Publications by authors named "Tom Fiers"

Objectives: To compare clinical laboratory workflows for the assessment of androgens in men, focusing on total testosterone (T), sex hormone-binding globulin (SHBG) and free T, in clinical laboratories throughout Europe.

Methods: An internet-based survey that included questions related to pre-analytical, analytical and post-analytical phases of androgen measurements was distributed between December 2022 and December 2023 by clinical laboratory/chemistry and endocrine societies. A total of 124 unique records from clinical laboratories in 27 European countries were analyzed.

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Background: Obesity is associated with varying degrees of metabolic dysfunction. In this study, we aimed to discover markers of the severity of metabolic impairment in men with obesity via a multiomics approach.

Methods: Thirty-two morbidly men with obesity who were candidates for Roux-en-Y gastric bypass (RYGB) surgery were prospectively followed.

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Sexual dimorphism influences cardiovascular outcomes in type 1 diabetes (T1D), with women facing a higher relative risk of macrovascular events compared to men, especially after menopause. This study hypothesizes that abnormalities in intermediate metabolism may be associated with cardiac autonomic neuropathy (CAN) in T1D. We aim to assess low molecular weight metabolites (LMWM) as markers of CAN in T1D, considering the effects of sexual dimorphism and age.

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Study Question: Is resting energy expenditure (REE) altered in women with polycystic ovary syndrome (PCOS)?

Summary Answer: Women with PCOS have a reduction in REE, when corrected for fat-free mass, independent of PCOS clinical phenotypes and BMI categories.

What Is Known Already: Obesity is an important issue in women with PCOS, in terms of frequency and pathophysiological implications. It has been hypothesized that obesity may be favoured by alterations in REE, but the studies have been limited and conflicting.

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Article Synopsis
  • Genetic variation in sex hormone-binding globulin (SHBG) can influence testosterone (T) levels, potentially leading to inaccurate diagnoses if not considered.
  • A study of 999 healthy men (ages 25 to 45) explored how specific genetic variations (SNPs) in SHBG affect the measured and estimated levels of free testosterone.
  • Results showed that while certain SNPs led to significant changes in total testosterone and SHBG levels, the impact on calculated or measured free testosterone was minimal, with a notable trend observed only in rs6259 homozygotes.
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Knowledge of whether prenatal exposure to ambient air pollution disrupts steroidogenesis is currently lacking. We investigated the association between prenatal ambient air pollution and highly accurate measurements of cord blood steroid hormones from the androgenic pathway.This study included 397 newborns born between the years 2010 and 2015 from the ENVIRONAGE cohort in Belgium of whom six cord blood steroid levels were measured: 17α-hydroxypregnenolone, 17α-hydroxyprogesterone, dehydroepiandrosterone, pregnenolone, androstenedione, and testosterone.

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Objective: Androgen levels decline from early adulthood and decreases are steeper in men with increasing body mass index. It is, however, unclear to what extent changes in other indices of body composition and metabolism associate with changes in sex steroid levels in healthy men. Therefore, this study investigated longitudinal changes in body composition and metabolic health in relation to sex steroid levels in healthy adult men.

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Introduction: Breast cancer is the most common cancer type in women worldwide. Due to hormone receptor positivity in the majority of the breast cancer tumours is endocrine therapy a crucial part in the treatment landscape of breast cancer. Endocrine therapy consists of the use of selective oestrogen-receptor modulators or aromatase inhibitors.

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Background: Sex differences characterize cardiovascular outcomes in patients with type 1 diabetes. Cardioautonomic neuropathy is a common complication of type 1 diabetes that associates increased morbi-mortality. Data regarding the interplay between sex and cardiovascular autonomic neuropathy are scarce and controversial in these patients.

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Salivary steroid immunoassays are widely used in psychoneuroendocrinological studies of menstrual cycle phase, puberty, and menopause. Though manufacturers advertise their assays as suitable, they have not been rigorously validated for these purposes. We collated data from eight menstrual cycle studies across > 1200 female participants and > 9500 time points.

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Background: Initiating feminizing gender-affirming hormone therapy (GAHT) in transgender women causes a steep decline in serum testosterone. It is unknown if testosterone concentrations change further and whether adrenal androgen levels change during feminizing GAHT and after gonadectomy. This limits clinical decision making in transgender women with symptoms attributed to GAHT or gonadectomy.

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Bone metabolism in men is in part determined by sex steroid exposure. This is especially clear during puberty and senescence but it remains to be established whether declines in sex steroid levels during young and middle adulthood are associated with changes in bone mass and size. This study investigated changes in bone mineral content (BMC), areal bone mineral density (aBMD), volumetric BMD (vBMD), and bone size in relation to sex steroid levels in 999 young adult men (age 24-46 years) of whom 676 were re-evaluated after a mean period of 12 years.

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Introduction: This study investigates peri-pubertal changes in bone turnover markers, Wnt-signalling markers, insulin-like growth factor-1 (IGF-1) and sex steroid levels, and how they reflect skeletal development in peri-pubertal boys.

Materials And Methods: Population-based study in 118 peri-pubertal boys from the NINIOS cohort (age range at baseline 5.1-17.

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Objectives: Diabetes mellitus is a major public health problem. Hemoglobin A (HbA) is a key laboratory parameter in the management of diabetes patients. However, in diabetes monitoring, interpretation of HbA results is hampered by the important interindividual variation in red blood cell (RBC) life span.

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Context: Recent data suggested that 11-oxygenated androgens may be the preponderant circulating androgens in women with PCOS. However, the pathophysiological significance of these hormones remains unclear.

Objective: The aim of this study was to evaluate the relationships between serum 11-OH testosterone (11-OHT) and 11-keto testosterone (11-KetoT) and clinical and biochemical hyperandrogenism, as well as the metabolic parameters, in women with PCOS.

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Introduction: Health-care organizations are facing a high burden of ergonomic occupational accidents, and prevention is a continuous point of interest. In this manuscript, we describe the characteristics of ergonomic accidents in a large Belgian university hospital and discuss the value of near misses.

Methods: Combining databases, we identified the frequency [number of accidents × 10 hours worked per year], severity (number of days off work × 10 hours worked per year), and profile of the victims of occupational ergonomic accidents (with absence from work) or incidents or near-misses (without absence from work).

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Context: Few studies have explored in vivo insulin action on substrate use in women with PCOS. In particular, no data are available in women with different PCOS phenotypes.

Objective: The aim of the study was to evaluate insulin action on glucose (Gox) and lipid (Lox) oxidation, nonoxidative glucose metabolism (Gnonox), and serum free fatty acids (FFAs) in different PCOS phenotypes.

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Objective: Men with obesity often have low total and, with increasing adiposity, also low free testosterone (T) levels, which can partially restore during weight loss. Although this is partly explained by lower sex hormone binding globulin (SHBG) production and hypothalamic-pituitary downregulation, it is still not unravelled whether changes in androgen metabolism contribute to this phenomenon. Therefore, early changes in urinary excretion of T and its metabolites, during weight loss, in men with obesity are investigated.

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Context: Androgen levels have been shown to decline in aging men. However, there is no consensus on the effect of aging, (changes in) body mass index (BMI), lifestyle factors, and intercurrent disease.

Objective: Investigating longitudinal changes in serum androgen levels in healthy men in relation to body composition, lifestyle factors, and intercurrent disease.

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Article Synopsis
  • The study investigates the relationship between metabolic clearance rate of insulin (MCRI) and various characteristics of women with polycystic ovary syndrome (PCOS) who have normal glucose tolerance.
  • About two-thirds of the women showed impaired MCRI, which correlated with differences in factors like body fat, insulin secretion, and androgen levels.
  • The findings suggest that reduced MCRI contributes to hyperinsulinemia in PCOS, with serum androgen levels being a significant predictor of this reduction.
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Objective: Guidelines recommend using fasting samples to evaluate testosterone (T) levels in men, as free and total T levels decrease postprandially. However, it is not clear whether these dynamics are affected by age or obesity. This could be relevant given the obesity epidemic, ageing population and the barrier for screening which fasting could impose.

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Men with obesity often present with low testosterone (T) and sex hormone-binding globulin (SHBG) levels. Several mechanisms for this have been proposed, but as SHBG is secreted by hepatocytes and sex steroids undergo hepatic metabolization, this study investigates whether severity and histological components of nonalcoholic fatty liver disease (NAFLD) are associated with sex steroid levels in obese men. This cross-sectional study included 80 obese men (age: 46 ± 11 years; body mass index: 42.

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: To provide insight in patterns and causes of aberrant thyroid function tests (TFT) and to propose a practical approach for clinicians.: Starting from an illustrative case report, an extensive literature search was performed, resulting in a narrative literature review.: TFT that cannot be explained by the negative feedback principle of the hypothalamo-pituitary-thyroid axis are a challenge for every clinician.

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Article Synopsis
  • Thyroid dysfunction affects about 10% of the population and is linked to higher risks of heart problems and death.
  • A large analysis of genetic studies involving 72,167 individuals identified 109 genetic variants related to thyroid function and disease.
  • Researchers found a new thyroid hormone transporter and metabolizing enzyme, which could lead to new treatment options for thyroid-related issues.
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Context: Assessment of free testosterone (FT) might help evaluate androgen status in patients with borderline total testosterone (T) and/or altered sex hormone-binding globulin (SHBG) levels. However, the validity of different methods to measure FT is debatable.

Methods: Serum from 183 women and 146 men was analyzed using equilibrium dialysis (ED), with FT directly measured by liquid chromatography-tandem mass spectrometry.

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