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Vitamin A (retinol) is a micronutrient critical for cell proliferation and differentiation. In adults, vitamin A and metabolites such as retinoic acid (RA) play major roles in vision, immune and brain functions and tissue remodelling and metabolism. This review presents the physiological interactions of retinoids and endocrine tissues and hormonal systems. Two endocrine systems have been particularly studied. In the pituitary, retinoids target the corticotrophs with a possible therapeutic use in corticotropinomas. In the thyroid, retinoids interfere with iodine metabolism and vitamin A deficiency aggravates thyroid dysfunction caused by iodine-deficient diets. Retinoids use in thyroid cancer appears less promising than expected. Recent and still controversial studies investigated the relations between retinoids and metabolic syndrome. Indeed, retinoids contribute to pancreatic development and modify fat and glucose metabolism. However, more detailed studies are needed before planning any therapeutic use. Finally, retinoids probably play more minor roles in adrenal and gonads development and function apart from their major effects on spermatogenesis.

Human semen quality is declining in many parts of the world, but the causes are ill defined. In rodents, impaired sperm production can be seen with early life exposure to certain endocrine-disrupting chemicals, but the effects of combined exposures are not properly investigated. In this study, we examined the effects of early exposure to the painkiller paracetamol and mixtures of human relevant endocrine-disrupting chemicals in rats. One mixture contained four estrogenic compounds; another contained eight anti-androgenic environmental chemicals and a third mixture contained estrogens, anti-androgens and paracetamol. All exposures were administered by oral gavage to time-mated Wistar dams rats (n = 16–20) throughout gestation and lactation. In the postnatal period, testicular histology was affected by the total mixture, and at the end of weaning, male testis weights were significantly increased by paracetamol and the high doses of the total and the anti-androgenic mixture, compared to controls. In all dose groups, epididymal sperm counts were reduced several months after end of exposure, i.e. at 10 months of age. Interestingly, the same pattern of effects was seen for paracetamol as for mixtures with diverse modes of action. Reduced sperm count was seen at a dose level reflecting human therapeutic exposure to paracetamol. Environmental chemical mixtures affected sperm count at the lowest mixture dose indicating an insufficient margin of safety for the most exposed humans. This causes concern for exposure of pregnant women to paracetamol as well as environmental endocrine disrupters.

Abstract

Growth hormone deficiency (GHD) is a clinical syndrome that can manifest either as isolated or associated with additional pituitary hormone deficiencies. Although diminished height velocity and short stature are useful and important clinical markers to consider testing for GHD in children, the signs and symptoms of GHD are not always so apparent in adults. Quality of life and metabolic health are often impacted in patients with GHD; thus, making an accurate diagnosis is important so that appropriate GH replacement therapy can be offered to these patients. Screening and testing for GHD require sound clinical judgment that follows after obtaining a complete medical history of patients with a hypothalamic-pituitary disorder and thorough physical examination with specific features for each period of life, while targeted biochemical testing and imaging are required to confirm the diagnosis. Random measurements of serum GH levels are not recommended to screen for GHD (except in neonates) as endogenous GH secretion is episodic and pulsatile throughout the lifespan. One or more GH stimulation tests may be required, but existing methods of testing might be inaccurate, difficult to perform, and can be imprecise. Furthermore, there are multiple caveats when interpreting test results including individual patient factors, differences in peak GH cut-offs (by age and test), testing time points, and heterogeneity of GH and IGF-I assays. In this article, we provide a global overview of the accuracy and cut-offs for diagnosis of GHD in children and adults, and discuss the caveats in conducting and interpreting these tests.

The implementation of high-throughput and deep sequencing methods in routine genetic diagnostics has significantly improved the diagnostic yield in patient cohorts with growth disturbances and becomes increasingly important as the prerequisite of personalized medicine. They provide considerable chances to identify even rare and unexpected situations; nevertheless, we must be aware of their limitations. A simple genetic test in the beginning of a testing cascade might also help to identify the genetic cause of specific growth disorders. However, the clinical picture of genetically caused growth disturbance phenotypes can vary widely, and there is a broad clinical overlap between different growth disturbance disorders. As a consequence, the clinical diagnosis and therewith connected the decision on the appropriate genetic test is often a challenge. In fact, the clinician asking for genetic testing has to weigh different aspects in this decision process, including appropriateness (single gene test, stepwise procedure, comprehensive testing), turnaround time as the basis for rapid intervention, and economic considerations. Therefore, a frequent question in that context is ‘what to test when’. In this review, we aim to review genetic testing strategies and their strengths and limitations and to raise awareness for the future implementation of interdisciplinary genome medicine in diagnoses, treatment, and counselling of growth disturbances.

TSH routine testing in hospitalized patients has low efficacy, but may be beneficial in a selected subgroup of patients. Our aim was to evaluate the efficacy of routine thyroid function tests among patients admitted to internal medicine departments. It is a retrospective study. A randomly selected cohort of hospitalized patients with abnormal thyroid-stimulating hormone (TSH) blood tests drawn as part of admission protocol. Patient data were collected from the electronic medical files and analyzed for its efficacy. TSH as a screening test was proven unnecessary in 75% (174) of the study population. Leading causes were non-thyroidal illness syndrome, drugs affecting the test results and subclinical disorders. TSH testing was found to be clinically helpful in only 9 patients; however, all of them had other clinical need for TSH testing. We found a clinically abnormal TSH in 20 patients, hypothyroidism in 11 patients and thyrotoxicosis in 9 patients. Low efficacy ascribed to TSH screening test by this study correlates with recent recommendations that indicate TSH screening in admitted patients only with accompanying clinical suspicion. Most probably, the majority of patients found by screening to have thyrotoxicosis have non-thyroidal illness or drug effects so the threshold for FT4 to diagnose overt thyrotoxicosis should be higher than that in ambulatory patients. In elderly patients, clinically relevant TSH disturbances are more frequent and are harder to diagnose, therefore, TSH screening in this group of patients might be beneficial.

The water deprivation test is the gold standard test to differentiate central or nephrogenic diabetes insipidus (DI) from primary polydipsia (PP) in patients with polyuria and polydipsia. Few studies have addressed the diagnostic performance of this test. The aim of this retrospective cohort study was to evaluate the diagnostic performance of the standard water deprivation test, including plasma arginine vasopressin (AVP) measurements, in 40 consecutive patients with polyuria. We compared initial test results with the final clinical diagnosis, i.e., no DI, central DI, or nephrogenic DI. The median length of follow-up was 8 years. In a subset of ten patients, the novel marker copeptin (CP) was measured in plasma. Using the final diagnosis as a gold standard, a threshold for urine osmolality of >800 mOsmol/kg after water deprivation yielded a sensitivity and specificity of 96 and 100%, respectively, for diagnosing PP. Sensitivity increased to 100% if the cut-off value for urine osmolality was set at 680 mOsmol/kg. Plasma AVP levels did not differ between patient groups and did not differentiate among central DI, nephrogenic DI, or PP. In all three patients with central DI, plasma CP was <2.5 pmol/l with plasma osmolality >290 mOsmol/kg, and >2.5 pmol/l in patients without DI. The optimal cut-off value for differentiating PP from DI during a water deprivation test was urine osmolality >680 mOsmol/kg. Differentiating between central and nephrogenic DI should be based on clinical judgment as AVP levels did not discriminate.