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testosterone in serum

Testosterone in Serum or Plasma (see [3] for comparison of methods) Indications: - evaluation of hypogaonadism in males - levels < 150 ng/dL or > 350 ng/dL identify or exclude biochemical hypogonadism reasonably accurately - *when levels fall between these thresholds, consider serum free testosterone [6] - evaluation of virilization in women Contraindications: - normal testes, no gynecomastia, & regular morning erections [9] Reference values: - testosterone levels in men vary diurnally - highest levels in the morning [7] - diurnal variation declines with ages - in young men, mean levels are - 600 ng/dL at 7 am - 500 ng/dL at 10 am - 400-450 ng/dL at 2 pm [7] - after age 45, mean testosterone levels do not differ between 7 AM to 2 PM [7] - 8 AM serum testosterone levels vary with the season [12] - serum testosterone is lowest in spring & summer & higher in fall & winter - lowest mean level is in May (440 mg/dL) & highest in January (600 ng/dL) [12] - Male: 270-1070 ng/dL - Female: 60- 86 ng/dL - Pre-Pubertal - Female: 0-30 ng/dL - Male: 1-120 ng/dL - reference intervals reported by different laboratories differ - lower limits range from 160-300 ng/dL - upper limits range from 726-1130 ng/dL [10] Clinical significance: In the male, testosterone is mainly synthesized in the interstitial Leydig cells & the testis, & is regulated by the interstitial cell stimulating hormone (ICSH), or luteinizing hormone (LH) of the anterior pituitary (the female equivalent of ICSH). The pulsatile nature of LH secretions results in pulsatile secretions of testosterone. Testosterone is responsible for the development of secondary sex characteristics, such as the accessory sex organs, the prostate, seminal vesicles & growth offacial, pubic & axillary hair. Testosterone measurements have been very helpful in evaluating hypogonadal states. In the female, testosterone levels are normally found to be much lower than those encountered in the normal male. Testosterone in the female comes from 3 sources. It is secreted in small quantities by both the adrenal glands & the ovaries, & in normal women 50-60% of the daily testosterone production arises from peripheral metabolism of prehormones chiefly androstenedione. Virilization in women is associated with the administration of androgens. There appears to be a correlation between serum testosterone levels & the degree of virilization in women, although approximately 25% of women with varying degrees of virilism have serum testosterone levels that fall within the normal female range. Decreases: males 1) hypogonadism 2) orchidectomy 3) pharmaceuticals a) estrogen therapy b) opioids c) high-dose glucocorticoids 4) Klinefelter's syndrome 5) hypopituitarism 6) testicular feminization 7) hepatic cirrhosis 8) andropause* 9) levels drop in men with children * 40% of men > 45 years of age [4] Increases: females: - polycystic ovary syndrome (female) Principle: The Coat-A-Count procedure is a solid-phase radioimmunoassay, wherein I-125 labeled Testosterone competes for a fixed time with Testosterone in the patient sample for sites on Testosterone- specific antibody. This reaction takes place in the presence of blocking agents which serve to liberate bound Testosterone from free. The antibody being immobilized to the wall of a poly- propylene tube decanting the supernatant suffices to terminate the competition & to isolate the antibody-bound fraction of the radiolabeled Testosterone. Counting the tube in the gamma counter then yields a number, which converts by way of a calibration curve to a measure of the Testosterone present in the patient sample. Specimen: 1) Serum or heparinized or EDTA plasma may be used. When serial samples are being evaluated, the same type of specimen should be used throughout the study. 2) If assay is performed within 24 hours after collection, the specimen should be stored in the refrigerator at 2-8*C. If the testing will be delayed more than 24 hours, the specimen should be frozen. Mix thoroughly after thawing to ensure consistency in the results. Avoid repeated freezing & thawing. 3) Specimens showing particulate matter, erythrocytes, or turbidity should be centrifuged before testing. SAMPLE VOLUME: 100 uL of specimen is the minimum volume required to perform the assay.

Related

androgen excess (hyperandrogenism) androgen insufficiency (hypoandrogenism, testosterone deficiency) bioavailable testosterone free testosterone testosterone (Delatestryl Testopel, Striant, Intrinsa, Xyosted)

Specific

testosterone.bound in serum/plasma

General

testosterone in body fluid

References

  1. Diagnostic Products Corporation, 5700 West 96th Street, CA 90045, January 6, 1988.
  2. Henry, John Bernard., Evaluation of Endocrine Function, Clinical Diagnosis & Management, W.B. Saunder Co., Philadelphia, 1984, pp. 305-312
  3. Wang C et al, J Clin Endocrinol Metab 89:534, 2004 PMID: 14764758
  4. Internal Medicine News, July 2005, pg 1,22
  5. Gray, P cited in Netscape Dec 22, 2005
  6. Anawalt BD et al. Performance of total testosterone measurement to predict free testosterone for the biochemical evaluation of male hypogonadism. J Urol 2012 Apr; 187:1369. PMID: 22341266
  7. Welliver RC Jr et al. Validity of midday total testosterone levels in older men with erectile dysfunction. J Urol 2014 Jul; 192:165 PMID: 24518771 http://www.jurology.com/article/S0022-5347%2814%2900115-3/abstract
  8. ARUP - Panel of 5 tests Laboratory Test Directory ARUP: 70102 - Panel of 4 tests Laboratory Test Directory ARUP: 70109 - Panel of 3 tests Laboratory Test Directory ARUP: 70111 - Testosterone, Adult Male Laboratory Test Directory ARUP: 70130 - Panel of 3 tests Laboratory Test Directory ARUP: 81056 - Panel of 3 tests Laboratory Test Directory ARUP: 81057 - Testosterone, LC-MS/MS Laboratory Test Directory ARUP: 81058 - Panel of 5 tests Laboratory Test Directory ARUP: 2001763 - Panel of 3 tests Laboratory Test Directory ARUP: 2002028 - Panel of 3 tests Laboratory Test Directory ARUP: 2002029 - Panel of 4 tests Laboratory Test Directory ARUP: 2002281 - Panel of 5 tests Laboratory Test Directory ARUP: 2002282
  9. Medical Knowledge Self Assessment Program (MKSAP) 16, 17 American College of Physicians, Philadelphia 2012, 2015
  10. Le M, Flores D, May D, Gourley E, Nangia AK. Current practices of measuring and reference range reporting of free and total testosterone in the United States. J Urol 2016 May; 195:1556. PMID: 26707506 http://www.jurology.com/article/S0022-5347%2815%2905446-4/abstract
  11. Shores MM, Matsumoto AM. Testosterone, aging and survival: biomarker or deficiency. Curr Opin Endocrinol Diabetes Obes. 2014 Jun;21(3):209-16. Review. PMID: 24722173 Free PMC Article
  12. Lee JH, Lee SW. Monthly variations in serum testosterone levels: Results from testosterone screening of 8,367 middle-aged men. J Urol 2021 May; 205:1438. PMID: 33350323 https://www.auajournals.org/doi/10.1097/JU.0000000000001546

Component-of

testosterone/cortisol in serum/plasma testosterone/epitestosterone in serum/plasma