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Test Code FTG Testosterone, Total and Free, Serum

Reporting Name

Testosterone, Total and Free, S

Useful For

This assay is the alternative, second-level test for suspected increases or decreases in physiologically active testosterone (preferred: TTBS / Testosterone, Total and Bioavailable, Serum); indications:

-Assessment of androgen status in cases with suspected or known sex hormone-binding globulin-binding abnormalities

-Assessment of functional circulating testosterone in early pubertal boys and older men

-Assessment of functional circulating testosterone in women with symptoms or signs of hyperandrogenism, but normal total testosterone levels

-Monitoring of testosterone therapy or antiandrogen therapy in older men and in females


Specimen Required


Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Specimen Volume: 2.5 mL

Additional Information: Patient's age and sex are required.


Seattle Children's Hospital Note:

Collect 5.0 mL whole blood in Red Top.

Specimen Type

Serum

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 14 days
  Frozen  60 days

Day(s) and Time(s) Performed

Monday through Friday; 2 p.m. Saturday and Sunday; Varies

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

FRTST: Equilibrium Dialysis

TTST: Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Method Description

Free Testosterone:

This method is based on equilibrium dialysis in which free-labeled testosterone is allowed to pass through a semipermeable membrane, whereas testosterone bound to the sex hormone-binding globulin (SHBG) remains inside the dialysis tubing. After dialysis, radioactivity is measured both inside and outside the tubing; the free testosterone results are expressed as a percentage of total testosterone. The resulting percentage is multiplied by the total testosterone concentration obtained by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and an absolute free testosterone value is obtained.(Vermeulen A, Stoica T, Verdonck L: The apparent free testosterone concentration, an index of androgenicity. J Clin Endocrinol Metab 1971;33:759-767; Bammann BL, Coulam C, Jiang NS: Total and free testosterone during pregnancy. Am J Obstet Gynecol 1980;137:293-298)

 

Total Testosterone:

Deuterated stable isotope (d3-testosterone) is added to a 0.2-mL serum sample as an internal standard. Protein is precipitated from the mixture by the addition of acetonitrile. The testosterone and internal standard are extracted from the resulting supernatant by an online extraction utilizing high-throughput liquid chromatography (HTLC). This is followed by conventional liquid chromatography and analysis on a tandem mass spectrometer equipped with a heated nebulizer ion source.(Wang C, Catlin DH, Demers LM, et al: Measurement of total testosterone in adult men: comparison of current laboratory methods versus liquid chromatography-tandem mass spectrometry. J Clin Endocrinol Metab 2004;89:534-543; Taieb J, Mathian B, Millot F, et al: Testosterone measured by 10 immunoassays and by isotope-dilution gas chromatography-mass spectrometry in sera from 116 men, women, and children. Clin Chem 2003;49:1381-1395)

Reference Values

TESTOSTERONE, FREE

Males (adult):

20 - <25 years: 5.25-20.7 ng/dL

25 - <30 years: 5.05-19.8 ng/dL

30 - <35 years: 4.85-19.0 ng/dL

35 - <40 years: 4.65-18.1 ng/dL

40 - <45 years: 4.46-17.1 ng/dL

45 - <50 years: 4.26-16.4 ng/dL

50 - <55 years: 4.06-15.6 ng/dL

55 - <60 years: 3.87-14.7 ng/dL

60 - <65 years: 3.67-13.9 ng/dL

65 - <70 years: 3.47-13.0 ng/dL

70 - <75 years: 3.28-12.2 ng/dL

75 - <80 years: 3.08-11.3 ng/dL

80 - <85 years: 2.88-10.5 ng/dL

85 - <90 years: 2.69-9.61 ng/dL

90 - <95 years: 2.49-8.76 ng/dL

95-100+ years: 2.29-7.91 ng/dL

 

Males (children):

<1 year: Term infants

 

1 to 15 days: 0.20-3.10 ng/dL*

16 days to 1 year: Values decrease gradually from newborn (0.20-3.10 ng/dL) to prepubertal levels

*Citation: J Clin Endocrinol Metab 1973;36(6):1132-1142

 

1-8 years: <0.04-0.11 ng/dL

9 years: <0.04-0.45 ng/dL

10 years: <0.04-1.26 ng/dL

11 years: <0.04-5.52 ng/dL

12 years: <0.04-9.28 ng/dL

13 years: <0.04-12.6 ng/dL

14 years: 0.48-15.3 ng/dL

15 years: 1.62-17.7 ng/dL

16 years: 2.93-19.5 ng/dL

17 years: 4.28-20.9 ng/dL

18 years: 5.40-21.8 ng/dL

19 years: 5.36-21.2 ng/dL

 

Females (adult):

20 - <25 years: 0.06-1.08 ng/dL

25 - <30 years: 0.06-1.06 ng/dL

30 - <35 years: 0.06-1.03 ng/dL

35 - <40 years: 0.06-1.00 ng/dL

40 - <45 years: 0.06-0.98 ng/dL

45 - <50 years: 0.06-0.95 ng/dL

50 - <55 years: 0.06-0.92 ng/dL

55 - <60 years: 0.06-0.90 ng/dL

60 - <65 years: 0.06-0.87 ng/dL

65 - <70 years: 0.06-0.84 ng/dL

70 - <75 years: 0.06-0.82 ng/dL

75 - <80 years: 0.06-0.79 ng/dL

80 - <85 years: 0.06-0.76 ng/dL

85 - <90 years: 0.06-0.73 ng/dL

90 - <95 years: 0.06-0.71 ng/dL

95-100+ years: 0.06-0.68 ng/dL

 

Females (children):

<1 year: Term infants

 

1 to 15 days: 0.06-0.25 ng/dL*

16 days to 1 year: Values decrease gradually from newborn (0.06-0.25 ng/dL) to prepubertal levels

*Citation: J Clin Endocrinol Metab, 36(6):1132-1142, 1973

 

1-4 years: <0.04 ng/dL

5 years: <0.04-0.07 ng/dL

6 years: <0.04-0.14 ng/dL

7 years: <0.04-0.23 ng/dL

8 years: <0.04-0.34 ng/dL

9 years: <0.04-0.46 ng/dL

10 years: <0.04-0.59 ng/dL

11 years: <0.04-0.72 ng/dL

12 years: <0.04-0.84 ng/dL

13 years: <0.04-0.96 ng/dL

14 years: <0.04-1.06 ng/dL

15-18 years: <0.04-1.09 ng/dL

19 years: 0.06-1.08 ng/dL

 

TESTOSTERONE, TOTAL

Males        

0-5 months: 75-400 ng/dL

6 months-9 years: <7-20 ng/dL

10-11 years: <7-130 ng/dL

12-13 years: <7-800 ng/dL

14 years: <7-1,200 ng/dL

15-16 years: 100-1,200 ng/dL

17-18 years: 300-1,200 ng/dL

≥19 years: 240-950 ng/dL      

Tanner Stages* 

I (prepubertal): <7-20

II: 8-66

III: 26-800

IV: 85-1,200      

V (young adult): 300-950

 

Females           

0-5 months: 20-80 ng/dL

6 months-9 years: <7-20 ng/dL

10-11 years: <7-44 ng/dL

12-16 years: <7-75 ng/dL

17-18 years: 20-75 ng/dL

≥19 years: 8-60 ng/dL

Tanner Stages*

I (prepubertal): <7-20

II: <7-47

III: 17-75

IV: 20-75

V (young adult): 12-60

 

*Puberty onset (transition from Tanner stage I to Tanner stage II) occurs for boys at a median age of 11.5 (±2) years and for girls at a median age of 10.5 (±2) years. There is evidence that it may occur up to 1 year earlier in obese girls and in African American girls. For boys, there is no definite proven relationship between puberty onset and body weight or ethnic origin. Progression through Tanner stages is variable. Tanner stage V (young adult) should be reached by age 18.

CPT Code Information

84402-Testosterone, free

84403-Total     

LOINC Code Information

Test ID Test Order Name Order LOINC Value
TGRP Testosterone, Total and Free, S 58952-3

 

Result ID Test Result Name Result LOINC Value
3631 Testosterone, Free, S 2991-8
8533 Testosterone, Total, S 2986-8

Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross OK

Icterus

Mild OK; Gross OK

Other

NA

Profile Information

Test ID Reporting Name Available Separately Always Performed
FRTST Testosterone, Free, S No Yes
TTST Testosterone, Total, S Yes Yes

Forms

If not ordering electronically, complete, print, and send a General Request Form (T239) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/general-request-form.pdf).