Sex hormone-binding globulin in congenital adrenal hyperplasia

BACKGROUND

Sex hormone-binding globulin biosynthesis is influenced by three hormonal systems: gonadal, insular and thyroid. Congenital adrenal hyperplasia is characterized by overproduction of adrenal androgens associated with impaired insulin sensitivity, hyperinsulinemia and often also with hypothyroidism. Only scarce data are available concerning congenital adrenal hyperplasia. The objective of this study was to determine the distribution of sex hormone-binding globulin and free testosterone levels in these patients and to what extent these values correlate with actual 17-hydroxyprogesterone and androstenedione levels, which are commonly used for monitoring of treatment effectiveness.

MATERIALS AND METHODS

A total of 300 retrospective laboratory records of 78 males and boys and 456 records of 162 girls and premenopausal women with diagnosis of congenital adrenal hyperplasia under common substitution treatment were evaluated statistically. The data were divided artificially into groups of low, normal and high levels, with respect to physiological concentrations for each sex and age. The percentages of the total in each group were calculated.

RESULTS

Whereas an almost Gaussian distribution occurred for males, the data for females displayed a considerable shift to low sex hormone-binding globulin and accordingly high free testosterone levels. Sex hormone-binding globulin levels did not correlate with 17-hydroxyprogesterone.

CONCLUSION

Low sex hormone-binding globulin levels in congenital adrenal hyperplasia, at least in females, reflect their involvement in insular and eventually thyroid axes, rather than the effectiveness of substitution.

Steroid metabolome in fetal and maternal body fluids in human late pregnancy

Despite the extensive research during the last six decades the fundamental questions concerning the role of steroids in the initiation of human parturition and origin and function of some steroids in pregnancy were not definitely answered. Based on steroid metabolomic data found in the literature and our so far unpublished results, we attempted to bring new insights concerning the role of steroids in the sustaining and termination of human pregnancy, and predictive value of these substances for estimation of term. We also aimed to explain enigmas concerning the biosynthesis of progesterone and its bioactive catabolites considering the conjunctions between placental production of CRH, synthesis of bioactive steroids produced by fetal adrenal, localization of placental oxidoreductases and sustaining of human pregnancy. Evaluation of data available in the literature, including our recent findings as well as our new unpublished data indicates increasing progesterone synthesis and its concurrently increasing catabolism with approaching parturition, confirms declining production of pregnancy sustaining 5β-pregnane steroids providing uterine quiescence in late pregnancy, increased sulfation of further neuroinhibiting and pregnancy sustaining steroids. In contrast to the established concept considering LDL cholesterol as the primary substrate for progesterone synthesis in pregnancy, our data demonstrates the functioning of alternative mechanism for progesterone synthesis, which is based on the utilization of fetal pregnenolone sulfate for progesterone production in placenta. Close relationships were found between localization of placental oxidoreductases and consistently higher levels of sex hormones, neuroactive steroids and their metabolites in the oxidized form in the fetus and in the reduced form in the maternal compartment.

Effects of valproate and carbamazepine monotherapy on neuroactive steroids, their precursors and metabolites in adult men with epilepsy

Only limited data is available concerning the role of unconjugated Δ(5) C19-steroids and almost no data exists regarding the neuroactive C21 and C19 3α-hydroxy-5α/β-metabolites in men with epilepsy. To evaluate the alterations in serum neuroactive steroids and related substances in adult men with epilepsy on valproate and carbamazepine monotherapy, we have measured 26 unconjugated steroids, 18 steroid polar conjugates, gonadotropins and sex hormone binding globulin (SHBG) in 6 and 11 patients on valproate and carbamazepine monotherapy, respectively, and in 19 healthy adult men, using the GC-MS and immunoassays. Decreased testosterone, free androgen index, free testosterone, androstenediol, 5α-androstane-3α,17β-diol (androstanediol), androsterone, epiandrosterone, DHEA, 7β-hydroxy-DHEA, and DHEAS levels were associated with epilepsy per se. Valproate (VPA) therapy increased 5α-dihydrotestosterone, androsterone, epiandrosterone, DHEA, DHEAS, and 7β-hydroxy-DHEA levels. Decrease in pregnenolone and 17-hydroxypregnenolone were associated with epilepsy with no effect of antiepileptic drugs (AEDs). Alternatively, the increase in progesterone levels was linked to epilepsy and VPA further increased progesterone levels. Reduced steroid 20α-hydroxy-metabolites and cortisol were connected with epilepsy without an effect of AEDs. Carbamazepine induced only slight decrease in isopregnanolone, 5α,20α-tetrahydroprogesterone, and androstanediol levels.

A novel radioimmunoassay of 16alpha-hydroxy-dehydroepiandrosterone and its physiological levels

16alpha-Hydroxy-dehydroepiandrosterone (16alpha-OH-DHEA) belongs to the products of extensive DHEA metabolism in mammalian tissues. It is a precursor of 16alpha-hydroxylated estrogens, increased levels of which are associated with autoimmune disorders. A highly specific radioimmunoassay of unconjugated 16alpha-OH-DHEA was developed and evaluated. Polyclonal rabbit antisera were raised against 3beta,16alpha-dihydroxy-17,19-dione-19-O-(carboxymethyloxime) and 3beta,16alpha-dihydroxy-7,17-dione-7-O-(carboxymethyloxime) BSA conjugates. Two methods were used for preparation of the conjugates. Homologous radioiodinated derivatives with tyrosine methyl ester were prepared as tracers. While antisera to 7-CMO cross-reacted with DHEA as much as by 58%, the cross-reaction of the chosen antiserum prepared via 19-oxogroup by micellar conjugation technique with 16beta-OH-DHEA was only 0.13% and with all other structurally related steroids, including DHEA were lower than 0.01%. The detection limit was 0.017 pmol (5.7 pg)/tube, the average intra- and inter-assay coefficients of variation were 8.2 and 11.4%, respectively. Mean recovery of serum spiked with 16alpha-OH-DHEA varied between 80 and 110%, the results were independent on sample dilution. 16alpha-OH-DHEA concentrations in 18 randomly selected sera, including 6 samples from patients with thyroid cancer were compared with results obtained by earlier GC-MS method. Physiological levels of 16alpha-OH-DHEA in 316 sera (184 females and 132 males) analyzed so far varied between 0.0 and 1.86 nmol/l.

A novel radioimmunoassay of 7-oxo-DHEA and its physiological levels

A novel radioimmunoassay (RIA) of unconjugated 7-oxo-dehydroepiandrosterone (7-oxo-DHEA) in human serum was developed for the first time. This steroid is an intermediate in the biosynthesis of immunomodulatory 7-hydroxylated DHEA metabolites, and has been shown to possess thermogenic properties. The method employs polyclonal rabbit antiserum to (19E)-3beta-hydroxy-7,17,19-trione-19-O-(carboxymethyloxime):BSA conjugate and a homologous radioiodinated derivative with tyrosine methyl ester. The cross reactivity of the antiserum with structurally closest 7-hydroxyepimers of DHEA was lower than 1.7%, with DHEA 0.4%, with all other related steroid less than 0.4%. The method includes ether extraction of serum (0.5 ml), followed by RIA. Its detection limit was 0.06 pmol (18 pg)/tube, the average intra- and inter-assay coefficients of variation were 4.1% and 8.3%, respectively. Mean recovery of serum spiked with 7-oxo-DHEA varied between 78.8% and 112%. Its levels in three serum pools were compared with a low-resolution gas chromatography-mass spectrometry method with satisfactory results. The method has been used for determination of 7-oxo-DHEA in serum samples of 215 subjects (91 males and 124 females) without overt endocrine disorders, aged 5-71 years. The over-all mean+/-S.D. was 0.280+/-0.227, the median 0.239 nmol/l. No significant sex differences were recorded. The only group which differed significantly from all other ones were males below 10 years, significantly lower values than in other age groups were found also in the first two age groups of females.