Searchable abstracts of presentations at key conferences in endocrinology

ea0041ep954 | Steroid metabolism + action | ECE2016

First generation testosterone assays are influenced by sex hormone binding globulin concentrations as evidenced during oral contraceptive use and pregnancy

Heijboer Annemieke , Savelkoul Edo , Kruit Adrian , Endert Erik , Blankenstein Marinus

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...

ea0081p206 | Thyroid | ECE2022

Discordance between fT4 and TSH concentrations during levothyroxine treatment

Jansen Heleen , Bult Marijn , Bisschop Peter H. , Boelen Anita , C Heijboer Annemieke , Hillebrand Jacquelien

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...

ea0041ep961 | Steroid metabolism + action | ECE2016

Increase in insuline-like growh factor levels during cross-sex hormone treatment in transgender persons

Nota Nienke , Dekker Marieke , Klaver Maartje , Wiepjes Chantal , Heijboer Annemieke , den Heijer Martin

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 ...

ea0037gp.04.06 | Steroids | ECE2015

Testosterone, androstenedione, cortisol, and cortisone levels in unstimulated, stimulated, and parotid saliva

Buttler Rahel M , Bagci Esra , Brand Henk , Blankenstein Marinus A , Heijboer Annemieke C

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...

ea0037gp.10.05 | Calcium, Vitamin D and Bone | ECE2015

Effect of 1-year cross-sex hormonal treatment on bone mineral density of the lumbar spine in transgender patients

Vlot Mariska , Klaver Maartje , Lips Paul , de Jongh Renate , Heijboer Annemieke , den Heijer Martin

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 ...

ea0037gp.11.05 | Calcium, Vitamin D and Bone (1) | ECE2015

Determination of reference values for serum total 1,25-dihydroxyvitamin D3 using an extensively validated 2D ID-UPLC–MS/MS method

Dirks Niek , Martens Frans , Vanderschueren Dirk , Billen Jaak , Ackermans Mariette , Endert Erik , Blankenstein Marinus , Heijboer Annemieke

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...

ea0037ep130 | Steroids, development and paediatric endocrinology | ECE2015

Serum prolactin levels in transgender persons before and during cross-sex hormonal treatment

Nota Nienke , Klaver Maartje , den Heijer Martin , Dekker Marieke , Heijboer Annemieke

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...

ea0035p946 | Steroid metabolism and action | ECE2014

Measurement of testosterone, androstenedione and dehydroepiandrosterone (DHEA) serum levels using isotope-dilution liquid-chromatography tandem mass spectrometry (ID-LC-MS/MS)

Buttler Rahel M , Martens Frans , Ackermans Mariette T , Blankenstein Marinus A , Heijboer Annemieke C

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, ...

ea0022p736 | Steroid metabolism & action | ECE2010

Measurement of testosterone in muscle tissue using microdialysis: preliminary data

Wester Vincent , Bui Hong , Heijboer Annemieke , Blankenstein Rien , de Ronde Willem

Introduction: For diagnostic purposes, total-testosterone levels are generally assessed in plasma. However, as the primary site of action of testosterone is in tissue, evaluation of the distribution of testosterone in tissue fluids could give enhanced insight into the (patho)physiological state. Clinical microdialysis allows for sampling at tissue level based on diffusion.Objective: To compare the increase in testosterone levels in tissue and plasma afte...

ea0073aep592 | Reproductive and Developmental Endocrinology | ECE2021

Spuriously high testosterone concentrations testosterone gel users: A marker for detection

Schaper Sophie , Wiepjes Chantal , den Heijer Martin , Beukhof Carolien , Heijboer Annemieke C

ContextContamination of collected blood samples by application of testosterone gel near the venipuncture site can cause spuriously elevated serum testosterone concentrations. Often this will be detected only in case of extreme discrepancies between lab result and clinical effects. Because in vitro testosterone cannot be metabolized as the testosterone in vivo we hypothesized that measuring estradiol, as a metabolite of testosterone after aromati...