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DIAGNOSTIC SIGNIFICANCE OF FREE SALIVARY TESTOSTERONE
Vertkin, W., Goncharov,N.P., Katsya,G.V. Dobracheva, A.D., Nizhnik,
A.N. Koryakin, M.V. National Center of Endocrinology,
Dm. Ulyanova Street, 11, 117036, Moscow, Russia,
and Ziemann, W. IBL-Hamburg, Germany (see poster)
Project Description Saliva has attracted the attention of
researchers for many years, since salivary glands
possess the very particular feature of passing (by
passive filtration) some blood components, including
free steroids, not bound with SHBG and albumin, through
the membrane barrier into the salivary ducts. The
introduction by IBL of a novel ultrasensitive LIA
technology for direct determination of free testosterone
in microvolumes of biological materials, including
saliva, opens new possibilities in the assessment
of androgenic status both in men and women. Aims of
our study were: · Evaluation of diagnostic significance
of LIA technology for determination of free testosterone
in saliva, using different clinical models of androgenic
status. · Analyzing possible correlation between free
testosterone concentration in saliva and calculated
free testosterone and total testosterone level in
blood.
Materials and methods To evaluate the diagnostic significance
of IBL technology of salivary free testosterone measurement
we selected the following groups of volunteers, consisting
of men and women: 1. Healthy male volunteers, age
21 - 50 (n=16). 2. Male patients different forms of
androgen deficiency (total T < 10 nmol/l, normal range
11-35 nmol/l) (n=14). Mean concentrations of free
testosterone in saliva of 16 healthy men in the morning
(8:30-9:30) varied within the range 75-162 pg/ml (10,
90 percentiles), median 108 pg/ml. Individual and
mean concentrations of salivary free testosterone
and free testosterone in blood in healthy men practically
match each other. In 14 men with androgen deficiency,
aged 22-68 yrs, mean concentration of total testosterone
in the blood was 6.7 nmol/l (1.2-10.8 nmol/l) (median
and 10-90 percentiles). Coefficient of variation of
free salivary testosterone concentration in men with
androgen deficiency during the day was 31% (18-68%)
and did not differ significantly from that of healthy
men: 24 (11-45%). Significance was determined by Mann-Whitney
test. We conclude that the direct determination of
free testosterone in saliva is a more adequate instrument
for establishing androgenic status in comparison with
mathematical calculation, as in the latter case the
calculated level of free testosterone in blood depends
on correct measurement of two parameters: total testosterone,
and SHBG.
Conclusion IBL LIA technology for salivary testosterone measurement
gives a good reflection of the unbound testosterone
in plasma. Since free fraction is thought to determine
exposure to the tissues, salivary testosterone concentrations
should give a better indication of biologically active
steroid than total plasma levels, especially in conditions
of altered SHBG-binding.
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