Serum free testosterone

Pan G, Hanaoka T, Yoshimura M, Zhang S, Wang P, Tsukino H, Inoue K, Nakazawa H, Tsugane S, Takahashi K (2006) Decreased serum free testosterone in workers exposed to high levels of di-n-butyl phthalate (DBP) and di-2-ethyUiexyl phthalate (DEFIP) a cross-sectional study in China. Environ Health Perspect 114 1643-1648... 

Only a small fraction (1% to 2%) of imconjugated testosterone exists fireely (non-protein bound) in serum or plasma. None of the conventional assay methods, including RIA, is sufficiently sensitive to quantify the free steroid directly in a protein-free ultrafiltrate of plasma. Instead, the free steroid is estimated in plasma by adding a known amount of radiolabeled compound to the sample and allowing labeled and unlabeled compounds to reach equilibrium in their competition for the same binding sites on the proteins. Bound and free radiolabeled fractions are then separated and the ratio of free labeled to total labeled compound is determined. At equilibrium, this ratio is taken as a measure of the free testosterone fraction. An estimate of serum free testosterone can then be calculated by multiplying the free testosterone fraction by the total testosterone concentration. 

Ayurvedic formulations which contain C. forskohlii as one of the ingredients, standardized extracts of C. forskohlii have been marketed in the recent days as nutraceutical supplements mainly for weight loss. Several analytical methods were developed for the quantitation of forskolin in crude extracts as well as in formulations. There is one clinical study in obese men indicating the efficacy of forskolin in inducing weight loss, promoting lean body mass, bone mass, and increasing serum free testosterone levels [16]. 

Monitor serum DHEA-S (aim for the middle range of normal levels in healthy young people) and free testosterone level. 

A complete physical examination and laboratory analysis are needed to rule out secondary causes and to assess kyphosis and back pain. Laboratory testing may include complete blood count, liver function tests, creatinine, urea nitrogen, calcium, phosphorus, alkaline phosphatase, albumin, thyroid-stimulating hormone, free testosterone, 25-hydroxyvitamin D, and 24-hour urine concentrations of calcium and phosphorus. Urine or serum biomarkers (e.g., cross-linked N-telopeptides of type 1 collagen, osteocalcin) are sometimes used. 

Harman SM et al Longitudinal effects of aging on serum total and free testosterone levels in healthy men. Baltimore Longitudinal Study of Aging. J Clin Endocrinol Metab 2001 86 724. [PMID 11158037]... 

Thyroid Effects. Limited information is available on thyroid effects in PBDE-exposed humans. There are suggestive occupational data as shown by effects that included increased serum FSH, low or borderline low serum T4, and increased thyroid antimicrosomal antibody titers in workers exposed to decaBDE and/or unspecified PBBs. There was no clear association between plasma levels of 2,2, 4,4-tetraBDE and thyroid hormone levels (free and total T3 and T4, TSH, free testosterone, follicle-stimulating hormone, lutenizing hormone, and prolactin) in men who consumed varying amounts of fatty fish from the Baltic Sea. Based on consistent evidence in animals, as summarized below, the thyroid is particularly sensitive to PBDEs and is a likely target of toxicity in exposed humans. 

Polybrominated Diphenyl Ethers. A limited amount of epidemiological irrformation is available for PBDEs. Plasma levels of various organohalogen compounds, including the congener 2,2, 4,4-tetraBDE, as well as serum hormone levels (free and total T3 and T4, TSH, free testosterone, follicle-stimulating... 

In an open comparative study of androgenetic alopecia in 90 men oral finasteride (1 mg/day for 12 months n = 65) was compared with 5% topical minoxidil solution twice daily (n = 25) (22). The cure rates were 80% for oral finasteride and 52% for topical minoxidil. The adverse effects were all mild, and did not lead to withdrawal of treatment. Of the 65 men given oral finasteride, six had loss of libido, and one had an increase in body hair at other sites irritation of the scalp was seen in one of those who used minoxidil. These adverse events disappeared as soon as the treatment was withdrawn. The laboratory data did not show any statistically or clinically significant changes from baseline values to the endpoint, except for the serum total testosterone concentration, which was increased, and free testosterone and serum prostate-specific antigen in the finasteride group which were reduced from baseline values. 

Azizi et al. (1995) investigated changes in serum concentrations of reproductive hormones and sperm counts in men who had been exposed to sulfur mustard during wartime. In 16 individuals, serum free and total testosterone and dehydroepiandrosterone were markedly decreased in the first five weeks after exposure but levels returned to normal by 12 weeks. In 28 of 42 men evaluated one to three years after exposure, sperm counts were less than 30 million ceUs/mL and follicle-stimulating hormone was increased compared to controls having sperm counts above 60 million cells/mL. Testicular biopsy of the test subjects revealed partial or complete arrest of spermatogenesis. 

Either serum or heparinized plasma is used to measure total or free testosterone. Testosterone is subject to a diurnal variation, reaching a peak concentration between 0400 hours and 0800 hours. Therefore, morning specimens are preferred. Specimens are stable for a week (men) or 3 days (women) refrigerated and for up to 1 year frozen at 20 No steroids, thyroid, ACTH, estradiol, or gonadotropin medications should be given for 48 hours before sample collection. Most assays are standardized for serum or heparinized plasma. Other anticoagulants such as ethylene-diaminetetraacetic acid (EDTA) may give different values. In certain RIA assays, presence of EDTA appears to cause a 10% decrease in total testosterone concentrations. ... 

Reference intervals for free testosterone and percent free testosterone in serum are listed in. Table 53-6 and in Chapter 5 261,336 q jjggg concentrations compare favorably with those obtained when using membrane ultrafiltration and gel filtration methods. Equilibrium dialysis is considered die reference method for determining free testosterone in serum. 

Gruschke A, Kuhl H. Validity of radioimmunological methods for determining free testosterone in serum. Fertil Steril 2001 76 576-82. 

Vermeulen A, Verdonck L, Kaufman JM. A critical evaluation of simple methods for the estimation of free testosterone in serum. J Chn Endocrinol Metab 1999 84 3666-72. 

Some men with osteoporosis possess clearly identifiable risk factors. In others, further investigation for secondary canses is warranted (see above patient assessment section). Men 70 years and older should have DXA tests to screen for osteoporosis. DXA standards state T-scores shonld be compared with a white male normative reference database, regardless of ethnicity. BMD determination shonld also be considered for men with a low-tranma fracture, prevalent vertebral deformity, glucocorticoid use, hypogonadism, alcoholism, or poor overall health. Measmement of serum free or total testosterone can also determine if hypogonadism is contributing to bone loss. 

Endocrine In 77 men with coronary heart disease atorvastatin 40-80 mg/day and for 12 weeks had no significant effects on serum total testosterone, free testosterone, sex hormone-binding globulin, luteinizing hormone, or follicle stimulating hormone compared with 83 men who took 10-20 mg/day [42 "]. 

Testosterone (T) Female Abdomen, forearm MDTS spray solution Pharmacokinetic parameters Average and maximum serum concentrations of free and total T were significantly higher after application to the forearm compared to the abdomen V... 

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