External quality assessment-based tumor marker harmonization simulation; insights in achievable harmonization for CA 15-3 and CEA.

OBJECTIVES: CA 15-3 and CEA are tumor markers used in routine clinical care for breast cancer and colorectal cancer, among others. Current measurement procedures (MP) for these tumor markers are considered to be insufficiently harmonized. This study investigated the achievable harmonization for CA 15-3 and CEA by using an in silico simulation of external quality assessment (EQA) data from multiple EQA programs using patient-pool based samples. METHODS: CA 15-3 and CEA data from SKML (2021), UK NEQAS (2020-2021) and KEQAS (2020-2021) were used. A harmonization protocol was defined in which MPs that were considered equivalent were used to value assign EQA samples, and recalibration was only required if the MP had a bias of >5 % with value assigned EQA. Harmonization status was assessed by determining the mean level of agreement and residual variation by CV (%). RESULTS: Only MPs from Abbott, Beckman, Roche and Siemens were available in all EQA programs. For CA 15-3, recalibration was proposed for Beckman MP only and for CEA, recalibration was proposed for Siemens MP only. When the harmonization procedures were applied, for CA 15-3 the pre-harmonization mean bias range per MP was reduced from -29.28 to 9.86 %, into -0.09-0.12 % after harmonization. For CEA, the mean bias range per MP was reduced from -23.78 to 2.00 % pre-harmonization to -3.13-1.42 % post-harmonization. CONCLUSIONS: The present study suggests that a significant improvement in the harmonization status of CA 15-3 and CEA may be achieved by recalibration of a limited number of MPs.

Impact of a Public Health Emergency on Behavior, Stress, Anxiety and Glycemic Control in Patients With Pancreas or Islet Transplantation for Type 1 Diabetes.

A public health emergency such as the COVID-19 pandemic has behavioral, mental and physical implications in patients with type 1 diabetes (T1D). To what extent the presence of a transplant further increases this burden is not known. Therefore, we compared T1D patients with an islet or pancreas transplant (ß-cell Tx; n = 51) to control T1D patients (n = 272). Fear of coronavirus infection was higher in those with ß-cell Tx than without (Visual Analogue Scale 5.0 (3.0-7.0) vs. 3.0 (2.0-5.0), p = 0.004) and social isolation behavior was more stringent (45.8% vs. 14.0% reported not leaving the house, p < 0.001). A previous ß-cell Tx was the most important predictor of at-home isolation. Glycemic control worsened in patients with ß-cell Tx, but improved in control patients (ΔHbA1c +1.67 ± 8.74 vs. -1.72 ± 6.15 mmol/mol, p = 0.006; ΔTime-In-Range during continuous glucose monitoring -4.5% (-6.0%-1.5%) vs. +3.0% (-2.0%-6.0%), p = 0.038). Fewer patients with ß-cell Tx reported easier glycemic control during lockdown (10.4% vs. 22.6%, p = 0.015). All T1D patients, regardless of transplantation status, experienced stress (33.4%), anxiety (27.9%), decreased physical activity (42.0%), weight gain (40.5%), and increased insulin requirements (29.7%). In conclusion, T1D patients with ß-cell Tx are increasingly affected by a viral pandemic lockdown with higher fear of infection, more stringent social isolation behavior and deterioration of glycemic control. This trial has been registered in the clinicaltrials.gov registry under identifying number NCT05977205 (URL: https://clinicaltrials.gov/study/NCT05977205).

Investigating the Current Harmonization Status of Tumor Markers Using Global External Quality Assessment Programs: A Feasibility Study.

BACKGROUND: The harmonization status of most tumor markers (TMs) is unknown. We report a feasibility study performed to determine whether external quality assessment (EQA) programs can be used to obtain insights into the current harmonization status of the tumor markers α-fetoprotein (AFP), prostate specific antigen (PSA), carcinoembryonic antigen (CEA), cancer antigen (CA)125, CA15-3 and CA19-9. METHODS: EQA sample results provided by 6 EQA providers (INSTAND [Germany], Korean Association of External Quality Assessment Service [KEQAS, South Korea], National Center for Clinical Laboratories [NCCL, China], United Kingdom National External Quality Assessment Service [UK NEQAS, United Kingdom], Stichting Kwaliteitsbewaking Medische Laboratoriumdiagnostiek [SKML, the Netherlands], and the Royal College of Pathologists of Australasia Quality Assurance Programs [RCPAQAP, Australia]) between 2020 and 2021 were used. The consensus means, calculated from the measurement procedures present in all EQA programs (Abbott Alinity, Beckman Coulter DxI, Roche Cobas, and Siemens Atellica), was used as reference values. Per measurement procedure, the relative difference between consensus mean for each EQA sample and the mean of all patient-pool-based EQA samples were calculated and compared to minimum, desirable, and optimal allowable bias criteria based on biological variation. RESULTS: Between 19040 (CA15-3) and 25398 (PSA) individual results and 56 (PSA) to 76 (AFP) unique EQA samples were included in the final analysis. The mean differences with the consensus mean of patient-pool-based EQA samples for all measurement procedures were within the optimum bias criterion for AFP, the desirable bias for PSA, and the minimum bias criterion for CEA. However, CEA results <8 µg/L exceeded the minimum bias criterion. For CA125, CA15-3, and CA19-9, the harmonization status was outside the minimum bias criterion, with systematic differences identified. CONCLUSIONS: This study provides relevant information about the current harmonization status of 6 tumor markers. A pilot harmonization investigation for CEA, CA125, CA15-3, and CA19-9 would be desirable.

Incidence and Determinants of Spontaneous Normalization of Subclinical Hypothyroidism in Older Adults.

CONTEXT: With age, the prevalence of subclinical hypothyroidism rises. However, incidence and determinants of spontaneous normalization remain largely unknown. OBJECTIVE: To investigate incidence and determinants of spontaneous normalization of TSH levels in older adults with subclinical hypothyroidism. DESIGN: Pooled data were used from the (1) pretrial population and (2) in-trial placebo group from 2 randomized, double-blind, placebo-controlled trials (Thyroid Hormone Replacement for Untreated Older Adults With Subclinical Hypothyroidism Trial and Institute for Evidence-Based Medicine in Old Age thyroid 80-plus thyroid trial). SETTING: Community-dwelling 65+ adults with subclinical hypothyroidism from the Netherlands, Switzerland, Ireland, and the United Kingdom. PARTICIPANTS: The pretrial population (N = 2335) consisted of older adults with biochemical subclinical hypothyroidism, defined as ≥1 elevated TSH measurement (≥4.60 mIU/L) and a free T4 within the laboratory-specific reference range. Individuals with persistent subclinical hypothyroidism, defined as ≥2 elevated TSH measurements ≥3 months apart, were randomized to levothyroxine/placebo, of which the in-trial placebo group (N = 361) was included. MAIN OUTCOME MEASURES: Incidence of spontaneous normalization of TSH levels and associations between participant characteristics and normalization. RESULTS: In the pretrial phase, TSH levels normalized in 60.8% of participants in a median follow-up of 1 year. In the in-trial phase, levels normalized in 39.9% of participants after 1 year of follow-up. Younger age, female sex, lower initial TSH level, higher initial free T4 level, absence of thyroid peroxidase antibodies, and a follow-up measurement in summer were independent determinants for normalization. CONCLUSION: Because TSH levels spontaneously normalized in a large proportion of older adults with subclinical hypothyroidism (also after confirmation by repeat measurement), a third measurement may be recommended before considering treatment. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01660126 and Netherlands Trial Register, NTR3851.

Screening for thyroid dysfunction with free T4 instead of thyroid stimulating hormone (TSH) improves efficiency in older adults in primary care.

Subclinical hypothyroidism (SCHT) is defined as a consistently elevated thyroid stimulating hormone (TSH) with a free T4 (fT4) within the reference range. This diagnosis may lead to additional monitoring, levothyroxine therapy and increased patient concerns, despite lack of evidence of treatment benefit in older adults. In order to avoid this diagnosis, we evaluated the efficiency of fT4-based screening for thyroid dysfunction, in older adults in primary care and compared it with TSH-based screening. Individuals aged >65years in primary care were selected for this retrospective study when both TSH and fT4 were individually requested irrespective of the TSH value. Exclusion criteria were C-reactive protein > 10 mg/l or a history of thyroid hormone monitoring in the previous year. Screening based on fT4 instead of TSH decreased reflex testing from 23.8% to 11.2%. The positive predictive value (PPV) for clinical hypothyroidism increased from 17.3% to 52.2%. The negative predictive value was 96.1% with TSH-based screening versus 97.8% with fT4-based screening. Elevation of the TSH cutoff value from 4.2 to 6.5 mU/l resulted in a reflex test percentage of 12.5% and a PPV of 31.0%. Our results suggest that screening for thyroid dysfunction in older individuals in primary care can be improved by screening based on fT4 instead of TSH or by adjusting the TSH cutoff value. Adjustment of the screening strategy may be of interest to health policy makers because of potential cost reduction. From a patient perspective, medical concerns and unnecessary biochemical follow-up might be reduced by circumventing the diagnosis SCHT.

Familial longevity is associated with lower baseline bone turnover but not differences in bone turnover in response to rhTSH.

CONTEXT: Offspring from long-lived families have a different thyroid status than controls, characterised by higher circulating levels of thyroid stimulating hormone (TSH) and similar levels of thyroid hormone. Expression of the TSH receptor has previously been observed on various extrathyroidal tissues, including bone. However, potential physiological consequences of differences in circulating TSH as observed in familial longevity on bone tissue remain unclear. OBJECTIVE: Based on the hypothesis that TSH may inhibit bone resorption, we explored whether offspring of long-lived families have lower bone turnover than controls at baseline as well as following a challenge with recombinant human TSH (rhTSH). METHODS: Bone turnover markers CTX and P1NP were measured in fasted morning samples from 14 offspring and 12 controls at baseline and at 24 hour intervals following 0.1 mg rhTSH i.m. administration for four consecutive days. RESULTS: At baseline, mean (SEM) CTX was 0.32 (0.03) ng/ml in offspring and 0.50 (0.04) ng/ml in controls, p < 0.01, whereas mean (SEM) P1NP was 39.6 (3.2) ng/ml in offspring and 61.8 (6.6) ng/ml in controls, p < 0.01. Following rhTSH administration, both CTX and P1NP levels transiently increased over time and normalized towards baseline after 72 h (general linear modelling: CTX time p = 0.01, P1NP time p < 0.01); the response was similar between offspring and controls. CONCLUSIONS: Bone turnover markers were lower at baseline in offspring from long-lived families than in controls but increased similarly following an rhTSH challenge.

Increased stress, weight gain and less exercise in relation to glycemic control in people with type 1 and type 2 diabetes during the COVID-19 pandemic.

INTRODUCTION: Lockdown measures have a profound effect on many aspects of daily life relevant for diabetes self-management. We assessed whether lockdown measures, in the context of the COVID-19 pandemic, differentially affect perceived stress, body weight, exercise and related this to glycemic control in people with type 1 and type 2 diabetes. RESEARCH DESIGN AND METHODS: We performed a short-term observational cohort study at the Leiden University Medical Center. People with type 1 and type 2 diabetes ≥18 years were eligible to participate. Participants filled out online questionnaires, sent in blood for hemoglobin A1c (HbA1c) analysis and shared data of their flash or continuous glucose sensors. HbA1c during the lockdown was compared with the last known HbA1c before the lockdown. RESULTS: In total, 435 people were included (type 1 diabetes n=280, type 2 diabetes n=155). An increase in perceived stress and anxiety, weight gain and less exercise was observed in both groups. There was improvement in glycemic control in the group with the highest HbA1c tertile (type 1 diabetes: -0.39% (-4.3 mmol/mol) (p<0.0001 and type 2 diabetes: -0.62% (-6.8 mmol/mol) (p=0.0036). Perceived stress was associated with difficulty with glycemic control (p<0.0001). CONCLUSIONS: An increase in perceived stress and anxiety, weight gain and less exercise but no deterioration of glycemic control occurs in both people with relatively well-controlled type 1 and type 2 diabetes during short-term lockdown measures. As perceived stress showed to be associated with glycemic control, this provides opportunities for healthcare professionals to put more emphasis on psychological aspects during diabetes care consultations.

Circulating Thyroid Hormone Profile in Response to a Triiodothyronine Challenge in Familial Longevity.

CONTEXT: Familial longevity is associated with higher circulating levels of thyrotropin (TSH), in the absence of differences in circulating thyroid hormones, and a lower thyroid responsivity to TSH, as previously observed in the Leiden Longevity Study (LLS). Further mechanisms underlying these observations remain unknown. OBJECTIVE: We hypothesized that members from long-lived families (offspring) have higher thyroid hormone turnover or less negative feedback effect on TSH secretion compared to controls. METHODS: In a case-control intervention study, 14 offspring and 13 similarly aged controls received 100 µg 3,5,3'-triiodothyronine (T3) orally. Their circulating T3, free T3 (fT3), and TSH levels were measured during 5 consecutive days. We compared profiles of circulating T3, fT3, and TSH between offspring and controls using general linear modeling (GLM) and calculated the percentage decline in TSH following T3 administration. RESULTS: Circulating T3 and fT3 levels increased to supraphysiologic values and normalized over the course of 5 days. There were no serious adverse events. T3 and fT3 concentration profiles over 5 days were similar between offspring and controls (T3 GLM P = .11, fT3 GLM P = .46). TSH levels decreased in a biphasic manner and started returning to baseline by day 5. The TSH concentration profile over 5 days was similar between offspring and controls (GLM P = .08), as was the relative TSH decline (%). CONCLUSIONS: Members of long-lived families have neither higher T3 turnover nor diminished negative feedback of T3 on TSH secretion. The cause and biological role of elevated TSH levels in familial longevity remain to be elucidated.

Familial Longevity is Associated with an Attenuated Thyroidal Response to Recombinant Human Thyroid Stimulating Hormone.

CONTEXT: Longevity is associated with higher circulating levels of TSH in the absence of differences in circulating thyroid hormones (TH), as previously observed in F2 members of long-lived families (F2-LLS) and their partners (F2-Con). The mechanism underlying this observed difference remains unknown. OBJECTIVE: We hypothesized that the thyroid gland of members from long-lived families are less responsive to TSH stimulation, thereby requiring higher circulating TSH levels to maintain adequate TH levels. METHODS: We performed a case-control intervention study with a single intramuscular (gluteal) injection with 0.1 mg recombinant human TSH in a subgroup of 14 F2-LLS and 15 similarly aged F2-Con. They were followed for 4 days. No serious adverse events were reported. For analyses, we compared time trajectories of TSH and TH, and the ratio of TH to TSH using area under the curve (AUC) calculations. RESULTS: The AUC free T4/AUC TSH ratio was significantly lower in F2-LLS than in F2-Con (estimated mean [95% confidence interval] 1.6 [1.2-1.9] and 2.2 [1.9-2.6], respectively, P = 0.01). The AUC thyroglobulin/AUC TSH ratio was also lower in F2-LLS than in F2-Con (median [interquartile range] 2.1 [1.4-3.6] and 3.2 [2.7-7.4], respectively, P = 0.04). We observed the same trend with the AUC free T3/AUC TSH ratio, although the difference was not statistically significant (estimated mean [95% confidence interval] 0.6 [0.4-0.7] and 0.7 [0.6-0.8], respectively, P = 0.07). CONCLUSIONS: The present findings show that members of long-living families have a lower thyroid responsivity to TSH compared with their partners.

Men Have a Stronger Monocyte-Derived Cytokine Production Response upon Stimulation with the Gram-Negative Stimulus Lipopolysaccharide than Women: A Pooled Analysis Including 15 Study Populations.

The incidence of bacterial infections and sepsis, as well as the mortality risk from sepsis, is sex specific. These clinical findings have been attributed to sex differences in immune responsiveness. The aim of the present study was to investigate sex differences in monocyte-derived cytokine production response upon stimulation with the gram-negative stimulus lipopolysaccharide (LPS) using cytokine data from 15 study populations. Individual data on ex vivo cytokine production response upon stimulation with LPS in whole blood were available for 4,020 subjects originating from these 15 study populations, either from the general population or from patient populations with specific diseases. Men had a stronger cytokine production response than women to LPS for tumour necrosis factor-α, interleukin (IL)-6, IL-12, IL-1ß, IL-1RA, and IL-10, but not for interferon-γ. The granulocyte-macrophage colony-stimulating factor production response was lower in men than in women. These sex differences were independent of chronological age. As men had higher monocyte concentrations, we normalized the cytokine production responses for monocyte concentration. After normalization, the sex differences in cytokine production response to LPS disappeared, except for IL-10, for which the production response was lower in men than in women. A sex-based approach to interpreting immune responsiveness is crucial.

Associations of Elevated Antithyroperoxidase Antibodies with Thyroid Function, Survival, Functioning, and Depressive Symptoms in the Oldest Old: The Leiden 85-plus Study.

Background: Elevated levels of antithyroperoxidase antibodies (TPOAbs) have been associated with progression of subclinical thyroid dysfunction, extrathyroidal diseases, and decrease in functional status. However, TPOAb as determinant of future thyroid dysfunction and other clinical outcomes has not been studied well for adults aged 85 years and over. This study aimed to assess associations of TPOAb levels with thyroid function, survival, physical function, disability in activities of daily living (ADL), cognitive function, and depressive symptoms in the oldest old. Methods: Data from a population-based cohort study (Leiden 85-plus Study) of residents of Leiden, the Netherlands, aged 85 and older were used. Baseline serum TPOAb levels were available for 488 participants (82% of the total cohort). We considered levels ≥35 IU/mL as elevated. Thyroid function (thyrotropin [TSH] and free thyroxine) was assessed at age 85 (baseline), 87, and 88 years. Survival, physical function, disability in ADL, cognitive function, and depressive symptoms were assessed from age 85 through 90 years. Results: At baseline, 64 of the 85-year old participants (13.1%) had elevated TPOAb levels. They were more often female, had higher TSH levels, and a higher prevalence of overt or subclinical hypothyroidism than participants with normal TPOAb levels. Over time, elevated TPOAb levels were independently associated with a lower mortality risk (hazard ratio 0.72, [95% confidence interval 0.53-0.99]), but were not associated with changes in thyroid function, nor with physical function, disability in ADL, cognitive function, or depressive symptoms. Conclusions: In community-dwelling oldest old, elevated TPOAb levels are cross-sectionally associated with higher TSH levels. Over time, elevated TPOAb levels are associated with a survival benefit but are not associated with changes in thyroid function, functional status, or depressive symptoms in old age. The added clinical value of TPOAb tests in oldest old persons with thyroid dysfunction is limited.

Endogenous sex hormones and risk of venous thromboembolism in young women.

BACKGROUND: The risk of venous thromboembolism (VTE) in young women can predominantly be attributed to exogenous hormone use. The influence of (abnormalities in) endogenous sex hormones, as in polycystic ovary syndrome (PCOS) or primary ovarian insufficiency (POI), on VTE risk is uncertain. OBJECTIVES: Th assess the association between endogenous sex hormone levels and VTE risk. METHODS: Women aged ≤45 years from the MEGA case-control study who provided a blood sample in the absence of exogenous hormone exposure or pregnancy were included. Sex hormone-binding globulin (SHBG), estradiol, follicle-stimulating hormone (FSH) and testosterone were measured. The free androgen index (FAI) and estradiol to testosterone ratio (E:T) were calculated. VTE risk was assessed according to quartiles (Qs) of levels and clinical cut-offs as proxies for PCOS (FAI > 4.5) and POI (FSH > 40 U/L). Logistic regression models were used to estimate adjusted odds ratios (ORs) with 95% confidence intervals (CIs). RESULTS: Six hundred and sixty-five women (369 cases; 296 controls) were eligible for the analyses. Testosterone and FSH levels, E:T and POI (FSH > 40 U/L vs FSH ≤ 40 U/L) were not associated with VTE risk. For estradiol, VTE risk was increased with levels in Q4 vs Q1 (OR 1.6; 95% CI 1.0-2.5). There was a dose-response relationship between SHBG levels and VTE risk, with the highest OR at Q4 vs Q1: 2.0 (95% CI 1.2-3.3). FAI > 4.5 (PCOS proxy) vs FAI ≤ 4.5 was associated with increased VTE risk (OR 3.3; 95% CI 0.9-11.8). CONCLUSIONS: Estradiol, SHBG and FAI were associated with VTE risk, suggesting a role for endogenous sex hormones in the pathophysiology of VTE in young women.

Increased cardiovascular disease risk in women with a history of recurrent miscarriage.

INTRODUCTION: Cardiovascular disease is the leading cause of death in women. Observational studies suggest that women with a history of recurrent miscarriage have an increased risk of cardiovascular disease. MATERIAL AND METHODS: Women who visited the recurrent miscarriage clinic at Leiden University Medical Center between 2000 and 2010 and who had their third consecutive miscarriage before the age of 31 years, were invited to participate in this follow-up study (between 2012 and 2014). The reference group consisted of women with at least one uncomplicated pregnancy and no miscarriage, matched by zip code, age, and date of pregnancy. All women were invited for risk factor screening, including physical examination and blood collection. Main outcome measures were the (extrapolated) 10- and 30-year cardiovascular risk scores using the Framingham risk score. A subanalysis was performed for women with idiopathic recurrent miscarriage. RESULTS: Thirty-six women were included in both groups. Mean follow up was 7.5 years. Women with recurrent miscarriage had a significantly higher extrapolated 10-year cardiovascular risk score (mean 6.24%, SD 5.44) compared with women with no miscarriage (mean 3.56%, SD 1.82, P = .007) and a significantly higher 30-year cardiovascular risk score (mean 9.86%, SD 9.10) compared with women with no miscarriage (mean 6.39%, SD 4.20, P = .04). Similar results were found in women with idiopathic recurrent miscarriage (n = 28). CONCLUSIONS: Women with a history of recurrent miscarriage differ in cardiovascular risk profile at a young age compared with women with no miscarriage. The findings support an opportunity to identify women at risk of cardiovascular disease later in life and a possible moment for intervention.

Determinants of Advanced Bone Age in Childhood Obesity
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BACKGROUND: Childhood obesity is associated with advanced bone age (BA). Previous studies suggest that androgens, oestrogens, sex hormone-binding globulin, and insulin are responsible for this phenomenon, but results are contradictory and might be biased by confounders. We aim to elucidate this matter by applying a multivariate approach. METHOD: We performed a correlation analysis of BA standard deviation score (SDS) with age- and sex-specific SDS for androgens, oestrogens, and with indicators of insulin secretion derived from oral glucose tolerance testing, in a group of obese children. A multivariate analysis was performed to investigate which parameters were independently predictive of BA SDS. RESULTS: In this cohort (n = 101; mean age 10.9 years; mean BA 11.8 years; mean BMI SDS 3.3), BMI SDS was significantly correlated to BA SDS (r = 0.55, p < 0.001). In a regression analysis in the total cohort (B = 0.27, p < 0.001) as well as in females (B = 0.34, p = 0.042), males (B = 0.31, p = 0.006), and pubertal children (B = 0.32, p = 0.046), dehydroepiandrosterone sulphate (DHEAS) showed a positive, independent association with BA SDS. No association with indicators of insulin secretion was found. CONCLUSION: BMI SDS is highly correlated to BA SDS in obese children. Increased DHEAS has a central role in advanced BA in obese children.
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Familial Longevity Is Not Associated with Major Differences in the Hypothalamic-Pituitary-Gonadal Axis in Healthy Middle-Aged Men.

CONTEXT: A trade-off between fertility and longevity possibly exists. The association of the male hypothalamic-pituitary-gonadal (HPG) axis with familial longevity has not yet been investigated. OBJECTIVE: To study 24-h hormone concentration profiles of the HPG axis in men enriched for familial longevity and controls. DESIGN: We frequently sampled blood over 24 h in 10 healthy middle-aged male offspring of nonagenarian participants from the Leiden Longevity Study together with 10 male age-matched controls. Individual 24-h luteinizing hormone (LH) and testosterone concentration profiles were analyzed by deconvolution analyses to estimate secretion parameters. Furthermore, the temporal relationship between LH and testosterone was assessed by cross-correlation analysis. We used (cross-)approximate entropy to quantify the strength of feedback and/or feedforward control of LH and testosterone secretion. RESULTS: Mean [95% confidence interval (CI)] total LH secretion of the offspring was 212 (156-268) U/L/24 h, which did not differ significantly (p = 0.51) from the total LH secretion of controls [186 (130-242) U/L/24 h]. Likewise, mean (95% CI) total testosterone secretion of the offspring [806 (671-941) nmol/L/24 h] and controls [811 (676-947) nmol/L/24 h] were similar (p = 0.95). Other parameters of LH and testosterone secretion were also not significantly different between offspring and controls. The temporal relationship between LH and testosterone and the strength of feedforward/feedback regulation within the HPG axis were similar between offspring of long-lived families and controls. CONCLUSION: This relatively small study suggests that in healthy male middle-aged participants, familial longevity is not associated with major differences in the HPG axis. Selection on both fertility and health may in part explain the results.

Growth hormone secretion is diminished and tightly controlled in humans enriched for familial longevity.

Reduced growth hormone (GH) signaling has been consistently associated with increased health and lifespan in various mouse models. Here, we assessed GH secretion and its control in relation with human familial longevity. We frequently sampled blood over 24 h in 19 middle-aged offspring of long-living families from the Leiden Longevity Study together with 18 of their partners as controls. Circulating GH concentrations were measured every 10 min and insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP3) every 4 h. Using deconvolution analysis, we found that 24-h total GH secretion was 28% lower (P = 0.04) in offspring [172 (128-216) mU L-1 ] compared with controls [238 (193-284) mU L-1 ]. We used approximate entropy (ApEn) to quantify the strength of feedback/feedforward control of GH secretion. ApEn was lower (P = 0.001) in offspring [0.45 (0.39-0.53)] compared with controls [0.66 (0.56-0.77)], indicating tighter control of GH secretion. No significant differences were observed in circulating levels of IGF-1 and IGFBP3 between offspring and controls. In conclusion, GH secretion in human familial longevity is characterized by diminished secretion rate and more tight control. These data imply that the highly conserved GH signaling pathway, which has been linked to longevity in animal models, is also associated with human longevity.

Pituitary Hormone Secretion Profiles in IGSF1 Deficiency Syndrome.

BACKGROUND: Loss-of-function mutations in immunoglobulin superfamily member 1 (IGSF1) cause an X-linked syndrome of central hypothyroidism, macroorchidism, delayed pubertal testosterone rise, variable prolactin deficiency and variable partial GH deficiency in childhood. The clinical features and gene expression pattern suggest a pivotal role for IGSF1 in the pituitary, but detailed knowledge on pituitary hormone secretion in this syndrome is lacking. We therefore aimed to study the 24-hour pituitary hormone secretion in male patients with IGSF1 deficiency. METHODS: We collected blood samples every 10 min for 24 h in eight adult male IGSF1-deficient patients and measured circulating TSH, prolactin and gonadotropins. Deconvolution, modified cosinor and approximate entropy analyses were applied to quantify secretion rates, diurnal rhythmicity and regularity of hormone release. Results were compared to healthy controls matched for age and body mass index. RESULTS: Compared to healthy controls, IGSF1-deficient patients showed decreased pulsatile secretion of TSH with decreased disorderliness and reduced diurnal variation. Basal and pulsatile secretion of FSH was increased by over 200%, while LH secretion did not differ from healthy controls. We observed a bimodal distribution of prolactin secretion, i.e. severe deficiency in three and increased basal and total secretion in the other five patients. CONCLUSION: The altered TSH secretion pattern is consistent with the previously hypothesized defect in thyrotropin-releasing hormone signaling in IGSF1 deficiency. However, the phenotype is more extensive and includes increased FSH secretion without altered LH secretion as well as either undetectable or increased prolactin secretion.

Accuracy of Continuous Glucose Monitoring Measurements in Normo-Glycemic Individuals.

BACKGROUND: The validity of continuous glucose monitoring (CGM) is well established in diabetic patients. CGM is also increasingly used for research purposes in normo-glycemic individuals, but the CGM validity in such individuals is unknown. We studied the accuracy of CGM measurements in normo-glycemic individuals by comparing CGM-derived versus venous blood-derived glucose levels and measures of glycemia and glycemic variability. METHODS: In 34 healthy participants (mean age 65.7 years), glucose was simultaneously measured every 10 minutes, via both an Enlite® CGM sensor, and in venous blood sampled over a 24-hour period. Validity of CGM-derived individual glucose measurements, calculated measures of glycemia over daytime (09:00h-23:00h) and nighttime (23:00h-09:00h), and calculated measures of glycemic variability (e.g. 24h standard deviation [SD]) were assessed by Pearson correlation coefficients, mean absolute relative difference (MARD) and paired t-tests. RESULTS: The median correlation coefficient between CGM and venous glucose measurements per participant was 0.68 (interquartile range: 0.40-0.78), and the MARD was 17.6% (SD = 17%). Compared with venous sampling, the calculated measure of glycemia during daytime was 0.22 mmol/L higher when derived from CGM, but no difference was observed during nighttime. Most measures of glycemic variability were lower with CGM than with venous blood sampling (e.g., 24h SD: 1.07 with CGM and 1.26 with venous blood; p-value = 0.004). CONCLUSION: In normo-glycemic individuals, CGM-derived glucose measurements had good agreement with venous glucose levels. However, the measure of glycemia was higher during the day and most measures of glycemic variability were lower when derived from CGM.