Late-onset hypogonadism: Beyond testosterone - Abstract

Late-onset hypogonadism is defined as a combination of low testosterone (T) levels and typical symptoms and signs.

A major area of uncertainty is whether T concentrations are always really sufficient to fully reflect Leydig cell (dys)function. Mild testicular alteration could be diagnosed only by additional biochemical markers, such as luteinizing hormone (LH) and 25-hydroxyvitamin D levels. These markers help in identifying the so-called "subclinical" hypogonadism (normal T, high LH levels). Patients with hypogonadism have frequently low levels of 25-hydroxyvitamin D due to impairment of the hydroxylating enzyme CYP2R1 in the testis. However, no data have been published dealing with the best treatment option (cholecalciferol - the Vitamin D precursor, or calcidiol - 25-hydroxylated form of Vitamin D) in these patients. We studied 66 patients with classic hypogonadism (total T [TT] < 12 nmol l-1 , LH ≥ 8 IU l-1 ) (n = 26) and subclinical hypogonadism (TT ≥ 12 nmol l-1 , LH ≥ 8 IU l-1 ) (n = 40) and low 25-hydroxyvitamin D (< 50 nmol l-1 ). Subjects received cholecalciferol (5000 IU per week) (n = 20) or calcidiol (4000 IU per week) (n = 46), and 25-hydroxyvitamin D and parathyroid hormone (PTH) were evaluated after 3 months of therapy. Supplementation with calcidiol significantly increased 25-hydroxyvitamin D and significantly decreased PTH levels in both groups of men with hypogonadism (primary, n = 16 and subclinical, n = 30), whereas supplementation with cholecalciferol did not modify their levels. This study shows for the first time that the administration of the 25-hydroxylated form of Vitamin D (calcidiol), and not the administration of the precursor cholecalciferol, restores 25-hydroxyvitamin D levels in subjects with hypogonadism.

Written by:
Foresta C, Calogero AE, Lombardo F, Lenzi A, Ferlin A.   Are you the author?
Department of Medicine and Centre for Human Reproduction Pathology, University of Padova, Padova 35128, Italy.

Reference: Asian J Androl. 2014 Sep 16. Epub ahead of print.
doi: 10.4103/1008-682X.135985

PubMed Abstract
PMID: 25248651 Androgen Deficiency Section