Post-pituitary surgery copeptin analysis as a 'rule-out' test for post-operative diabetes insipidus.

BACKGROUND: Diabetes insipidus (DI) is a recognised complication of pituitary surgery, with diagnosis requiring clinical observation aided by plasma and urine electrolytes and osmolalities. Copeptin is a stable surrogate marker of AVP release and has potential to facilitate prompt diagnosis of post-operative DI. This assay has been shown to accurately predict which patients are likely to develop DI following pituitary surgery. OBJECTIVE: To determine whether copeptin analysis can be used to predict which patients are at risk of developing DI following trans-sphenoidal surgery (TSS). METHODS: Seventy-eight patients undergoing TSS had samples taken for copeptin pre-operatively and at day 1 post-TSS. The majority of patients also had samples from day 2, day 8, and week 6 post-TSS. Results from patients who developed post-operative DI (based on clinical assessment, urine and plasma biochemistry and the need for treatment with DDAVP) were compared to those who did not. Patients with any evidence of pre-operative DI were excluded. RESULTS: Of 78 patients assessed, 11 were clinically determined to have developed DI. Differences were observed between patients with DI and those without in post-operative samples. Of note, there was a significant difference in plasma copeptin at day 1 post-operation (p = 0.010 on Kruskal-Wallis test), with copeptin levels greater than 3.4 pmol/l helping to rule out DI (91% sensitivity, 55% specificity at this cut off). CONCLUSION: In the post-TSS setting, copeptin is a useful rule-out test in patients with values above a defined threshold, which may facilitate earlier decision making and shorter hospital stays.

Protocol for an observational study investigating hormones triggering the onset of sustained lactation: the INSIGHT study.

INTRODUCTION: Lactation is a hormonally controlled process that promotes infant growth and neurodevelopment and reduces the long-term maternal risk of diabetes, cardiovascular disease and breast cancer. Hormones, such as prolactin and progesterone, mediate mammary development during pregnancy and are critical for initiating copious milk secretion within 24-72 hours post partum. However, the hormone concentrations mediating lactation onset are ill defined. METHODS AND ANALYSIS: The primary objective of the investigating hormones triggering the onset of sustained lactation study is to establish reference intervals for the circulating hormone concentrations initiating postpartum milk secretion. The study will also assess how maternal factors such as parity, pregnancy comorbidities and complications during labour and delivery, which are known to delay lactation, may affect hormone concentrations. This single-centre observational study will recruit up to 1068 pregnant women over a 3-year period. A baseline blood sample will be obtained at 36 weeks' gestation. Participants will be monitored during postpartum days 1-4. Lactation onset will be reported using a validated breast fullness scale. Blood samples will be collected before and after a breastfeed on up to two occasions per day during postpartum days 1-4. Colostrum, milk and spot urine samples will be obtained on a single occasion. Serum hormone reference intervals will be calculated as mean±1.96 SD, with 90% CIs determined for the upper and lower reference limits. Differences in hormone values between healthy breastfeeding women and those at risk of delayed onset of lactation will be assessed by repeated measures two-way analysis of variance or a mixed linear model. Correlations between serum hormone concentrations and milk composition and volume will provide insights into the endocrine regulation of milk synthesis. ETHICS AND DISSEMINATION: Approval for this study had been granted by the East of England-Cambridgeshire and Hertfordshire Research Ethics Committee (REC No. 20/EE/0172), by the Health Research Authority (HRA), and by the Oxford University Hospitals National Health Service Foundation Trust. The findings will be published in high-ranking journals and presented at national and international conferences. TRIAL REGISTRATION NUMBER: ISRCTN12667795.

The potential for utilising in-hospital glucose measurements to detect individuals at high risk of previously undiagnosed diabetes: Retrospective cohort study.

BACKGROUND: Many people with undiagnosed diabetes have hyperglycaemia when admitted to hospital. Inpatient hyperglycaemia can be an indication of diabetes mellitus but can also indicate a stress response. This study reports the extent to which an in-hospital maximum observed random glucose measurement is an indicator of the need for in-hospital (or subsequent) HbA1c measurement to look for undiagnosed diabetes. METHODS: Blood glucose, HbA1c, age and sex were collected for all adults following admission to a UK NHS trust hospital from 1 January 2019 to 31 December 2020. We restricted the analysis to those participants who were registered with a GP practice that uses the trust laboratory and who had at least some tests requested by those practices since 2008. We stratified individuals according to their maximum in-hospital glucose measurement and report the number of these with HbA1c measurement ≥48 mmol/mol (6.5%) prior to the index admission, and during and after admission. We calculated an estimated proportion of individuals in each blood glucose stratum without a follow-up HbA1c who could have undiagnosed diabetes. RESULTS: In toal, 764,241 glucose measurements were recorded for 81,763 individuals who were admitted to the Oxford University Hospitals Trust. The median (Q1, Q3) age was 70 (56, 81) years, and 53% were males. Of the population, 70.7% of individuals declared themselves to be of White ethnicity, 3.1% of Asian background, and 1.1% of Black background, with 23.1% unstated. Of those individuals, 22,375 (27.4%) had no previous HbA1c measurement recorded. A total of 1689 individuals had a diabetes-range HbA1c during or after their hospital admission (2.5%) while we estimate an additional 1496 (2.2%) may have undiagnosed diabetes, with the greatest proportion of these having an in-hospital glucose of ≥15 mmol/L. We estimate that the number needed to detect a possible new case of diabetes falls from 16 (in-hospital glucose 8 mmol/L to <9 mmol/L) to 4 (14 mmol/L to <15 mmol/L). CONCLUSION: The number of people who need to be tested to identify an individual who may have diabetes decreases as a testing threshold based on maximum in-hospital glucose concentration increases. Among those with hyperglycaemia and no previous HbA1c measurement in the diabetes range, there appears to be a lack of subsequent HbA1c measurement. This work identifies the potential for integrating the testing and follow-up of people, with apparently unrecognised hospital hyperglycaemia across primary and secondary care.

Combined statistical decision limits based on two GH-2000 scores for the detection of growth hormone misuse.

The growth hormone-2000 biomarker method, based on the measurements of insulin-like growth factor-I and the amino-terminal pro-peptide of type III collagen, has been developed as a powerful technique for the detection of growth hormone misuse by athletes. Insulin-like growth factor-I and amino-terminal pro-peptide of type III collagen are combined in gender-specific formulas to create the growth hormone-2000 score, which is used to determine whether growth hormone has been administered. To comply with World Anti-Doping Agency regulations, each analyte must be measured by two methods. Insulin-like growth factor-I and amino-terminal pro-peptide of type III collagen can be measured by a number of approved methods, each leading to its own growth hormone-2000 score. Single decision limits for each growth hormone-2000 score have been introduced and developed by Bassett, Erotokritou-Mulligan, Holt, Böhning and their co-authors in a series of papers. These have been incorporated into the guidelines of the World Anti-Doping Agency. A joint decision limit was constructed based on the sample correlation between the two growth hormone-2000 scores generated from an available sample to increase the sensitivity of the biomarker method. This paper takes this idea further into a fully developed statistical approach. It constructs combined decision limits when two growth hormone-2000 scores from different assay combinations are used to decide whether an athlete has been misusing growth hormone. The combined decision limits are directly related to tolerance regions and constructed using a Bayesian approach. It is also shown to have highly satisfactory frequentist properties. The new approach meets the required false-positive rate with a pre-specified level of certainty.

Pathogenic SLC25A26 variants impair SAH transport activity causing mitochondrial disease.

The SLC25A26 gene encodes a mitochondrial inner membrane carrier that transports S-adenosylmethionine (SAM) into the mitochondrial matrix in exchange for S-adenosylhomocysteine (SAH). SAM is the predominant methyl-group donor for most cellular methylation processes, of which SAH is produced as a by-product. Pathogenic, biallelic SLC25A26 variants are a recognized cause of mitochondrial disease in children, with a severe neonatal onset caused by decreased SAM transport activity. Here, we describe two, unrelated adult cases, one of whom presented with recurrent episodes of severe abdominal pain and metabolic decompensation with lactic acidosis. Both patients had exercise intolerance and mitochondrial myopathy associated with biallelic variants in SLC25A26, which led to marked respiratory chain deficiencies and mitochondrial histopathological abnormalities in skeletal muscle that are comparable to those previously described in early-onset cases. We demonstrate using both mouse and fruit fly models that impairment of SAH, rather than SAM, transport across the mitochondrial membrane is likely the cause of this milder, late-onset phenotype. Our findings associate a novel pathomechanism with a known disease-causing protein and highlight the quests of precision medicine in optimizing diagnosis, therapeutic intervention and prognosis.

Anabolic steroid use and ischaemic stroke in a young fitness enthusiast.

We report a case of ischaemic stroke in a 34-year-old male recreational bodybuilder following a 3-month period of anabolic androgenic steroid (AAS) use and 1-month period of 'post-cycle therapy' (tamoxifen and clomiphene citrate), the latter treatments aimed at restoring normal endogenous testosterone production after initial AAS use. We hypothesise a transient drug-related prothrombotic state with paradoxical embolisation via an atrial septal defect which was later found on bubble echocardiogram. We highlight a rare but important cause of stroke in younger patients which is relevant given the increasing use of AAS misuse among casual fitness enthusiasts. We explore the various possible mechanisms by which AAS use can increase ischaemic stroke risk in such patients.

The effects of recombinant human insulin-like growth factor-1/insulin-like growth factor binding protein-3 administration on lipid and carbohydrate metabolism in recreational athletes.

OBJECTIVE: Previous studies suggested that recombinant human IGF-1 (rhIGF-1) administration affects carbohydrate and lipid metabolism in healthy people and in people with diabetes. This study aimed to determine the effects of rhIGF-1/rhIGF binding protein-3 (rhIGFBP-3) administration on glucose homeostasis and lipid metabolism in healthy recreational athletes. DESIGN AND SETTING: Randomized, double-blind, placebo-controlled rhIGF-1/rhIGFBP-3 administration study at Southampton General Hospital, UK. PARTICIPANTS: 56 recreational athletes (30 men, 26 women). METHODS: Participants were randomly assigned to receive placebo, low-dose rhIGF-1/rhIGFBP-3 (30 mg/day) or high-dose rhIGF-1/rhIGFBP-3 (60 mg/day) for 28 days. The following variables were measured before and immediately after the treatment period: fasting lipids, glucose, insulin, C-peptide and glycated haemoglobin. The homeostatic model assessment (HOMA-IR) was used to estimate insulin sensitivity and indirect calorimetry to assess substrate oxidation rates. The general linear model approach was used to compare treatment group changes with the placebo group. RESULTS: Compared with the placebo group, there was a significant reduction in fasting triglycerides in participants treated with high-dose rhIGF-1/rhIGFBP-3 (p = .030), but not in the low-dose group (p = .390). In women, but not in men, there were significant increases in total cholesterol (p = .003), HDL cholesterol (p = .001) and LDL cholesterol (p = .008). These lipid changes were associated with reduced fasting insulin (p = .010), C-peptide (p = .001) and HOMA-IR (p = .018) in women and reduced C-peptide (p = .046) in men. CONCLUSIONS: rhIGF-1/rhIGFBP-3 administration for 28 days reduced insulin concentration, improved insulin sensitivity and had significant effects on lipid profile including decreased fasting triglycerides.

Comparison of normal distribution-based and nonparametric decision limits on the GH-2000 score for detecting growth hormone misuse (doping) in sport.

This paper is motivated by the GH-2000 biomarker test, though the discussion is applicable to other diagnostic tests. The GH-2000 biomarker test has been developed as a powerful technique to detect growth hormone misuse by athletes, based on the GH-2000 score. Decision limits on the GH-2000 score have been developed and incorporated into the guidelines of the World Anti-Doping Agency (WADA). These decision limits are constructed, however, under the assumption that the GH-2000 score follows a normal distribution. As it is difficult to affirm the normality of a distribution based on a finite sample, nonparametric decision limits, readily available in the statistical literature, are viable alternatives. In this paper, we compare the normal distribution-based and nonparametric decision limits. We show that the decision limit based on the normal distribution may deviate significantly from the nominal confidence level 1-α or nominal FPR γ when the distribution of the GH-2000 score departs only slightly from the normal distribution. While a nonparametric decision limit does not assume any specific distribution of the GH-2000 score and always guarantees the nominal confidence level and FPR, it requires a much larger sample size than the normal distribution-based decision limit. Due to the stringent FPR of the GH-2000 biomarker test used by WADA, the sample sizes currently available are much too small, and it will take many years of testing to have the minimum sample size required, in order to use the nonparametric decision limits. Large sample theory about the normal distribution-based and nonparametric decision limits is also developed in this paper to help understanding their behaviours when the sample size is large.

Exact statistical calculation of the uncertainty term in the decision limits of the GH-2000 score for growth hormone misuse (doping) detection.

The GH-2000 score has been developed as a powerful and unique technique for the detection of growth hormone misuse by sportsmen and women. The score depends upon the measurement of two growth hormone sensitive markers, insulin-like growth factor-I and the amino-terminal pro-peptide of type III collagen. It also includes a term to adjust for the age of the athlete. Decision limits for the GH-2000 score have been developed and are incorporated into the guidelines of the World Anti-Doping Agency. These decision limits are derived by setting a 1 in 10,000 false-positive rate rule. As these decision limits are estimated from samples of GH-2000 scores, they carry uncertainty. In previous work, this uncertainty has been addressed by establishing an upper 95% confidence interval for the true decision limits based on a normal approximation which has been shown to be appropriate if sample sizes are large (such as 1000 and above). Here, we show that these approximations, whether reasonable or not, can be entirely avoided by developing an upper 95% confidence interval for the true decision limits using an approach based upon the t-distribution. While there are considerable differences for smaller sample sizes, these become negligible when the sample size is large such as 1000 and above.

A correction to the age-adjustment of the GH-2000 score used in the detection of growth hormone misuse.

OBJECTIVE: The GH-2000 biomarker test has been introduced by the World Anti-Doping Agency as a method of detecting growth hormone misuse in professional sport. The test involves the measurement insulin-like growth factor-I and the amino-terminal pro-peptide of type III collagen (P-III-NP) which increase in a dose-dependent manner in response to GH. These measurements are combined in sex specific formulae that include an age adjustment. The original age adjustment overcorrects the effect of age in male athletes and could potentially place older men at a disadvantage. The purpose of this note is to investigate the performance of a previously suggested correction term in two new and larger data sets. RESULTS: The GH-2000 score was calculated for 7307 samples obtained from 15 accredited WADA laboratories in 2017 and 3916 samples measured at Drug Control Centre, King's College London, UK between 2013 and 2017. The GH-2000 scores were investigated for positive age effects using standard regression modelling. As previously, all analyses confirmed a positive age effect. Applying the earlier suggested correction term of 0.032 × age showed a significant over-correction leading to a negative association of the GH-2000 score with age. We now suggest a smaller age correction of 0.020 × age, which corresponds to the smallest effect found in the earlier studies.

Why do endocrine profiles in elite athletes differ between sports?

BACKGROUND: Endocrine profiles have been measured on blood samples obtained immediately post-competition from 693 elite athletes from 15 Olympic Sports competing at National or International level; four were subsequently excluded leaving 689 for the current analysis. METHODS: Body composition was measured by bioimpedance in a sub-set of 234 (146 men and 88 women) and from these data a regression model was constructed that enabled 'estimated' lean body mass and fat mass to be calculated on all athletes. One way ANOVA was used to assess the differences in body composition and endocrine profiles between the sports and binary logistical regression to ascertain the characteristic of a given sport compared to the others. RESULTS: The results confirmed many suppositions such as basketball players being tall, weightlifters short and cross-country skiers light. The hormone profiles were more surprising with remarkably low testosterone and free T3 (tri-iodothyronine) in male powerlifters and high oestradiol, SHBG (sex hormone binding globulin) and prolactin in male track and field athletes. Low testosterone concentrations were seen 25.4% of male elite competitors in 12 of the 15 sports and high testosterone concentrations in 4.8% of female elite athletes in 3 of the 8 sports tested. Interpretation of the results is more difficult; some of the differences between sports are at least partially due to differences in age of the athletes but the apparent differences between sports remain significant after adjusting for age. The prevalence of 'hyperandrogenism' (as defined by the IAAF (International Association of Athletics Federations) and IOC (International Olympic Committee)) amongst this cohort of 231 elite female athletes was the highest so far recorded and the very high prevalence of 'hypoandrogenism' in elite male athletes a new finding. CONCLUSIONS: It is unclear whether the differences in hormone profiles between sports is a reason why they become elite athletes in that sport or is a consequence of the arduous processes involved. For components of body composition we know that most have a major genetic component and this may well be true for endocrine profiles.

Isolated aortic root dilation in homocystinuria.

BACKGROUND: Vascular complications in homocystinuria have been known for many years, but there have been no reports to date on involvement of the ascending aorta. METHODS: We conducted a cross-sectional study of patients with homocystinuria, known to a single metabolic centre, and evaluated in 2016 with a transthoracic echocardiogram. Aortic root dilation was defined as Z-score ≥ 2.0 SD, and graded mild (Z-score 2.0-3.0), moderate (Z-score 3.01-4.0) and severe (Z-score > 4.0). RESULTS: The study population included 34 patients, median age of 44.3 years (IQR 33.3-52.2), 50% males, 69% diagnosed aged <18 years and 29% pyridoxine-responsive. Eight (24%) had a history of hypertension. Seven patients (21%) were found to have a dilation of the aortic root, mild in two cases (6%), moderate in four (12%) and severe in one (3%). None had dilation of the ascending aorta. Significant aortic regurgitation, secondary to moderate aortic root dilation, was documented in two patients. A single patient had significant mitral regurgitation due to prolapse of both valve leaflets, as well as mild aortic root dilation. Comparing patients with a dilation of the aortic root to those without, there were no significant clinical, laboratory or echocardiographic differences, with the only exception being that the diameter of the ascending aorta was larger in the group with a dilated aortic root, albeit within normal limits. CONCLUSIONS: A subset of patients with homocystinuria have isolated dilation of the aortic root similar to that observed in Marfan syndrome.

Use of FGF-21 as a Biomarker of Mitochondrial Disease in Clinical Practice.

Recent work has suggested that fibroblast growth factor-21 (FGF-21) is a useful biomarker of mitochondrial disease (MD). We routinely measured FGF-21 levels on patients who were investigated at our centre for MD and evaluated its diagnostic performance based on detailed genetic and other laboratory findings. Patients' FGF-21 results were assessed by the use of age-adjusted z-scores based on normalised FGF-21 values from a healthy population. One hundred and fifty five patients were investigated. One hundred and four of these patients had molecular evidence for MD, 27 were deemed to have disorders other than MD (non-MD), and 24 had possible MD. Patients with defects in mitochondrial DNA (mtDNA) maintenance (n = 32) and mtDNA rearrangements (n = 17) had the highest median FGF-21 among the MD group. Other MD patients harbouring mtDNA point mutations (n = 40) or mutations in other autosomal genes (n = 7) and those with partially characterised MD had lower FGF-21 levels. The area under the receiver operating characteristic curve for distinguishing MD from non-MD patients was 0.69. No correlation between FGF-21 and creatinine, creatine kinase, or cardio-skeletal myopathy score was found. FGF-21 was significantly associated with plasma lactate and ocular myopathy. Although FGF-21 was found to have a low sensitivity for detecting MD, at a z-score of 2.8, its specificity was above 90%. We suggest that a high serum concentration of FGF-21 would be clinically useful in MD, especially in adult patients with chronic progressive external ophthalmoplegia, and may enable bypassing muscle biopsy and directly opting for genetic analysis. Availability of its assay has thus modified our diagnostic pathway.

Novel markers to detect recombinant human insulin-like growth factor-I (rhIGF-I)/rhIGF binding protein-3 (rhIGFBP-3) misuse in athletes.

Insulin-like growth factor-I (IGF-I) is abused by elite athletes for its metabolic and anabolic effects. We have previously shown that it is possible to detect IGF-I misuse by measuring serum IGF-I and procollagen type III amino-terminal propeptide (P-III-NP) but a pilot study suggested measuring IGF-II, IGF binding protein-2 (IGFBP-2) and acid-labile subunit (ALS) may improve the detection of IGF-I administration. The aim of the study was to assess this in a randomized controlled trial. Twenty-six female and 30 male recreational athletes were randomized to 28 days' treatment with placebo or recombinant human (rh)IGF-I/rhIGF binding protein-3 (IGFBP-3) complex (30 mg/day or 60 mg/day), followed by 56 days' washout. IGF-II, IGFBP-2 and ALS (women only) were measured using commercial immunoassays. IGFBP-2 increased and IGF-II decreased in response to both low and high dose rhIGF-I/rhIGFBP-3 in both women and men while ALS decreased in women in response to high dose rhIGF-I/rhIGFBP-3. Two days after discontinuing treatment, significant differences remained between the three treatment groups in IGFBP-2 and IGF-II, but not ALS. Thereafter there were no significant differences between the three treatment groups in any of the markers. Combining IGF-I with IGF-II and/or IGFBP-2 improved the performance of the test to detect rhIGF-I/rhIGFBP-3 administration in both women and men. Copyright © 2016 John Wiley & Sons, Ltd.

Statistical methodology for age-adjustment of the GH-2000 score detecting growth hormone misuse.

BACKGROUND: The GH-2000 score has been developed as a powerful and unique technique for the detection of growth hormone misuse by sportsmen and women. The score depends upon the measurement of two growth hormone (GH) sensitive markers, insulin-like growth factor-I (IGF-I) and the amino-terminal pro-peptide of type III collagen (P-III-NP). With the collection and establishment of an increasingly large database it has become apparent that the score shows a positive age effect in the male athlete population, which could potentially place older male athletes at a disadvantage. METHODS: We have used results from residual analysis of the general linear model to show that the residual of the GH-2000 score when regressed on the mean-age centred age is an appropriate way to proceed to correct this bias. As six GH-2000 scores are possible depending on the assays used for determining IGF-I and P-III-NP, methodology had to be explored for including six different age effects into a unique residual. Meta-analytic techniques have been utilized to find a summary age effect. RESULTS: The age-adjusted GH-2000 score, a form of residual, has similar mean and variance as the original GH-2000 score and, hence, the developed decision limits show negligible change when compared to the decision limits based on the original score. We also show that any further scale-transformation will not change the adjusted score. Hence the suggested adjustment is optimal for the given data. The summary age effect is homogeneous across the six scores, and so the generic adjustment of the GH-2000 score formula is justified. CONCLUSIONS: A final revised GH-2000 score formula is provided which is independent of the age of the athlete under consideration.

The Effects of Recombinant Human Insulin-Like Growth Factor-I/Insulin-Like Growth Factor Binding Protein-3 Administration on Body Composition and Physical Fitness in Recreational Athletes.

CONTEXT: IGF-I is thought to mediate many of the anabolic actions of GH, and there are anecdotal reports that IGF-I is misused by elite athletes. There is no published evidence regarding the effects of IGF-I administration on athletic performance. OBJECTIVE: The objective of the study was to investigate the effects of IGF-I administration on body composition and physical fitness in recreational athletes. DESIGN AND SETTING: This was a randomized, double-blind, placebo-controlled recombinant human (rh) IGF-I/rhIGF binding protein (IGFBP)-3 administration study at Southampton General Hospital (Southampton, United Kingdom). PARTICIPANTS: Fifty-six recreational athletes (30 men, 26 women) participated in the study. INTERVENTION: Participants were randomly assigned to receive placebo, low-dose rhIGF-I/rhIGFBP-3 (30 mg/d), or high dose rhIGF-I/rhIGFBP-3 (60 mg/d) for 28 days. Body composition (assessed by dual energy x-ray absorptiometry) and cardiorespiratory fitness (assessed by incremental treadmill test) were measured before and immediately after treatment. Within-individual changes after treatment were analyzed using paired t tests. RESULTS: There were no significant changes in body fat mass or lean body mass in women or men after the administration of the rhIGF-I/rhIGFBP-3 complex. There was a significant increase in maximal oxygen consumption (VO2 max) after treatment. When women and men and low- and high-dose treatment groups were combined, mean VO2 max increased by approximately 7% (P = .001). No significant change in VO2 max was observed in the placebo group. CONCLUSIONS: rhIGF-I/rhIGFBP-3 administration for 28 days improves aerobic performance in recreational athletes, but there are no effects on body composition.