Testosterone, LC/MS/MS |
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Test Summary |
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See also Test Application and Interpretation section of The Quest Diagnostics Manual: Endocrinology Test Selection and Interpretation.
Clinical Use
| • | Diagnose and monitor hyperandrogenic disorders such as polycystic ovary syndrome in women with alopecia, acne, and hirsutism |
| • | Diagnose and monitor therapy in patients with androgen secreting neoplasms and congenital or non-classical (late-onset) adrenal hyperplasia |
| • | Determine androgen status in children with precocious or delayed puberty, ambiguous genitalia, or unexplained virilization |
| • | Diagnose testosterone deficiency in men |
| • | Monitor prostate cancer therapies (gonadotropin-releasing hormone analogs and antiandrogens) |
Clinical Background
Testosterone is produced by the testicular Leydig cells in males and by the adrenal glands (25%), ovaries (25%), and peripheral conversion of circulating androstenedione (50%) in females.1 In both males and females, the majority of circulating testosterone is protein bound. Sex hormone binding globulin (SHBG), the major binding protein, binds 60% to 70% of the testosterone in circulation. The remaining testosterone circulates weakly bound to other proteins, primarily albumin, and as free (not bound to protein) testosterone. Albumin-bound testosterone accounts for 30% to 40% of the testosterone in circulation, and free, approximately 2%.
Testosterone bound to SHBG is biologically inactive because of the strong affinity between SHBG and testosterone. Free testosterone is biologically active, as is albumin bound (due to weak albumin-testosterone binding). Albumin-bound and free testosterone, together, are frequently referred to as the biologically active or bioavailable fraction. In most situations, the bioavailable fraction increases as total testosterone increases or as SHBG decreases.
In utero, testosterone is necessary for the development of male genitalia in 46,XY fetuses.2 After birth, the serum concentration in boys remains approximately twice that of girls until puberty. In boys, a more than 10-fold increase during puberty leads to the development of secondary sexual characteristics, whereas in girls, a 2-fold increase leads to the development of pubic and axillary hair.3 In women, serum testosterone concentration is approximately 5%-10% of that in men and is thought to be important in the maintenance of bone mineral density, mood, and libido.1,4 In men, testosterone is necessary for the maintenance of spermatogenesis, secondary sexual characteristics, bone density, muscle mass, and libido and is thought to play a role in memory recall.5
Recent evidence suggests traditional immunoassays are unable to accurately quantitate the low serum testosterone concentrations found in women and children,6,7 in men with androgen deficiencies,8 and in patients undergoing antiandrogenic therapies.8 Liquid chromatography tandem mass spectrometry (LC/MS/MS) has recently emerged as the method of choice for measuring testosterone in these populations because of markedly increased sensitivity and specificity.6,8 Additionally, turbulent flow LC/MS/MS, as used in this assay, requires lower sample volume and provides greater sensitivity than liquid/liquid or derivatization LC/MS/MS.9
Individuals Suitable for Testing
| • | Women and children with suspected androgen excess |
| • | Newborns with ambiguous genitalia |
| • | Children with evidence of precocious or delayed puberty |
| • | Men with suspected testosterone deficiency |
| • | Men with prostate cancer treated with gonadotropin-releasing hormone analogs and antiandrogen therapies |
Specimen Requirements
| • | Refrigerated serum (no-additive red-top tube) is preferred. Heparinized plasma (green-top tube) is acceptable. Serum collected in serum separator tubes (SST) is unacceptable. |
| • | Total Testosterone (Women and Children): 1 mL; 0.18 mL minimum. |
| • | Free and Total Testosterone: 1 mL; 0.5 mL minimum. |
| • | Free, Bioavailable, and Total Testosterone: 2.5 mL; 1.1 mL minimum. |
Method
| • | Total Testosterone (Women and Children) | |
| – | Turbulent flow liquid chromatography tandem mass spectrometry (LC/MS/MS) | |
| – | Analytical sensitivity: 1.0 ng/dL | |
| – | Analytical specificity: no cross-reactivity with 30 testosterone-related steroid compounds Reportable range: 1.0 to 2000 ng/dL | |
| – | CPT Code:* 84403 | |
| • | Free and Total Testosterone | |
| – | Total: LC/MS/MS | |
| – | Percent free: equilibrium dialysis | |
| – | Free: calculated based on total and percent free | |
| – | Aliases: testosterone index, dialyzable testosterone | |
| – | CPT Codes:* 84403, 84402 | |
| • | Free, Bioavailable, and Total Testosterone | |
| – | Total: LC/MS/MS | |
| – | Free: calculated based on constants for the binding of testosterone to SHBG and albumin | |
| – | Bioavailable: calculated based on constants for the binding of testosterone to SHBG and albumin | |
| – | SHBG: extraction, chromatography, radioimmunoassay | |
| – | Albumin: spectrophotometry | |
| – | Aliases: free, weakly bound, and total testosterone | |
| – | CPT Codes:* 84403, 84270, 82040 | |
Reference Range
See Tables 1, 2, and 3.
Interpretive Information
Testosterone is elevated in infants with congenital adrenal hyperplasia secondary to 21-hydroxylase or 11-hydroxylase deficiencies, conditions that cause masculinization of the genitalia in female fetuses.2,12 Serum testosterone concentrations may also be increased or decreased in other disorders associated with ambiguous genitalia in newborns (Table 4).12,13 In adolescent children, elevated testosterone may be diagnostic of precocious puberty, whereas a decreased concentration may be indicative of hypogonadism in boys.3
In women, elevated serum testosterone commonly manifests as alopecia, severe acne, hirsutism, and/or menstrual disturbances. Elevations can result from androgen-secreting tumors of the adrenal gland or ovary, polycystic ovary syndrome, late onset congenital adrenal hyperplasia, or Cushing’s syndrome.14
In men, decreased testosterone levels may be due to primary testicular failure (associated with elevated LH and FSH) or secondary hypogonadism (associated with decreased LH and FSH), or treatment of prostate cancer with gonadotropin releasing hormone analogs or antiandrogens.15 Elevated testosterone levels may result from androgen-secreting tumors of the adrenal gland, late onset congenital adrenal hyperplasia, or Cushing's syndrome.5
Medical conditions altering serum concentrations of SHBG or albumin (eg, obesity or cirrhosis) may affect the total testosterone level, though free and bioavailable testosterone may remain normal. Additionally, certain hirsute females may have a normal total testosterone level while their free and bioavailable testosterone are elevated. Testosterone results should be interpreted in conjunction with other laboratory and clinical findings.
Online Resources for Healthcare Professionals
| • | Obtain test ordering codes and specimen requirements from our online Test Menu. |
| • | Visit our Test Selection and Interpretation Guide for information relating to endocrinology test selection, utilization, and interpretation. |
| • | Simplify test ordering and results reporting with Care360™. |
| • | Learn about Quest Diagnostics Nichols Institute section of our Web site. |
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References
1 Burger H. Androgen production in women. Fertility and Sterility. 2002;77(Suppl 4):3-5.
2 American Academy of Pediatrics: Evaluation of the newborn with developmental anomalies of the external genitalia. Pediatrics. 2000;106:138-142.
3 Grumbach M, Styne D. Puberty: Ontogeny, neuroendocrinology, physiology, and disorders. In: Wilson, Foster, Kronenberg, et al. eds. Williams Textbook of Endocrinology. 9th ed. Philadephia, PA: W.B. Saunders Company; 1998:1550-1625.
4 Snyder P. Editorial: The role of androgens in women. J Clin Endocrinol Metab. 2001;86:1006-1007.
5 Griffin JE, Wilson JD. Disorders of the testes and the male reproductive tract. In: Wilson, Foster, Kronenberg, et al. eds. Williams Textbook of Endocrinology. 9th ed. Philadephia, PA: W.B. Saunders Company; 1998:819-875.
6 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.
7 Herold D, Fitzgerald R. Immunoassays for testosterone in women: better than guessing? Clin Chem. 2003;49:1250-1251.
8 Wang C, Catlin DH, Demers LM, et al. Measurement of total serum testosterone in adult men: comparison of current laboratory methods versus liquid chromatography-tandem mass spectrometry. J Clin Endocrinol Metab. 2004;89:534-543.
9 Grant RP, Cameron C, Mackenzie-McMurter S. Generic serial and parallel on-line direct-injection using turbulent flow liquid chromatography/tandem mass spectrometry. Rapid Commun Mass Spectrom. 2002;16:1785-1792.
10 Forest MG, Sizonenko PS, Cathiard AM, et al. Hypophyso-gonadal function in humans during the first year of life: I. Evidence for testicular activity in early infancy. J Clin Invest. 1974;53:819-828.
11 Forest MG, Cathiard AM, Bertrand JA. Total and unbound testosterone levels in the newborn and in normal and hypogonadal children: use of a sensitive radioimmunoassay for testosterone. J Clin Endocrinol Metab. 1973;36:1132-1142.
12 Nelson C, Gearhart J. Current views on evaluation, management, and gender assignment of the intersex infant. Nature Clinical Practice Urology. 2004;1:38-43.
13 Hershlag A, Peterson C. Endocrine Disorders. In: Berek J, Adashi E, Hillard P, et al. eds. Novak's Gynecology. 12th ed. Baltimore, MA: Williams and Wilkins; 1996:833-886.
14 Migeon C, Wisniewski A, Gearhart J. Syndromes of abnormal sex differentiation: a guide for patients and their families [Johns Hopkins Hospital, Baltimore, MD Web site]. May, 2001. Available at http://www.hopkinsmedicine.org/pediatricendocrinology/intersex/sexdiff.pdf. Accessed December 28, 2004.
15 Leibowitz RL, Tucker SJ. Treatment of localized prostate cancer with intermittent triple androgen blockage: preliminary results in 110 consecutive patients. Oncologist. 2001;6:177-182.
* The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed.
This test was developed and its performance characteristics determined by Quest Diagnostics Nichols Institute. It has not been cleared or approved by the U.S. Food and Drug Administration. The FDA has determined that such clearance or approval is not necessary. Performance characteristics refer to the analytical performance of the test.
