Age-Specific Reference Intervals for Thyroid-Stimulating Hormones and Free Thyroxine to Optimize Diagnosis of Thyroid Disease.

Background: Thyroid-stimulating hormone (TSH) and subsequent free thyroxine (FT4) concentrations outside the reference interval (RI) are used to diagnose thyroid diseases. Most laboratories do not provide age-specific RIs for TSH and FT4 beyond childhood, although TSH concentrations vary with age. Therefore, we aimed to establish TSH and FT4 age-specific RIs throughout life and aimed to determine whether using these RIs would result in reclassification of thyroid disease diagnoses in adults. Methods: This multicenter retrospective cross-sectional study used big data to determine indirect RIs for TSH and FT4. These RIs were determined by TMC and refineR-analysis, respectively, using four different immunoassay platforms (Roche, Abbott, Siemens, and Beckman Coulter). Retrospective data (2008-2022) from 13 Dutch laboratories for general practitioners and local hospitals were used. RIs were evaluated per manufacturer. Age groups were established from 2 to 20 years by 2-year categories and decade categories between 20 and 100 years. Results: We included totally 7.6 million TSH and 2.2 million FT4 requests. TSH upper reference limits (URLs) and FT4 lower reference limits were higher in early childhood and decreased toward adulthood. In adulthood, TSH URLs increased from 60 years in men, and from 50 years in women, while FT4 URLs increased from 70 years onward. Using adult age-specific RIs resulted in a decrease in diagnoses of subclinical and overt hypothyroidism in women above 50 and men above 60 years in our Roche dataset. Conclusion: This study stressed the known importance of using age-specific RIs for TSH and FT4 in children. This study also showed the clinical relevance of using age-specific RIs for TSH in adulthood to reduce diagnoses of subclinical hypothyroidism in older persons. Therefore, implementation of adult TSH age-specific RIs should be strongly considered. Data are less uniform regarding FT4 age-specific RIs and more research should be performed before implementing these in clinical practice.

Leptin, ghrelin and high-molecular-weight adiponectin in relation to anxiety in older adults.

BACKGROUND: Leptin and ghrelin have been linked to depressive symptoms in older adults. There is a large overlap between depression and anxiety in this group. It is unclear whether the same associations exist with anxiety. Adiponectin has an inverse association with anxiety in older adults. However, the association between the most biologically active isoform - high-molecular-weight (HMW) adiponectin - and anxiety has not been previously reported. METHODS: We analyzed the association between leptin, ghrelin and HMW adiponectin and general symptoms of anxiety (HADS-A score ≥ 7) at baseline and after three years of follow-up in a population based cohort of older adults in the Netherlands (n = 898) using multivariable logistic regression analyses. RESULTS: For leptin there was significant effect modification by sex. We found a positive association between leptin and general symptoms of anxiety in men at baseline and after three years of follow-up after adjusting for depressive symptoms, when comparing the third to the first leptin tertile (T3 vs T1 OR 3.40, 95 % CI 1.08 - 10.78). We found no significant associations for ghrelin. HMW adiponectin was associated with general symptoms of anxiety at follow up. We found a positive association both before and after adjustment for depressive symptoms (T3 vs T1 OR 3.26, 95 % CI 1.36 - 7.83). CONCLUSIONS: Our results showed significant associations in men only between leptin and HMW adiponectin and general symptoms of anxiety after three years of follow up. Our findings contribute to further insight into the pathophysiology of anxiety in older adults. However, further research is necessary as we show associations.

The association between low sex hormone binding globulin and increased risk of type 2 diabetes is mediated by increased visceral and liver fat: results from observational and Mendelian randomization analyses.

The aim of this study was to investigate the associations between sex hormone binding globulin (SHBG), visceral fat (VAT), liver fat content, and risk of type 2 diabetes. In the Netherlands Epidemiology of Obesity study 5690 women (53%) and men without pre-existing diabetes were included and followed for incident type 2 diabetes. SHBG concentrations were measured in all, VAT with MRI, and liver fat content with proton-MR spectroscopy in n=1822. We examined associations between SHBG and liver fat with linear regression and bidirectional Mendelian randomization analyses, and between SHBG and type 2 diabetes with Cox regression adjusted for confounding, and additionally for VAT and liver fat to examine mediation. The mean(SD) age was 56(6) years, BMI 30(4) kg/m2, median(IQR) SHBG was 47 (34,65) nmol/L in women and 34 (26,43) nmol/L in men, median(IQR) liver fat was 3.4(1.6,8.2)% in women and 6.0 (2.9,13.5)% in men. Compared with the highest SHBG quartile, liver fat was 2.9-fold (95%CI: 2.4,3.4) increased in women and 1.6-fold (95%CI: 1.3,1.8) in men, and the hazard ratio (95%CI) of type 2 diabetes was 4.9 (2.4,9.9) in women and 1.8 (1.1,2.9) in men. Genetically predicted SHBG was associated with liver fat content (women: SD (95%CI) -0.45(-0.55,-0.35), men: ln(95%CI) -0.25 (-0.34,-0.16)). VAT and liver fat together mediated 43% (women) and 60% (men) of the SHBG-type 2 diabetes association. To conclude, in a middle-aged population with overweight, the association between low SHBG and increased risk of type 2 diabetes was for a large part mediated by increased VAT and liver fat.

Addition of testosterone to endocrine care for transgender women: a dose-finding and feasibility trial.

OBJECTIVE: Transgender women who underwent gonadectomy have lower serum testosterone concentrations than cisgender women. There is uncertainty regarding the dosing and side effects of supplementation of testosterone in transgender women. This study aimed to assess the feasibility of dosing testosterone to the cisgender female physiological range in transgender women. In addition, we explored changes in cardiovascular parameters, virilizing side effects, and clinical symptoms. DESIGN: This is an open-label, single-arm feasibility study. Participants initially went through a dose-titration phase with 2-week intervals of 0.07-0.09-0.13 mL (277-318-403 µg bioavailable testosterone) testosterone 2% gel to establish a dose leading to serum testosterone concentrations between 1.5 and 2.5 nmol/L. This dose was then continued for 8 weeks. METHODS: Participants applied daily transdermal testosterone 2% gel (Tostran®) at the prescribed dosage. Testosterone was measured every 2-4 weeks. Laboratory analyses, side effects, and clinical symptoms were evaluated. RESULTS: In total, 12 participants were included. Most participants required a dose of 0.07 mL (277 µg bioavailable testosterone) or 0.09 mL (318 µg bioavailable testosterone) to reach serum testosterone concentrations of 1.5-2.5 nmol/L. Continuing this dose, testosterone concentrations remained stable throughout the study. Changes in clinical outcomes were in the desired direction, and side effects were mild. CONCLUSIONS: The use of testosterone supplementation in transgender women seems feasible and safe in the short term. Although dosing requires personalized titration, stable testosterone levels can be established. A blinded, placebo-controlled, randomized clinical trial is needed to study the clinical benefit.

Stability of steroid hormones in dried blood spots (DBS).

OBJECTIVES: Steroid hormone levels of patients may be monitored via dried blood spot (DBS) sampling at home. Stability of steroid hormones in DBS samples, however, needs to be established. METHODS: DBS samples from healthy volunteers were collected and stored at various temperatures. Steroid hormone concentrations in DBS were measured directly, at day 2, day 7 and day 14 following storage at 37 °C and after 7 days, 14 days, 3 months and 6 months following storage at -20 °C, 4 °C and room temperature (RT). Cortisol, cortisone, corticosterone, testosterone, androstenedione, and 17-hydroxyprogesterone (17-OHP) were assessed using LC-MS/MS. RESULTS: All steroids were stable (±15 %) up to 14 days when stored at 37 °C, except for cortisone (only stable until 2 days). All steroids were stable up to 6 months when stored at -20 °C, 4 °C and RT. However, there were some exceptions, for androstenedione at RT (only stable until 7 days), for 17-OHP when stored at -20 °C (only stable until 3 months), for cortisone at RT and 4 °C (only stable until 14 days), and cortisol at RT (only stable until 3 months). CONCLUSIONS: Overall, we demonstrated stability of steroid hormone concentrations in DBS under various conditions which may be encountered during shipping to the diagnostic laboratory and during long-term storage before analysis.

Development of an algorithm combining blood-based biomarkers, fecal immunochemical test, and age for population-based colorectal cancer screening.

BACKGROUND AND AIMS: Implementation of screening modalities have reduced the burden of colorectal cancer (CRC), but high false positive rates pose a major problem for colonoscopy capacity. We aimed to create a tailored screening algorithm that expands the fecal immunochemical test (FIT) with a blood specimen and current age to improve selection of individuals for diagnostic colonoscopy. METHODS: In this prospective multicenter study, 8 blood-based biomarkers (carcinoembryonic antigen, ferritin, high-sensitivity C-reactive protein, human epididymis protein 4, Cyfra21-1, hepsin, interleukin 8, and osteoprotegerin) were investigated in 1977 FIT-positive individuals from the Danish national CRC screening program undergoing follow-up colonoscopy. Specimens were analyzed on Architect i2000, Architect c8000 (both from Abbott, Chicago, IL, USA), or Luminex xMAP machines (MilliporeSigma, St. Louis, Mo, USA). FIT analyses and blood-based biomarker data were combined with clinical data (ie, age and colonoscopy findings) in a cross-validated logistic regression model (algorithm) benchmarked against a model solely using the FIT result (FIT model) applying different cutoffs for FIT positivity. RESULTS: The cohort included individuals with CRC (n = 240), adenomas (n = 938), or no neoplastic lesions (n = 799). The cross-validated algorithm combining the 8 biomarkers, quantitative FIT result, and age performed superior to the FIT model in discriminating CRC versus non-CRC individuals (area under the receiver operating characteristic curve, 0.77 vs 0.67, respectively; P < .001). When discriminating individuals with either CRC or high- or medium-risk adenomas versus low-risk adenomas or clean colorectum, the areas under the receiver operating characteristic curve were 0.68 versus 0.64 for the algorithm and FIT model, respectively. CONCLUSIONS: The algorithm presented here can improve patient allocation to colonoscopy, reducing colonoscopy burden without compromising cancer and adenoma detection rates or vice versa.

A systematic review of subclinical hyperthyroidism guidelines: a remarkable range of recommendations.

Background: Subclinical thyroid diseases are often the subject of debate concerning their clinical significance, the appropriateness of diagnostic testing, and possible treatment. This systematic review addresses the variation in international guidelines for subclinical hyperthyroidism, focusing on diagnostic workup, treatment, and follow-up recommendations. Methods: Following the PRISMA guidelines, we searched PubMed, Embase, and guideline-specific databases and included clinical practice guidelines with recommendations on subclinical hyperthyroidism. Guideline recommendations were extracted, and quality assessment was performed using selected questions of the Appraisal of Guidelines for Research & Evaluation (AGREE) II instrument. Results: Of the 2624 records screened, 22 guidelines were included, which were published between 2007 and 2021. Guideline quality was generally intermediate to low. Diagnostic approaches differed substantially, particularly in the extent of recommended testing. Treatment initiation depended on TSH levels, age, and comorbidities, but the level of detail regarding defining precise comorbidities varied. Recommendations for monitoring intervals for follow-up ranged from 3 to 12 months. Conclusion: This review underscores the existing variability in (inter)national guidelines concerning subclinical hyperthyroidism. There isa need for clear recommendations in guidelines considering diagnostic workup, treatment, and follow-up of subclinical hyperthyroidism. In order to establish this, future research should focus on determining clear and evidence-based intervention thresholds.

Vitamin D: Analytical Advances, Clinical Impact, and Ongoing Debates on Health Perspectives.

BACKGROUND: Vitamin D, acknowledged since the 1930s for its role in preventing rickets, gained additional prominence in relation to fragility fracture prevention in the late 1980s. From the early 2000s, connections between vitamin D deficiency and extra-skeletal pathologies emerged, alongside increased awareness of widespread deficits. This prompted crucial debates on optimal serum concentrations, expected to conclude when the outcomes of high-dose supplementation randomized controlled trials were available. Skepticism arose with inconclusive results from these trials. CONTENT: This review begins with an exploration of vitamin D metabolism, followed by a detailed description of the measurement of vitamin D metabolites and the crucial role of standardization. Subsequent sections focus on the association of vitamin D with bone health and explore the extra-skeletal effects. The review concludes with a comprehensive discussion on the definition of vitamin D status and its implications for supplementation. SUMMARY: Despite standardization efforts, assay variations and challenges still exist, especially in specific patient groups. Vitamin D supplementation has a significant impact on bone metabolism and optimal vitamin D status improves the efficacy of antiresorptive drugs such as bisphosphonates. The extra-skeletal effects of vitamin D remain debated, but may include potential benefits in conditions such as respiratory infections and cancer mortality, particularly in deficient individuals. The definition of vitamin D sufficiency is nuanced, especially when variations in population groups and analytical methods are taken into account. Despite ongoing debates and recent mega-trials tempering enthusiasm, vitamin D remains a complex and essential element in human health. Further research is needed to clarify its role in various health outcomes and guide supplementation strategies.

Vitamin D Metabolites Before and After Kidney Transplantation in Patients Who Are Anephric.

RATIONALE & OBJECTIVE: Kidneys are vital for vitamin D metabolism, and disruptions in both production and catabolism occur in chronic kidney disease. Although vitamin D activation occurs in numerous tissues, the kidneys are the most relevant source of circulating active vitamin D. This study investigates extrarenal vitamin D activation and the impact of kidney transplantation on vitamin D metabolism in patients who are anephric. STUDY DESIGN: Case series. SETTING & PARTICIPANTS: Adult patients with previous bilateral nephrectomy (anephric) not receiving active vitamin D therapy evaluated at the time of (N=38) and 1 year after (n=25) kidney transplantation. ANALYTICAL APPROACH: Chromatography with tandem mass spectrometry was used to measure vitamin D metabolites. Activity of CYP24A1 [24,25(OH)2D/25(OH)D] and CYP27B1 [1α,25(OH)2D/25(OH)D] is expressed as metabolic ratios. Differences between time points were evaluated by paired t-test or Wilcoxon matched-pairs signed-rank test. RESULTS: At time of transplantation, 1α,25(OH)2D was detectable in all patients (4-36pg/mL). There was a linear relationship between 25(OH)D and 1α,25(OH)2D levels (r=0.58, P<0.001), with 25(OH)D explaining 34% of the variation in 1α,25(OH)2D levels. There were no associations between 1α,25(OH)2D and biointact parathyroid hormone (PTH) or fibroblast growth factor 23 (FGF-23). One year after transplantation, 1α,25(OH)2D levels recovered (+205%), and CYP27B1 activity increased (+352%). Measures of vitamin D catabolism, 24,25(OH)2D and CYP24A1 activity increased 3- to 5-fold. Also, at 12 months after transplantation, 1α,25(OH)2D was positively correlated with PTH (ρ=0.603, P=0.04) but not with levels of 25(OH)D or FGF-23. LIMITATIONS: Retrospective, observational study design with a small cohort size. CONCLUSIONS: Low-normal levels of 1α,25(OH)2D was demonstrated in anephric patients, indicating production outside the kidneys. This extrarenal CYP27B1 activity may be more substrate driven than hormonally regulated. Kidney transplantation seems to restore kidney CYP27B1 and CYP24A1 activity, as evaluated by vitamin D metabolic ratios, resulting in both increased vitamin D production and catabolism. These findings may have implications for vitamin D supplementation strategies in the setting of kidney failure and transplantation. PLAIN-LANGUAGE SUMMARY: Vitamin D activation occurs in multiple tissues, but the kidneys are considered the only relevant source of circulating levels. This study investigates vitamin D activation outside the kidneys by measuring vitamin D metabolites in 38 patients without kidneys. Active vitamin D was detectable in all patients, indicating production outside of the kidneys. There was a strong relationship between active and precursor vitamin D levels, but no association with mineral metabolism hormones, indicating that vitamin D production was more substrate dependent than hormonally regulated. One year after kidney transplantation, active vitamin D levels increased 2-fold and breakdown products increased 3-fold, indicating that production and degradation of the hormone recovers after kidney transplantation. These findings are relevant for future research into vitamin D supplementation in kidney failure.

Analysis of Serum Free Thyroxine Concentrations in Healthy Term Neonates Underlines Need for Local and Laboratory-Specific Reference Interval: A Systematic Review and Meta-Analysis of Individual Participant Data.

Background: Initial evaluation of the hypothalamus-pituitary-thyroid axis is done by measuring serum free thyroxine (fT4) and thyrotropin concentrations. For correct interpretation of these measurements, reliable age-specific reference intervals (RIs) are fundamental. Since neonatal fT4 RIs conforming to the Clinical and Laboratory Standards Institute guidelines are not available for all assays, we set out to create literature-based uniform age-specific neonatal fT4 RIs that may be used for every assay. Methods: For meta-analysis of individual participant fT4 concentrations, we systematically searched MEDLINE and Embase (search date December 6, 2023; PROSPERO registration CRD42016041871). We searched for studies reporting fT4 concentrations in healthy term newborns aged 2-27 days, born to mothers without thyroid disease in iodine-sufficient regions. Authors were invited to supply data. Due to standardization differences between assays, data could not be combined for meta-analysis directly, and we attempted to normalize the data using two distinct methods. Results: We obtained 4206 fT4 concentrations from 20 studies that used 13 different assays from 6 manufacturers. First, we set out to normalize fT4 data using the mean and standard deviation of (assay-specific) adult RIs. fT4 concentrations were transformed into Z-scores, assuming a normal distribution. Using a linear mixed-effects model (LMM), we still found a significant difference between fT4 concentration across studies (p < 0.001), after this normalization. As a second approach, we normalized the fT4 concentrations using data from a method/assay comparison study. We used the relationship between the Cobas assay and the other assays as a reference point to convert all values to Cobas values. However, this method also failed to produce consistent results, with significant differences between the normalized data (LMM p < 0.001). Conclusions: We conclude that our attempts at normalizing fT4 assay results were unsuccessful. Confounders related to our unsuccessful analysis may be assay related and/or biological. These findings have significant implications for patient care, since relying on RIs from literature may result in erroneous interpretation of results. Therefore, we strongly recommend to establish local RIs for accurate interpretation of serum fT4 concentrations in neonates.