The need for the GREAT+ score to predict relapse in Graves' disease: a questionnaire among patients and internal medicine specialists.

PURPOSE: Graves' disease (GD) is an auto-immune cause of hyperthyroidism. First-line treatment often consists of a 12-18 month course of antithyroid drugs (ATD). After discontinuation of ATD, GD relapses in approximately 50% of patients. The 'Graves recurrent event after therapy+ ' (GREAT+) score may predict individual relapse chances after ATD discontinuation more accurately based on clinical and laboratory parameters at diagnosis. We investigated the need for the GREAT+ score through an online questionnaire among GD patients and physicians treating GD. METHODS: An anonymous online questionnaire was distributed to patients and physicians between June 2022 and August 2023. RESULTS: The questionnaire was completed by 532 patients and 44 physicians. Results showed that 94% of patients were interested in knowing their GREAT+ score at the start of treatment. 55% would consider definite treatment (radioiodine/thyroidectomy) as first-line treatment in case of a high relapse chance. 98% of the physicians indicated the GREAT + score would support patient counseling. 84% may change their advice for first-line treatment if a patient has a high relapse chance based on the score. CONCLUSION: Patients and physicians considered the GREAT+ score as a valuable addition to the current available information which could change treatment decisions. Therefore, external validation of the GREAT+ score is justified to implement this score in clinical practice.

Harmonization of commercial assays for PINP; the way forward.

International Federation of Clinical Chemistry and Laboratory Medicine and The International Osteoporosis Foundation Joint Committee on Bone Metabolism believes that the harmonization of PINP assays is an achievable and practical goal. INTRODUCTION: In order to examine the agreement between current commercial assays, a multi-center study was performed for PINP in serum and plasma. METHODS: The automated methods for PINP (Roche Cobas and IDS iSYS) gave similar results. A significant proportional bias was observed between the two automated assays and the Orion radioimmunoassay (RIA) for PINP. RESULTS: Results from other published studies comparing PINP values among these three assays broadly support our findings. Taken together, these results confirm that harmonized PINP measurements exist between the two automated assays (Roche Cobas and IDS iSYS) when the eGFR is > 30 mL/min/1.73m2, but a significant bias exists between the Orion RIA and the two automated assays. CONCLUSION: Therefore, in subjects with normal renal function, PINP results reported by the Roche Cobas and IDS iSYS assays are similar and may be used interchangeably, and similar reference intervals and treatment targets could be applied for the two automated assays. Harmonization between the automated assays and the RIA is potentially possible with the use of common calibrators and the development of a reference method for PINP. This should also help ensure that any new commercial assay developed in the future will attain similar results. IOF and IFCC are committed to working together towards this goal with the cooperation of the reagent manufacturing industry.

A decrease in vitamin D levels is associated with methotrexate-induced oral mucositis in children with acute lymphoblastic leukemia.

PURPOSE: Children with acute lymphoblastic leukemia (ALL) are at increased risk of vitamin D deficiency, which might make them more susceptible to developing adverse events. Previous studies showed that low vitamin D levels were associated with an increased inflammatory mucosal state and impaired mucosal tissue barriers. We examined the prevalence of vitamin D deficiency and studied the association between vitamin D levels and methotrexate (MTX)-induced oral mucositis in pediatric ALL. METHODS: We assessed 25-hydroxyvitamin D (25(OH)D3) and 24,25-dihydroxyvitamin D (24,25(OH)2D3) levels in 99 children with ALL before the start of 4 × 5 g/m2 high-dose methotrexate (HD-MTX) (T0) and in 81/99 children after discontinuation of HD-MTX (T1). Two cutoff values for vitamin D deficiency exist: 25(OH)D3 levels < 30 and < 50 nmol/L. Oral mucositis was defined as grade ≥ 3 according to the National Cancer Institute Criteria. RESULTS: Vitamin D deficiency occurred in respectively 8% (< 30 nmol/L) and 33% (< 50 nmol/L) of the patients at T0, and more frequently in children > 4 years of age as compared to children between 1 and 4 years of age. A decrease in 25(OH)D3 levels during HD-MTX therapy was associated with developing severe oral mucositis (OR 1.6; 95% CI [1.1-2.4]). 25(OH)D3 and 24,25(OH)2D3 levels at T0 and the change in 24,25(OH)2D3 levels during therapy were not associated with the development of severe oral mucositis. CONCLUSIONS: This study showed that vitamin D deficiency occurs frequently in pediatric ALL patients above the age of 4 years. A decrease in 25(OH)D3 levels during MTX therapy was observed in children with ALL that developed severe oral mucositis.

Long-term effects of childhood cancer treatment on hormonal and ultrasound markers of ovarian reserve.

STUDY QUESTION: Which treatment-related factors are (dose-dependently) associated with abnormal hormonal and ultrasound markers of ovarian reserve in female childhood cancer survivors (CCSs)? SUMMARY ANSWER: Cyclophosphamide, procarbazine, a composite group of 'other alkylating agents', dactinomycin, doxorubicin, mitoxantrone, spinal radiotherapy (RT), abdominal/pelvic RT and total body irradiation were multivariably associated with abnormal ovarian reserve markers, with dose-effect relationships being established for procarbazine and abdominal/pelvic RT. WHAT IS KNOWN ALREADY: Female childhood cancer survivors are at an increased risk of reduced ovarian function and reserve, but knowledge regarding the long-term effects of individual chemotherapeutic (CT) agents and radiotherapy fields and their respective doses is limited. STUDY DESIGN, SIZE, DURATION: The DCOG LATER-VEVO is a nationwide retrospective cohort study in which measurements were performed between 2008 and 2014. In total, 1749 female 5-year CCSs, diagnosed before age 18 years between 1963 and 2002 and 1201 controls were invited for the study. PARTICIPANTS/MATERIALS, SETTING, METHODS: Ovarian reserve was assessed by anti-Müllerian hormone (AMH), follicle stimulating hormone (FSH), inhibin B levels, and antral follicle counts (AFC). The study was a multicentre study including all seven Dutch Centers for Paediatric Oncology/Haematology. MAIN RESULTS AND THE ROLE OF CHANCE: In total, 564 CCs and 390 controls participated in the clinical part of the study. Overall, 7.0-17.7% of CCSs and 2.4-13.6% of controls had abnormal ovarian reserve markers. Above age 35, significantly more CCSs than controls had abnormal ovarian reserve markers (AMH: 26% vs. 4%; AFC: 20% vs. 3%; inhibin B: 42% vs. 16%). For AMH and FSH, significant differences were also found below age 35. Cyclophosphamide, procarbazine, a group of 'other alkylating agents', dactinomycin, doxorubicin, mitoxantrone, spinal RT, abdominal/pelvic RT and total body irradiation were multivariably associated with at least one abnormal ovarian reserve marker. Dose-effect relationships were established for procarbazine and abdominal/pelvic RT. LIMITATIONS, REASONS FOR CAUTION: Despite the large scale of the study, dose-effect relationships could not be investigated for all types of treatment due to a limited numbers of participants for specific analyses. WIDER IMPLICATIONS OF THE FINDINGS: This study demonstrated that the majority of CCSs do not show signs of a reduced ovarian reserve. However, specific subgroups of CCSs appear to be associated with a high risk. Our results are important for counselling CCSs and future patients regarding parenthood and fertility preservation. STUDY FUNDING/COMPETING INTERESTS: This study was funded by the Dutch Cancer Society (Grant no. VU 2006-3622) and by the Children Cancer Free Foundation (Project no. 20). Philips Health Systems Benelux supported this study by providing three ultrasound systems and concomitant analytic software. There are no competing interests. TRIAL REGISTRATION NUMBER: NTR2922 http://www.trialregister.nl/trialreg/admin/rctview.asp?TC = 2922.

A comparison of UVb compact lamps in enabling cutaneous vitamin D synthesis in growing bearded dragons.

The effect of exposure to different UVb compact lamps on the vitamin D status of growing bearded dragons (Pogona vitticeps) was studied. Forty-two newly hatched bearded dragons (<24 h old) were allocated to six treatment groups (n = 7 per group). Five groups were exposed to different UVb compact lamps for two hours per day, with a control group not exposed to UVb radiation. At 120 days of age, blood samples were obtained and concentrations of 25(OH)D3 , Ca, P and uric acid were determined. In addition, plasma 25(OH)D3 concentration was determined in free-living adult bearded dragons to provide a reference level. Only one treatment resulted in elevated levels of 25(OH)D3 compared to the control group (41.0 ± 12.85 vs. 2.0 ± 0.0 nmol/L). All UVb-exposed groups had low 25(OH)D3 plasma levels compared to earlier studies on captive bearded dragons as well as in comparison with the free-living adult bearded dragons (409 ± 56 nmol/L). Spectral analysis indicated that all treatment lamps emitted UVb wavelengths effective for some cutaneous vitamin D synthesis. None of these lamps, under this regime, appeared to have provided a sufficient UVb dose to enable synthesis of plasma 25(OH)D3 levels similar to those of free-living bearded dragons in their native habitat.

Prolactin levels during short- and long-term cross-sex hormone treatment: an observational study in transgender persons.

The cause of prolactin alterations in transgender persons is often assigned to oestrogens, but the precise cause and time course during different phases of cross-sex hormone treatment (CHT) remain unclear. In this study, we prospectively examined prolactin levels in 55 female-to-males (FtMs) and 61 male-to-females (MtFs) during the first year of CHT. Because long-term prolactin data were not available in this population, we studied these levels in a retrospective population of 25 FtMs and 38 MtFs who underwent gonadectomy. FtMs were treated with testosterone and MtFs with estradiol, with or without the anti-androgen cyproterone acetate (CPA) (after gonadectomy CPA is cessated). During the first year of CHT, prolactin decreased with 25% (95CI: -33%, -12%) in FtMs and increased with 193% (95CI: 156%, 219%) in MtFs. Eighteen MtFs developed hyperprolactinemia (≥0.6 IU L-1 ). In the retrospective population, post-gonadectomy levels in FtMs were lower than baseline levels (-39%; 95CI: -51%, -20%) while in MtFs post-gonadectomy levels and baseline levels were comparable (-6%; 95CI: -24%, 15%). No hyperprolactinemia was found after gonadectomy. In conclusion, in FtMs, prolactin decreased consistently during CHT and in MtFs, prolactin increased during pre-surgical CHT but normalised after gonadectomy. It is likely that CPA induces increasing prolactin levels in MtFs.

Effects of 1,25(OH)2 D3 and 25(OH)D3 on C2C12 Myoblast Proliferation, Differentiation, and Myotube Hypertrophy.

An adequate vitamin D status is essential to optimize muscle strength. However, whether vitamin D directly reduces muscle fiber atrophy or stimulates muscle fiber hypertrophy remains subject of debate. A mechanism that may affect the role of vitamin D in the regulation of muscle fiber size is the local conversion of 25(OH)D to 1,25(OH)2 D by 1α-hydroxylase. Therefore, we investigated in a murine C2C12 myoblast culture whether both 1,25(OH)2 D3 and 25(OH)D3 affect myoblast proliferation, differentiation, and myotube size and whether these cells are able to metabolize 25(OH)D3 and 1,25(OH)2 D3 . We show that myoblasts not only responded to 1,25(OH)2 D3 , but also to the precursor 25(OH)D3 by increasing their VDR mRNA expression and reducing their proliferation. In differentiating myoblasts and myotubes 1,25(OH)2 D3 as well as 25(OH)D3 stimulated VDR mRNA expression and in myotubes 1,25(OH)2 D3 also stimulated MHC mRNA expression. However, this occurred without notable effects on myotube size. Moreover, no effects on the Akt/mTOR signaling pathway as well as MyoD and myogenin mRNA levels were observed. Interestingly, both myoblasts and myotubes expressed CYP27B1 and CYP24 mRNA which are required for vitamin D3 metabolism. Although 1α-hydroxylase activity could not be shown in myotubes, after treatment with 1,25(OH)2 D3 or 25(OH)D3 myotubes showed strongly elevated CYP24 mRNA levels compared to untreated cells. Moreover, myotubes were able to convert 25(OH)D3 to 24R,25(OH)2 D3 which may play a role in myoblast proliferation and differentiation. These data suggest that skeletal muscle is not only a direct target for vitamin D3 metabolites, but is also able to metabolize 25(OH)D3 and 1,25(OH)2 D3 . J. Cell. Physiol. 231: 2517-2528, 2016. © 2016 The Authors. Journal of Cellular Physiology Published by Wiley Periodicals, Inc.

Clonidine increases bone resorption in humans.

SUMMARY: Inhibition of sympathetic signaling to bone reduces bone resorption in rodents. In contrast, we show that pharmacological reduction of the sympathetic tone increases bone resorption in humans in vivo. This effect does not appear to be mediated via a direct pharmacological effect on the osteoclast. INTRODUCTION: Inhibition of sympathetic signaling to bone reduces bone resorption in rodents. It is uncertain whether a similar role for the sympathetic nervous system exists in humans. The sympathetic tone can be reduced by clonidine, which acts via alpha-2-adrenergic receptors in the brainstem. Our objective was to determine the effect of clonidine on bone turnover in humans. METHODS: The acute effect of a single oral dose of 0.3 mg clonidine on serum bone turnover markers (C-terminal cross-linking telopeptides of collagen type I (CTx), a marker for bone resorption, and procollagen type 1 N propeptide (P1NP), a marker for bone formation) was determined in a randomized crossover design in 12 healthy volunteers, aged 18-70 years. In addition, we assessed the effect of clonidine on the number of tartrate-resistant acid phosphatase-positive multinucleated cells (TRAcP(+) MNCs) and bone resorption. RESULTS: CTx concentrations increased after clonidine treatment compared to the control condition (p = 0.035). P1NP concentrations were not affected by clonidine (p = 0.520). In vitro, clonidine had no effect on the number of TRAcP(+) MNCs (p = 0.513) or on bone resorption (p = 0.996). CONCLUSIONS: We demonstrated that clonidine increases bone resorption in humans in vivo. This effect does not appear to be mediated via a direct effect on the osteoclast.

The association between low vitamin D and depressive disorders.

It has been hypothesized that hypovitaminosis D is associated with depression but epidemiological evidence is limited. We investigated the association between depressive disorders and related clinical characteristics with blood concentrations of 25-hydroxyvitamin D [25(OH)D] in a large cohort. The sample consisted of participants (aged 18-65 years) from the Netherlands Study of Depression and Anxiety (NESDA) with a current (N=1102) or remitted (N=790) depressive disorder (major depressive disorder, dysthymia) defined according to DSM-IV criteria, and healthy controls (N=494). Serum levels of 25(OH)D measured and analyzed in multivariate analyses adjusting for sociodemographics, sunlight, urbanization, lifestyle and health. Of the sample, 33.6% had deficient or insufficient serum 25(OH)D (<50 nmol l(-1)). As compared with controls, lower 25(OH)D levels were found in participants with current depression (P=0.001, Cohen's d=0.21), particularly in those with the most severe symptoms (P=0.001, Cohen's d=0.44). In currently depressed persons, 25(OH)D was inversely associated with symptom severity (ß=-0.19, s.e.=0.07, P=0.003) suggesting a dose-response gradient, and with risk (relative risk=0.90, 95% confidence interval=0.82-0.99, P=0.03) of having a depressive disorders at 2-year follow-up. This large cohort study indicates that low levels of 25(OH)D were associated to the presence and severity of depressive disorder suggesting that hypovitaminosis D may represent an underlying biological vulnerability for depression. Future studies should elucidate whether-the highly prevalent-hypovitaminosis D could be cost-effectively treated as part of preventive or treatment interventions for depression.

Longitudinal changes and seasonal variations in serum 25-hydroxyvitamin D levels in different age groups: results of the Longitudinal Aging Study Amsterdam.

UNLABELLED: Vitamin D levels remained fairly stable during ageing with increasing levels in persons aged 55-65 years old and decreasing levels in persons aged 65-88 years old. The seasonal variation was larger than the longitudinal change. Our findings implicate that vitamin D supplementation becomes more important in older age groups and during wintertime. INTRODUCTION: Longitudinal changes in serum 25-hydroxyvitamin D (25-OHD) levels during aging have not been studied extensively. Two studies showed increasing serum 25-OHD levels. One of these studies suggested that there might be decreasing levels in persons aged 65 years and older. The objectives of the current study are the following: (1) to examine longitudinal changes in serum 25-OHD levels in different age groups and (2) to describe the seasonal variation in different age groups. METHODS: Data of the Longitudinal Aging Study Amsterdam (LASA), an ongoing cohort study, were used. Two different cohorts were included: (1) younger cohort: aged 55-65 years old at baseline, n = 738, follow-up of 6 years and (2) older cohort: aged 65-88 years old at baseline, n = 1,320, follow-up of 13 years. RESULTS: At baseline, average levels were 56.5 nmol/L in the younger cohort and 51.1 nmol/L in the older cohort. In the younger cohort, a longitudinal increase in the mean serum 25-OHD levels of 4 nmol/L in 6 years was observed; in the older cohort, a longitudinal decrease in the mean serum 25-OHD levels of 4 nmol/L in 13 years was observed. The seasonal variation was ±12 nmol/L in the younger cohort and ±7 nmol/L in the older cohort. CONCLUSIONS: Long-term serum 25-OHD levels remained fairly stable during aging with slightly increasing levels in persons aged 55-65 years old and slightly decreasing levels in persons aged 65-88 years old. On average, the seasonal variation was larger than the longitudinal change. Our findings implicate that vitamin D supplementation becomes more important in older age groups and during wintertime.

Vitamin D status is associated with physical performance: the results of three independent cohorts.

UNLABELLED: This study, on the association between vitamin D status and physical performance and its decline, shows that vitamin D status is associated with physical performance in several older age groups. However, vitamin D status does not predict a decline in physical performance in individuals aged 55-65 years. INTRODUCTION: Previous research in the Longitudinal Aging Study Amsterdam (LASA) showed an association of vitamin D status with physical performance and its decline in persons aged 65 years and older. The current study aims to determine these associations in younger individuals and to replicate previous research of LASA. METHODS: Data from three independent cohorts were used: two cohorts of LASA (LASA-II with measurements in 2002 (n = 707) and 2009 (n = 491), LASA-I-2009 (n = 355)) and the baseline measurement of the B-Vitamins for the Prevention of Osteoporotic Fractures (B-PROOF) study (n = 2,813). Participants performed three tests (walking test, chair stands, and tandem stand; range total score 0-12), except in LASA-II-2002 (only walking and chair stands tests; range total score 0-8). Multiple linear and logistic regression were used to assess whether vitamin D status was associated with total physical performance and its decline, respectively. RESULTS: The mean age of the participants was 60.0 (SD 3.0), 65.9 (2.9), 78.4 (5.3), and 74.4 (6.8) years for LASA-II-2002, LASA-II-2009, LASA-I-2009, and B-PROOF, respectively. Vitamin D status was not predictive of a clinical decline in total physical performance score in the LASA-II-2002 cohort (aged 55-65 years). After adjustment for confounding, participants with serum 25(OH)D < 50 nmol/L scored 0.8 (95 % confidence interval 0.4-1.2), 0.9 (0.3-1.5), 1.5 (0.8-2.3), and 0.6 (0.3-0.9) points lower on total physical performance than participants with serum 25(OH)D ≥ 75 nmol/L. CONCLUSION: Our study confirmed that serum 25(OH)D is associated with physical performance. However, vitamin D status did not predict a clinical decline in physical performance in individuals aged 55-65 years.

No effects of n-3 fatty acid supplementation on serum total testosterone levels in older men: the Alpha Omega Trial.

The intake of the n-3 fatty acids alpha-linolenic acid (ALA), acid (EPA) and docosahexaenoic acid (DHA) has been related to testosterone levels in epidemiological analyses. The aim of this study was to assess whether the n-3 fatty acids affects testosterone levels in post-myocardial infarction (MI) patients, who are at risk of testosterone deficiency. In a double-blind, placebo-controlled trial of low-dose supplementation of n-3 fatty acids, we included 1850 male post-MI patients aged 60-80 years who participated in the Alpha Omega Trial. Patients were randomly allocated to margarines that provided 400 mg/day of EPA-DHA (n = 453), 2 mg/day of ALA (n = 467), EPA-DHA plus ALA (n = 458), or placebo (n = 472). Serum testosterone levels were assessed at baseline and after 41 months using whole day blood samples obtained at the subjects' home or at the hospital. Subjects were on average age of 68.4 (SD 5.3) years old and had baseline mean serum total testosterone of 14.8 (SD 5.6) nmol/L. The four randomized groups did not differ for baseline characteristics. ALA, EPA-DHA, and EPA-DHA plus ALA supplementation did not affect serum total testosterone compared to placebo. Moreover, n-3 fatty acid supplementation did not affect the risk of incident testosterone deficiency (n = 76 with total testosterone <8.0 nmol/L). We conclude that n-3 fatty acids supplementation did not affect serum total testosterone in men who had had a MI.

Explaining unexplained hypoglycemia: How LC-MS/MS can help.

Explaining hypoglycaemia, especially in patients without diabetes mellitus, is challenging. Here we present a case, where the added value for clinical diagnosis of insulin determination with liquid chromatography-mass spectrometry (LC-MS/MS) is shown. By the use of LC-MS/MS the different insulin analogues can be identified. The confirmation of an insulin analogue present during hypoglycaemia facilitated in our case the discussion with the patient and his family about what happened.

Performance of first-trimester combined test for Down syndrome in different maternal age groups: reason for adjustments in screening policy?

OBJECTIVE: To evaluate the performance of the first-trimester combined test (FCT) in different maternal age groups and to discuss whether adjustments in screening policies should be made. METHODS: In this retrospective study data (n = 26 274) from a fetal medicine center on FCT (maternal age, fetal NT, free ß-human chorionic gonadotrophin, pregnancy-associated plasma protein-A) were studied. RESULTS: 70.6% of cases was <36 years and 43% of the Down syndrome (DS) cases were detected in this age group. For women <36 years and advanced maternal age (AMA) women (≥36 years) detection rate (DR) and false positive rate (FPR) were 94.5% and 4.1%, and 95.8% and 13.0%, respectively (cut-off 1:200). Lowering the cut-off showed an improved balance in DR and FPR. With increasing maternal age FPR and DR increased and odds of being affected given a positive result (OAPR) decreased. CONCLUSION: FCT is effective in women <36 and ≥36 years. The balance between FPR and DR is more favourable in women <36 years with comparable OAPR. Although FPR increases with increasing maternal age, performance of FCT in AMA women is more effective than screening based on maternal age alone. Lowering the cut-off to 1:100 in AMA women is suggested to improve screening performance. Routinely offering diagnostic testing to AMA women as a screening policy for the detection of DS seems not reasonable.

First trimester screening for intra-uterine growth restriction and early-onset pre-eclampsia.

OBJECTIVE: To assess first trimester placental growth factor (PlGF) and pregnancy-associated plasma protein-A (PAPP-A) as screening markers for early-onset pre-eclampsia (PE) and intra-uterine growth restriction (IUGR). METHODS: PlGF concentration was retrospectively measured in first trimester serum specimens of 23 cases of early-onset PE (<34 weeks), 26 cases of IUGR (birth weight < 5th centile) and 5 controls per case. Levels were adjusted for gestational age (GA), ethnicity and smoking to obtain multiples of the expected median (MoM). Logistic regression was used to assess PlGF, PAPP-A and maternal characteristics as potential predictors of early-onset PE and IUGR. RESULTS: PlGF MoM levels were significantly lower in the early-onset PE group (P < 0.0001) compared with controls, but not in the IUGR group. PAPP-A MoM levels were significantly lower in the IUGR group (P < 0.01) compared with controls but not in the early-onset PE group. PlGF significantly improved the ability of systolic blood pressure at the first prenatal visit to predict early-onset PE [achieving a receiver-operating characteristics curve with area under the curve (AUC) of 0.8]. Combining systolic blood pressure at the first prenatal visit and PlGF did not significantly improve the predictive ability compared with PlGF alone (AUC = 0.83). CONCLUSION: Serum PlGF is an acceptable marker in first trimester screening for early-onset PE, but a poor marker in screening for IUGR. Screening performance of serum PAPP-A is poor for both early-onset PE and IUGR.

Falsely decreased thyroglobulin levels in a patient with differentiated thyroid carcinoma.

We describe a case of a patient with metastasized differentiated thyroid carcinoma who was treated with total thyroidectomy followed-up by radioactive iodine treatment. During treatment and follow-up the thyroglobulin levels were assayed which surprisingly did not match the clinical condition. An analytical flaw was suspected. Re-analysis in the laboratory showed the presence of a high dose hook effect (HDH), resulting in falsely low Tg levels. This case shows that HDH effects in immunoassays, like the thyroglobulin assay, still exist in daily practice. Discordance between laboratory results and clinical condition underlines the importance of short lines of communication between clinical chemists and medical doctors.

The nocturnal leopard gecko (Eublepharis macularius) uses UVb radiation for vitamin D3 synthesis.

Vitamin D is an important regulator of calcium and phosphorus homeostasis in animals. It can be acquired from the diet or synthesised de novo when skin is exposed to UVb. Vitamin D deficiency can lead to a complex of diseases collectively called metabolic bone disease (MBD). Diurnal lizards without access to UVb are prone to develop vitamin D deficiency, even when dietary vitamin D3 is provided. A trial was conducted to determine whether juvenile nocturnal lizards require access to UVb to prevent vitamin D deficiency. All leopard geckos (Eublepharis macularius) were supplemented with dietary vitamin D3. One group was exposed to low level UVb radiation (33-51 µW/cm2) from hatching until 6 months of age and a second group remained unexposed. Animals were fed ad libitum and their growth and weight gain compared with non-exposed controls. At the end of the trial, blood samples were analysed for vitamin D3 metabolites. The concentration of the vitamin D3 metabolite, 25(OH)D3, was higher in UVb exposed animals (61 ± 20 vs. 38 ± 8 nmol/L), confirming cutaneous synthesis with UVb exposure. Growth and weight gain were similar in both groups, and this, together with the absence of clinical symptoms, suggests that dietary vitamin D3 alone can meet the vitamin D requirements for growth of this nocturnal gecko, during the first six months of life. It remains to be investigated whether the higher vitamin D metabolite levels holds other health benefits for this species, such as improved bone density or immune response.

Clinical utility of bone markers in various diseases.

Measurements of bone markers (BMs) in peripheral blood or urine are a pivotal part of bone research within modern clinical medicine. In recent years the use of BMs increased substantially as they can be useful either to diagnose bone (related) disease and to follow its natural history, but also to monitor the effects of interventions. However, the use of BMs is still complicated mainly due to (pre)analytical variability of these substances, limited accessibility of assays, variable cut-off values in different countries and laboratories and heterogeneous results with regard to clinical implications of measuring BMs in several studies. This review will provide the clinician with a practical guide, based on current evidence, in which circumstances to test which bone markers for optimal diagnostic purposes, in order to improve patient care in different areas of bone diseases including Paget's disease, primary osteoporosis, tumor induced osteomalacia, hypophosphatemic rickets, van Buchem disease, chronic kidney disease, rheumatoid arthritis, neoplasma/multiple myeloma, type 2 diabetes mellitus and primary hyperparathyroidism. The clinician should consider fasting state, recent fractures, aging, menopausal status, concomitant liver and kidney disease when ordering and interpreting BM measurements as these factors might result in misleading BM concentrations. We found that BMs are clearly useful in the current diagnosis of tumor induced osteomalacia, van Buchem disease, Paget's disease and hypophosphatemic rickets. In addition, BMs are useful to monitor disease activity in chronic kidney disease, Paget's disease and are useful to monitor treatment adherence in osteoporosis.

Effects of repeated freeze-thaw cycles on endocrine parameters in plasma and serum.

Background Repeated freezing and thawing of plasma (or serum) may influence the stability of plasma (or serum) constituents. Despite the alarming warnings from commercial manuals that freeze-thaw cycles affect the stability of hormones in plasma (or serum), surprisingly little, consistent information about this concept is available in literature. Methods We studied the stability of 15 endocrine parameters (adrenocorticotropic hormone, osteocalcin, plasma renin activity, α-subunits, cortisol binding globulin, glucagon, inhibin B, fT4, TT4, TT3, rT3, TBG, TSH, chromogranin A and thyroglobulin upon repeated freeze-thaw cycles in plasma (or serum) samples from 10 volunteers. Blood was collected by venipuncture and after centrifugation and aliquoting, all samples were frozen at -20℃. Aliquots were thawed up to four times and changes in concentrations of endocrine parameters were compared to baseline condition. Results Repeated freeze-thaw cycling resulted in significant and relevant increases of plasma renin activity and a small decrease of adrenocorticotropic hormone. Conclusions For most of the analysed endocrine parameters, we found no effects of multiple freeze-thaw cycles despite alarming notifications in assay manuals. Plasma renin activity was the only endocrine parameter that showed significant and relevant changes following repeated freeze-thaw cycling.