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Testosterone, Free, Equilibrium Ultrafiltration With Total Testosterone

CPT: 84402; 84403
Updated on 07/31/2020
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Test Includes

Total, free, and percent free testosterone


Special Instructions

State patient's age and sex on the test request form.


Expected Turnaround Time

2 - 4 days




Specimen Requirements


Specimen

Serum


Volume

2.50 mL


Minimum Volume

1 mL (Note: This volume does not allow for repeat testing.)


Container

Red-top tube or gel-barrier tube


Collection

Separate serum from cells. If a red-top tube is used, transfer separated serum to a plastic transport tube.


Storage Instructions

Refrigerate


Stability Requirements

Temperature

Period

Room temperature

14 days

Refrigerated

14 days

Frozen

14 days

Freeze/thaw cycles

Stable x3


Causes for Rejection

Gross lipemia; recently administered isotopes; plasma specimen


Test Details


Use

Evaluate hirsutism and masculinization in women; evaluate testicular function in clinical states where the testosterone binding proteins may be altered (obesity, cirrhosis, thyroid disorders)


Methodology

Free: equilibrium ultrafiltration; total: electrochemiluminescence immunoassay (ECLIA)


Reference Interval

See table.1

Free Testosterone

Age

Male (ng/dL)

Female (ng/dL)

Cord blood

0.50−2.20

0.40−1.60

1 to 15 d

0.15−3.10

0.05−0.25

1 to 2 m

0.33−0.80

0.01−0.13

3 to 5 m

0.07−1.40

0.03−0.11

6 to 7 m

0.04−0.48

0.02−0.06

6 to 9 y

0.01−0.32

0.01−0.09

10 to 11 y

0.06−0.57

0.10−0.52

12 to 14 y

0.14−15.60

0.10−0.52

15 to 17 y

8.00−15.90

0.10−0.52

Adults

5.00−21.00

0.10−0.85

Percentage of Total Testosterone

Age

Male (%)

Female (%)

Cord blood

2.00−4.40

2.00−3.90

1 to 15 d

0.90−1.70

0.80−1.50

1 to 2 m

0.40−0.80

0.40−1.10

3 to 5 m

0.40−1.10

0.50−1.00

6 to 7 m

0.40−1.00

0.50−0.80

6 to 9 y

0.90−1.70

0.90−1.40

10 to 11 y

1.00−1.90

1.00−1.90

12 to 14 y

1.30−3.00

1.00−1.90

15 to 17 y

1.80−2.70

1.00−1.90

Adults

1.50−4.20

0.50−2.80

See table.1

Age

Male (ng/dL)

Female (ng/dL)

Free Testosterone

Cord blood

0.50−2.20

0.40−1.60

1 to 15 d

0.15−3.10

0.05−0.25

1 to 2 m

0.33−0.80

0.01−0.13

3 to 5 m

0.07−1.40

0.03−0.11

6 to 7 m

0.04−0.48

0.02−0.06

6 to 9 y

0.01−0.32

0.01−0.09

10 to 11 y

0.06−0.57

0.10−0.52

12 to 14 y

0.14−15.60

0.10−0.52

15 to 17 y

8.00−15.90

0.10−0.52

Adults

5.00−21.00

0.10−0.85

Percentage of Total Testosterone

Cord blood

2.00−4.40

2.00−3.90

1 to 15 d

0.90−1.70

0.80−1.50

1 to 2 m

0.40−0.80

0.40−1.10

3 to 5 m

0.40−1.10

0.50−1.00

6 to 7 m

0.40−1.00

0.50−0.80

6 to 9 y

0.90−1.70

0.90−1.40

10 to 11 y

1.00−1.90

1.00−1.90

12 to 14 y

1.30−3.00

1.00−1.90

15 to 17 y

1.80−2.70

1.00−1.90

Adults

1.50−4.20

0.50−2.80

See table.1

Free Testosterone

Age

Male (ng/dL)

Female (ng/dL)

Cord blood

0.50−2.20

0.40−1.60

1 to 15 d

0.15−3.10

0.05−0.25

1 to 2 m

0.33−0.80

0.01−0.13

3 to 5 m

0.07−1.40

0.03−0.11

6 to 7 m

0.04−0.48

0.02−0.06

6 to 9 y

0.01−0.32

0.01−0.09

10 to 11 y

0.06−0.57

0.10−0.52

12 to 14 y

0.14−15.60

0.10−0.52

15 to 17 y

8.00−15.90

0.10−0.52

Adults

5.00−21.00

0.10−0.85

Percentage of Total Testosterone

Age

Male (%)

Female (%)

Cord blood

2.00−4.40

2.00−3.90

1 to 15 d

0.90−1.70

0.80−1.50

1 to 2 m

0.40−0.80

0.40−1.10

3 to 5 m

0.40−1.10

0.50−1.00

6 to 7 m

0.40−1.00

0.50−0.80

6 to 9 y

0.90−1.70

0.90−1.40

10 to 11 y

1.00−1.90

1.00−1.90

12 to 14 y

1.30−3.00

1.00−1.90

15 to 17 y

1.80−2.70

1.00−1.90

Adults

1.50−4.20

0.50−2.80


Additional Information

The concentration of free testosterone is very low, typically <2% of the total testosterone concentration. In most men and women, >50% of total circulating testosterone is bound to sex hormone-binding globulin (SHBG) and most of the rest is bound to albumin.2 Routinely available assay methods used to measure total testosterone are not sensitive enough to accurately quantitate the free testosterone fraction directly. Free testosterone is estimated in this profile by an indirect method, equilibrium ultrafiltration. Tritiated testosterone is added to the sample and allowed to come to equilibrium with testosterone in the serum at physiological temperature.3,4 The amount of the added radiolabeled testosterone must be low enough to ensure that the addition will not significantly increase the total testosterone concentration. Once equilibrium is achieved, the free testosterone is separated from the bound by filtration through a membrane by centrifugal ultrafiltration.5 The radioactivity of the protein-free ultrafiltrate is measured and used to calculate the percent free testosterone. The concentration of free testosterone is then calculated by multiplying the percent free testosterone by the total testosterone concentration.


Footnotes

1. Tietz NW, ed. Clinical Guide to Laboratory Tests. 3rd ed. Philadelphia, Pa: WB Saunders Co; 1995:578.
2. Wheeler MJ. The determination of bioavailable testosterone. Ann Clin Biochem. 1995; 32(Pt 4):345-357 (review). 7486793
3. Klee GG, Heser DW. Techniques to measure testosterone in the elderly. Mayo Clin Proc. 2000; 75(Suppl):S19-S25. 10959211
4. Gronowski AM, Landau-Levine M. Reproductive endocrine function. In Burtis CA, Ashwood ER, eds. Tietz Textbook of Clinical Chemistry. 3rd ed. Philadelphia, Pa: WB Saunders Co; 1999:1601-1641.
5. Vlahos I, MacMahon W, Sgoutas D. An improved ultrafiltration method for determining free testosterone in serum. Clin Chem. 1982; 28(11):2286-2291.7127776

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
081786 Testosterone, Free/Tot Equilib 004227 Testosterone, Serum ng/dL 2986-8
081786 Testosterone, Free/Tot Equilib 080796 Testosterone,Free ng/dL 2991-8
081786 Testosterone, Free/Tot Equilib 080770 % Free Testosterone % 15432-8

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