 nmol/L2.3 – 27.0 nmol/L
Tanner stage 4≤ 0.9 nmol/L6.2 – 26.5 nmol/L
Tanner stage 5≤ 1.3 nmol/L6.5 – 30.6 nmol/L
20-49 y≤ 1.7 nmol/L8.6 – 29.0 nmol/L
≥50 y≤ 1.4 nmol/L6.7 – 25.7 nmol/L

Based on 6:30 am – 1:00 pm collection times
Method of Analysis: Roche electrochemiluminescence

See Also:
More Information:
Interpretation & Assay Interferences: Nandrolone (19-nortestosterone) interferes with assay. Samples from patients under Nandrolone treatment should be tested using alternate method.
In isolated cases, elevated testosterone levels can be seen in samples from
female patients with end stage renal disease (ESRD).