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Test Name:
Testosterone, Total and Free, by ED/LC-MS/MS

• SBMF No:
  42107
• Performance Lab Name:
  Mayo Medical Laboratories
• Test Mnemonic:
  FTEST DIAL
• ABN:
  Required – Not FDA-Approved
• CPT Code:
  84402; 84403
• LOINC Code:
  19146-0
• Ref Lab Test No:
  8508
• Test Includes:
  Testosterone, Free, Equilibrium Dialysis
  Testosterone, Total, Liquid Chromatography-Tandem Mass Spectrometry
• Also See:
  30033 Testosterone, Total, Free, Bioavailable, and SHBG
• Spec Type:
  Serum
• Spec Container:
  Red top (serum) tube
• Pref Vol:
  2.5 mL
• Min Vol:
  2.0 mL
• Fasting:
  No
• Spec Collect:
  Do not use gel-barrier tubes for specimen collection
  Routine venipuncture
• Spec Process:
  Clot 30 minutes
  Promptly centrifuge 15 minutes
  Immediately transfer serum to separate plastic tube
• Spec Store Transport:
  Refrigerated
• Spec Reject:
  Grossly hemolyzed, lipemic, or icteric sample
  Plasma sample
• Spec Remarks:
  Use of gel-barrier tube may cause interference in total testosterone levels
• Methodology:
  Equilibrium Dialysis
  Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
• Use:
  This assay is the alternative, second-level test for suspected increases or decreases in physiologically active testosterone (preferred: #30033 "Testosterone, Total, Free, Bioavailable, and SHBG"); 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
• Clinical Significance:
  

  Testosterone is the major androgenic hormone. It is responsible for the development of the male external genitalia and secondary sexual characteristics. In females, its main role is as an estrogen precursor. In both genders, it also exerts anabolic effects and influences behavior.

  In men, testosterone is secreted by the testicular Leydig cells and, to a minor extent, by the adrenal cortex. In premenopausal women, the ovaries are the main source of testosterone with minor contributions by the adrenals and peripheral tissues. After menopause, ovarian testosterone production is significantly diminished. Testosterone production in testes and ovaries is regulated via pituitary-gonadal feedback involving luteinizing hormone (LH) and, to a lesser degree, inhibins and activins.

  Most circulating testosterone is bound to sex hormone-binding globulin (SHBG), which in men also is called testosterone-binding globulin. A lesser fraction is albumin bound and a small proportion exists as free hormone. Historically, only the free testosterone was thought to be the biologically active component. However, testosterone is weakly bound to serum albumin and dissociates freely in the capillary bed, thereby becoming readily available for tissue uptake. All non-SHBG-bound testosterone is therefore considered bioavailable.

  During childhood, excessive production of testosterone induces premature puberty in boys and masculinization in girls. In adult women, excess testosterone production results in varying degrees of virilization, including hirsutism, acne, oligo-amenorrhea, or infertility. Mild-to-moderate testosterone elevations are usually asymptomatic in males, but can cause distressing symptoms in females. The exact causes for mild-to-moderate elevations in testosterone often remain obscure. Common causes of pronounced elevations of testosterone include genetic conditions (eg, congenital adrenal hyperplasia); adrenal, testicular, and ovarian tumors; and abuse of testosterone or gonadotrophins by athletes.

  Decreased testosterone in females causes subtle symptoms. These may include some decline in libido and nonspecific mood changes. In males, it results in partial or complete degrees of hypogonadism. This is characterized by changes in male secondary sexual characteristics and reproductive function. The cause is either primary or secondary/tertiary (pituitary/hypothalamic) testicular failure. In adult men, there also is a gradual modest, but progressive, decline in testosterone production starting between the 4th and 6th decades of life. Since this is associated with a simultaneous increase of SHBG levels, bioavailable testosterone may decline more significantly than apparent total testosterone, causing nonspecific symptoms similar to those observed in testosterone deficient females. However, severe hypogonadism, consequent to aging alone, is rare.

  Measurement of total testosterone (#30101 "Testosterone, Total") is often sufficient for diagnosis, particularly if it is combined with measurements of LH and follicle-stimulating hormone (FSH) (#30096 "Luteinizing Hormone [LH], Serum" and #30093 "Follicle-Stimulating Hormone [FSH], Serum"). However, these tests may be insufficient for diagnosis of mild abnormalities of testosterone homeostasis, particularly if abnormalities in SHBG (#30032 "Sex Hormone Binding Globulin [SHBG]") function or levels are present. Additional measurements of free testosterone or bioavailable testosterone are recommended in this situation; bioavailable (#30033 "Testosterone, Total, Free, Bioavailable, and SHBG") is the preferred assay.

• Reference Range:
  

  Testosterone, Free
  Males: 9-30 ng/dL
  Females: 0.3-1.9 ng/dL
  
  Reference values are not established for subjects <16 years.

  Testosterone, Total

  Age-Adjusted Ranges	Reference Range (ng/dL)
  Males
  0-5 months 6 months-9 years 10-11 years 12-13 years 14 years 15-16 years 17-18 years ≥19 years	75-400 <7-20 <7-130 <7-800 <7-1,200 100-1,200 300-1,200 240-950
  Females
  0-5 months 6 months-9 years 10-11 years 12-16 years 17-18 years ≥19 years	20-80 <7-20 <7-44 <7-75 20-75 8-60
  Tanner Stages*	Reference Range (ng/dL)
  Males
  I (prepubertal) II III IV V (young adult)	<7-20 8-66 26-800 85-1,200 300-950
  Females
  I (prepubertal) II III IV V (young adult)	<7-20 <7-47 17-75 20-75 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.

• Additional Test Info:
  This test was developed and its performance characteristics determined by Laboratory Medicine and Pathology, Mayo Clinic. This test has not been cleared or approved by the U.S. Food and Drug Administration.
• Day Run:
  Mon-Fri, Sun
• Time Reported:
  4-6 days
• Test Type:
  HORMONE