Laboratory: Clinical Biochemistry  (AUTOMATED)
Test Name:
TESTOSTERONE - (P)
Test Code: TST
Clinical Information:
Test Indications: Testosterone levels are used for the assessment of individuals with clinical symptoms suggestive of androgen deficiency or excess. This includes:
Evaluation of infants with ambiguous genitalia or virilization
Evaluation of boys with delayed or precocius puberty
Monitoring of testosterone replacement or antiandrogen therapy
Women with infertility, hirsutism, virilization or oligomenorrhea
Diagnosis of androgen-secreting tumors
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
In rare cases, substances that alter the measurable concentration of the analyte in the sample or alter antibody binding in the assay may be present in serum. These can result in assay interference due to interraction with one or more reagent antibodies or components and cause falsely elevated or falsely decreased test results. These include structurally similar compounds that cross react with the antibody, heterophile antibodies, human anti-animal antibodies, autoanalyte antibodies, rheumatoid factors and other proteins. Clin Biochem Rev May 2004, 25: 105 - 120
Contact the on-call clinical biochemist if test results are inconsistent wth the clinical picture.

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 occassions 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. J. Clin Endocrinol Metab June 2010, 95 (6): 2536 - 2559

Patient Preparation Instructions: Multivitamins (45–125 µg biotin) or biotin-only supplements up to 1 mg per day do not interfere with this test. Samples should not be taken from patients receiving therapy with high biotin doses (i.e. >5 mg/day) until at least 8 hours after the last dose.
Collection Devices:
Morning (0700 – 1000h) fasting samples, collected on two or more occasions to minimize biological variability, are recommended for the assessment of male hypogonadism.
Specimen Required:


Plasma: 2.0 mL
Pediatric Plasma: 0.3 mL

Stability 14 days refrigerated, 6 months frozen
Referral:
Serum: 2.0 mL

Samples must be transferred to an aliquot tube and stored frozen if analysis will not be complete within 48 hours (#110-10-05 Serum / Plasma Separation Procedure & Transport)
Requisition:
Reference Values:
Female:
    0 - 4 wk:       0.7-2.2 nmol/L
    5 wk - 12 y:    <1 
    ≥ 13 y:          0.5-2.4 

Male:
    0 - 7 mo:      2.6-14    
    8 mo - 12 y:   <1
    ≥ 13 y:           9.7-38                   (nmol/L x 28.8 = ng/dL)
Availability:
Daily
See Also:
More Information:


Albumin will automatically be added to all Testosterone requests in male older than 17 years. if Testosterone is an add-on, please ensure albumin is manually added as well.If Bioavailable Testosterone requested, it may be substituted with FAI (TST and SHBG)