Testosterone, Free (Direct), Serum With Total Testosterone

Testosterone, Free (Direct), Serum With Total Testosterone

Number
	140103
CPT
	84402; 84403
Synonyms
	Free Testosterone (Direct) and Total, Serum ; Testosterone, Free/Tot/Direct
Test Includes
	Total testosterone
Special Instructions
	State patient's age and sex on the request form.
Specimen
	Serum
Volume
	2 mL
Minimum Volume
	0.7 mL (Note: This volume does not allow for repeat testing.)
Container
	Red-top tube or gel-barrier tube
Collection
	If a red-top tube is used, transfer separated serum to a plastic transport tube.
Storage Instructions
	Refrigerate
Causes for Rejection
	Gross lipemia (may yield erroneously high free testosterone results); plasma specimen; recently administered isotopes
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)
Limitations
	A pediatric reference interval has not been established for the direct free testosterone test.
Methodology
	Free: direct analog/radioimmunoassay (RIA); total: immunochemiluminometric assay (ICMA)
References
	Catrou PG and Beeler MF, “Disorders of Gonadal and Fetoplacal Function,” Interpretations in Clinical Chemistry, 2nd ed, Chicago, IL: America Society of Clinical Pathologists, 1983, 76-82. Green PJ and Yucis MJ, “Free Testosterone Determinations by Ultrafiltration and Comparison With Dialysis,” Clin Chem, 1982, 28(5):1237-8. Ruutiainen K, Sannikka E, Santti R, et al, “Salivary Testosterone in Hirsutism: Correlations With Serum Testosterone and the Degree of Hair Growth,” J Clin Endocrinol Metab, 1987, 64(5):1015-20. Vittek J, L'Hommedieu DG, Gordon GG, et al, “Direct Radioimmunoassay (RIA) of Salivary Testosterone: Correlation With Free and Total Serum Testosterone,” Life Sci, 1985, 37(8):711-6. Vlahos I, MacMahon W, Sgoutas D, et al, “An Improved Ultrafiltration Method for Determining Free Testosterone in Serum,” Clin Chem, 1982, 28(11):2286-91. Wheeler JE and Rudy FR, “The Tests, Paratesticular Structures, and Male External Genitalia,” Principles and Practice of Surgical Pathology, 2nd ed, Volume 2, Silverburg SG, ed. New York, NY: Churchill Livingstone, 1990, 1531-85.