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Test Code TSTO or LAB124 Total Testosterone, Serum or Plasma

Important Note

The suggested collection time is in the morning, preferably before 10 am. Or within 3 hours of waking. Testing should occur when the sleep-wake pattern is stable (i.e., not during shift changes or jet lag). Do not test during acute illness or hospitalization.

For additional information, please see the Practical Testosterone Testing for Men article.

Specimen Requirements

Container Type:

Optimal: Gold or Mint*

*For STAT requests

Acceptable: Red or Green
Optimal Collection Volume: 

4.5mL; full tube
Minimum Volume:

1 mL whole blood
Collection Instructions:

Gently invert the sample 5-6 times after collection.
Specimen Transport:

Refrigerate
Processing Instructions: 

1. If serum, allow the specimen to clot for 30 minutes.

2. Centrifuge specimen within 2 hours of collection.

3. After centrifugation, specimen tubes without a gel barrier should have the serum or plasma aliquoted to a false bottom container.

4. Keep serum or plasma refrigerated until testing can be performed.

Specimen Stability

Specimen Type Temperature Time
Serum* Refrigerated 14 days
Room Temperature 5 days
Frozen 6 months

*Note: Heparinized plasma in gel separator tubes is less stable than serum and only suitable for add-on testing up to 2 days after sample collection.

Specimen Rejection Criteria

Hemolysis Mild OK; Moderate OK; Gross Reject
Lipemia Mild OK; Moderate OK; Gross Reject
Icterus Mild OK; Moderate OK; Gross Reject
Other Quantity not sufficient

Useful For

Men

  • Evaluating men with symptoms or signs of possible hypogonadism, such as loss of libido, erectile dysfunction, gynecomastia, osteoporosis, or infertility
  • Evaluating boys with delayed or precocious puberty
  • Monitoring testosterone replacement therapy
  • Monitoring antiandrogen therapy (eg, used in prostate cancer, precocious puberty, treatment of idiopathic hirsutism, male-to-female transgender disorders, etc.)

 

Women

  • Evaluating women with hirsutism, virilization, and oligoamenorrhea
  • Evaluating women with symptoms or signs of possible testosterone deficiency
  • Evaluating infants with ambiguous genitalia or virilization
  • Diagnosing androgen-secreting tumors

Methodology

Roche Cobas - Electrochemiluminescence assay

Reference Ranges

Male, adult

Age group Reference Range and Reporting Units
18-49 years 249-836 ng/dL
> 50 years 193-740 ng/dL

 

Female, adult

Age group Reference Range and Reporting Units
18-49 years 8.4-48.1 ng/dL
> 50 years 2.9-40.8 ng/dL

 

Note: The reference ranges below for children are based on the Tanner Stage model

 

Male, child

Tanner Stage Min (ng/dL) Max (ng/dL)
1 < 2.5 < 2.5
2 < 2.5 432
3 64.9 778
4 180 763
5 188 882

 

Female, child

Tanner Stage Min (ng/dL) Max (ng/dL)
1 < 2.5 6.1
2 < 2.5 10.4
3 < 2.5 23.7
4 < 2.5 26.8
5 4.6 38.3

 

Interpretive

Men - Helpful in diagnosing hypogonadism, estrogen therapy, chromosome aberrations, and liver cirrhosis) when a reduction in testosterone production is suspected

 

Women - helpful in diagnosing androgenic syndrome (AGS), polycystic ovaries, and when an ovarian tumor, adrenal tumor, adrenal hyperplasia, or ovarian insufficiency is suspected. 

Day(s) Performed

24/7

Expected TAT

Same day

Performing Laboratory

Bronson Laboratory, Chemistry - Kalamazoo

Sample Retention Time

7 days

CPT Code

84403

LOINC Code

2986-8