Endocrine Abstracts

Introduction: The quality of testosterone assays has been a matter of debate for several years. Known limitations of testosterone immunoassays are the cross-reactivity with other steroids and a high variation in the low concentration range. We hypothesized that one of the additional limitations of testosterone immunoassays is an ineffective displacement of testosterone from its binding protein.Methods: Thirty samples from women not using oral contracepti...

Background: Vitamin D deficiency is very common in older persons. It is not clear how serum 25-hydroxyvitamin D (25(OH)D) levels change during aging.Objective: To examine longitudinal changes in serum 25(OH)D levels in two representative cohorts of Dutch older persons during 6 and 13 years of follow-up, respectively.Methods: Data of the Longitudinal Aging Study Amsterdam (LASA) were used, an ongoing cohort study in older persons. T...

Testosterone levels in normally cycling women are generally assumed to be elevated during ovulation. The clinical relevance of changing testosterone levels during the menstrual cycle, however, is unclear, due to poor performance of current direct immunoassays for testosterone at low concentrations.An isotope dilution-liquid chromatography–tandem mass spectrometry (ID-LC–MS/MS) method with sufficient reliability and sensitivity1 was u...

Introduction: Physicians in our hospital notified the laboratory staff of a number of patients at the outpatient clinic with increased free T4 (fT4) concentrations without (complete) suppression of thyroid stimulating hormone (TSH). This phenomenon appeared to occur more frequently following implementation of a new automated fT4 immunoassay. The discordance between fT4 and TSH concentrations may be explained by analytical issues (not further explained here), incorrect referenc...

Background: Sex steroids probably stimulate growth-hormone secretion during puberty, which in turn contributes to the development of gender specific body characteristics. Hypothetically, adequate growth hormone levels in transgender persons are also important to achieve the best therapeutic results. The influence of cross-sex hormone treatment (CHT) at growth-hormone production in adult transgender persons is not yet elucidated.Objective: To investigate ...

In recent years measurement of steroid hormones like testosterone, androstenedione, cortisol, and cortisone has become increasingly important in both patient care and research. This is mainly due to the simple and non-invasive sample collection. We investigated in twenty healthy volunteers whether there is a difference between steroid hormone concentrations in unstimulated and parotid gland saliva as well as stimulated saliva collected while chewing without aid, using cotton a...

Background: Oestrogen can increase bone mineral density (BMD) by decreasing bone turnover, which is mainly seen in trabecular bone. Testosterone can increase bone size, but the effect on BMD is less clear. Cross-sex hormonal treatment (CSHT) in transsexuals can therefore affect the BMD. For example, in male-to-female individuals (MtFs) a lower BMD before start of CSHT has been described in comparison to healthy control men.Objectives: To investigate the ...

1,25-dihydroxyvitamin D3, the hormonally active metabolite of vitamin D3, tightly controls calcium blood levels. An increase of 1,25-dihydroxyvitamin D3 leads to an increase in calcium concentration with calcium originating from various resources, including bone tissue. To assess a patient’s vitamin D status the precursor metabolite 25-hydroxyvitamin D3 is determined. However, measurement of 1,25-dihydroxyvitamin D is required w...

Introduction: Gender dysphoria refers to the incongruence between the subject’s experienced sex on the one hand and the assigned sex on the other hand. Several studies assume a relationship between oestrogen substitution therapy and serum prolactin levels.Aim: The aim of this study is to get more insight into the effect and time-course of changes in serum prolactin levels during cross-sex hormone therapy.Methods: This prospect...

The adrenal and gonadal androgens testosterone, androstenedione and dehydroepiandrosterone (DHEA) play an important role in sexual development and fertility as well as in several other processes. We developed a method to assess serum testosterone, androstenedione and DHEA levels in one run using isotope-dilution liquid-chromatography tandem mass spectrometry (ID-LC-MS/MS). Sample preparation consisted of addition of internal standards (13C3-testosterone, ...