Resumption of ovulation in anovulatory women with PCOS and obesity is associated with reduction of 11ß-hydroxyandrostenedione concentrations.

STUDY QUESTION: Is resumption of ovulation after a 6-month lifestyle intervention in women with PCOS and obesity associated with differential changes in endocrine and metabolic parameters (weight, insulin resistance, anti-Müllerian hormone (AMH), and androgens) compared to women with PCOS who remained anovulatory? SUMMARY ANSWER: Resumption of ovulation after a 6-month lifestyle intervention in women with PCOS and obesity is associated with changes in serum 11ß-hydroxyandrostenedione (11OHA4) concentrations. WHAT IS KNOWN ALREADY: Lifestyle interventions have been shown to reduce clinical and biochemical hyperandrogenism in women with PCOS. Weight loss of 5-10% may reverse anovulatory status, thereby increasing natural conception rates. However, the mechanisms underlying why some women with PCOS remain anovulatory and others resume ovulation after weight loss are unclear. Reproductive characteristics at baseline and a greater degree of change in endocrine and metabolic features with lifestyle intervention may be crucial for ovulatory response. STUDY DESIGN, SIZE, DURATION: We used data and samples originating from an earlier randomized controlled trial (RCT), which examined the efficacy of a 6-month lifestyle intervention prior to infertility treatment compared to prompt infertility treatment on live birth rate in women with obesity. A total of 577 women with obesity (BMI > 29 kg/m2) were randomized between 2009 and 2012. Anovulatory women with PCOS who were allocated to the intervention arm of the original RCT (n = 95) were included in the current analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS: We defined women as having resumed ovulation (RO+) based on the following criteria: spontaneous pregnancy; or assignment to expectant management; or IUI in natural cycles as the treatment strategy after lifestyle intervention. Steroid hormones were measured using liquid chromatography tandem mass spectrometry. Generalized estimating equations with adjustment for baseline measures and interaction between group and time was used to examine differences in changes of endocrine and metabolic parameters between RO+ (n = 34) and persistently anovulatory women (RO-, n = 61) at 3 and 6 months after intervention. MAIN RESULTS AND THE ROLE OF CHANCE: At baseline, the mean ± SD age was 27.5 ± 3.6 years in the RO+ group and 27.9 ± 4.1 years in the RO- group (P = 0.65), and the mean ± SD weights were 101.2 ± 9.5 kg and 105.0 ± 14.6 kg, respectively (P = 0.13). Baseline AMH concentrations showed significant differences between RO+ and RO- women (median and interquartile range [IQR] 4.7 [3.2; 8.3] versus 7.2 [5.3; 10.8] ng/ml, respectively). Baseline androgen concentrations did not differ between the two groups. During and after lifestyle intervention, both groups showed weight loss; changes in 11OHA4 were significantly different between the RO+ and RO groups (P-value for interaction = 0.03). There was a similar trend for SHBG (interaction P-value = 0.07), and DHEA-S (interaction P-value = 0.06), with the most pronounced differences observed in the first 3 months. Other parameters, such as AMH and FAI, decreased over time but with no difference between the groups. LIMITATIONS, REASONS FOR CAUTION: No high-resolution transvaginal ultrasonography was used to confirm ovulatory status at the end of the lifestyle program. The small sample size may limit the robustness of the results. WIDER IMPLICATIONS OF THE FINDINGS: Reduction of androgen concentrations during and after lifestyle intervention is associated with recovery of ovulatory cycles. If our results are confirmed in other studies, androgen concentrations could be monitored during lifestyle intervention to provide individualized recommendations on the timing of resumption of ovulation in anovulatory women with PCOS and obesity. STUDY FUNDING/COMPETING INTEREST(S): The study was supported by a grant from ZonMw, the Dutch Organization for Health Research and Development (50-50110-96-518). The Department of Obstetrics and Gynecology of the UMCG received an unrestricted educational grant from Ferring Pharmaceuticals BV, The Netherlands. A.H. reports consultancy for the development and implementation of a lifestyle App MyFertiCoach developed by Ferring Pharmaceutical Company. All other authors have no conflicts to declare. TRIAL REGISTRATION NUMBER: The LIFEstyle RCT was registered at the Dutch trial registry (NTR 1530).

LC-MS/MS in clinical chemistry: Did it live up to its promise?: Consideration from the Dutch EQAS organisation.

BACKGROUND: Over the past decade the use of LC-MS/MS has increased significantly in the hospital laboratories. Clinical laboratories have switched from immunoassays to LC-MS/MS methods due to the promise of improvements in sensitivity and specificity, better standardization with often non-commutable international standards, and better between-laboratory comparison. However, it remains unclear whether routine performance of the LC-MS/MS methods have met these expectations. METHOD: This study examined the EQAS results, from the Dutch SKML, of serum cortisol, testosterone, 25OH-vitaminD and cortisol in urine and saliva over 9 surveys (2020 to first half of 2021). RESULTS: The study found a significant increase in the number of compounds and in the number of results measured in the different matrices, with LC-MS/MS over a period of eleven years. In 2021, approximately 4000 LC-MS/MS results were submitted (serum: urine: saliva = 58:31:11%) compared to only 34 in 2010. When compared to the individual immunoassays, the LC-MS/MS based methods for serum cortisol, testosterone and 25OH-vitaminD showed comparable but also higher between-laboratory CVs in different samples of the surveys. For cortisol, testosterone and 25OH-vitaminD the median CV was 6.8%, 6.1% and 4.7% respectively for the LC-MS/MS compared to 3.9-8.0%,4.5-6.7%, and 7.5-18.3% for immunoassays. However, the bias and imprecision of the LC-MS/MS was better than that of the immunoassays. CONCLUSION: Despite the expectation that LC-MS/MS methods would result in smaller between-laboratory differences, as they are relatively matrix independent and better to standardize, the results of the SKML round robins do not reflect this for some analytes and may be in part explained by the fact that in most cases laboratory developed tests were used.

The increasing importance of LNAA supplementation in phenylketonuria at higher plasma phenylalanine concentrations.

BACKGROUND: Large neutral amino acid (LNAA) treatment has been suggested as alternative to the burdensome severe phenylalanine-restricted diet. While its working mechanisms and optimal composition have recently been further elucidated, the question whether LNAA treatment requires the natural protein-restricted diet, has still remained. OBJECTIVE: Firstly, to determine whether an additional liberalized natural protein-restricted diet could further improve brain amino acid and monoamine concentrations in phenylketonuria mice on LNAA treatment. Secondly, to compare the effect between LNAA treatment (without natural protein) restriction and different levels of a phenylalanine-restricted diet (without LNAA treatment) on brain amino acid and monoamine concentrations in phenylketonuria mice. DESIGN: BTBR Pah-enu2 mice were divided into two experimental groups that received LNAA treatment with either an unrestricted or semi phenylalanine-restricted diet. Control groups included Pah-enu2 mice on the AIN-93 M diet, a severe or semi phenylalanine-restricted diet without LNAA treatment, and wild-type mice receiving the AIN-93 M diet. After ten weeks, brain and plasma samples were collected to measure amino acid profiles and brain monoaminergic neurotransmitter concentrations. RESULTS: Adding a semi phenylalanine-restricted diet to LNAA treatment resulted in lower plasma phenylalanine but comparable brain amino acid and monoamine concentrations as compared to LNAA treatment (without phenylalanine restriction). LNAA treatment (without phenylalanine restriction) resulted in comparable brain monoamine but higher brain phenylalanine concentrations compared to the severe phenylalanine-restricted diet, and significantly higher brain monoamine but comparable phenylalanine concentrations as compared to the semi phenylalanine-restricted diet. CONCLUSIONS: Present results in PKU mice suggest that LNAA treatment in PKU patients does not need the phenylalanine-restricted diet. In PKU mice, LNAA treatment (without phenylalanine restriction) was comparable to a severe phenylalanine-restricted diet with respect to brain monoamine concentrations, notwithstanding the higher plasma and brain phenylalanine concentrations, and resulted in comparable brain phenylalanine concentrations as on a semi phenylalanine-restricted diet.

Pharmacological Screening Identifies SHK242 and SHK277 as Novel Arginase Inhibitors with Efficacy against Allergen-Induced Airway Narrowing In Vitro and In Vivo.

Arginase is a potential target for asthma treatment. However, there are currently no arginase inhibitors available for clinical use. Here, a novel class of arginase inhibitors was synthesized, and their efficacy was pharmacologically evaluated. The reference compound 2(S)-amino-6-boronohexanoic acid (ABH) and >200 novel arginase inhibitors were tested for their ability to inhibit recombinant human arginase 1 and 2 in vitro. The most promising compounds were separated as enantiomers. Enantiomer pairs SHK242 and SHK243, and SHK277 and SHK278 were tested for functional efficacy by measuring their effect on allergen-induced airway narrowing in lung slices of ovalbumin-sensitized guinea pigs ex vivo. A guinea pig model of acute allergic asthma was used to examine the effect of the most efficacious enantiopure arginase inhibitors on allergen-induced airway hyper-responsiveness (AHR), early and late asthmatic reactions (EAR and LAR), and airway inflammation in vivo. The novel compounds were efficacious in inhibiting arginase 1 and 2 in vitro. The enantiopure SHK242 and SHK277 fully inhibited arginase activity, with IC50 values of 3.4 and 10.5 µM for arginase 1 and 2.9 and 4.0 µM for arginase 2, respectively. Treatment of slices with ABH or novel compounds resulted in decreased ovalbumin-induced airway narrowing compared with control, explained by increased local nitric oxide production in the airway. In vivo, ABH, SHK242, and SHK277 protected against allergen-induced EAR and LAR but not against AHR or lung inflammation. We have identified promising novel arginase inhibitors for the potential treatment of allergic asthma that were able to protect against allergen-induced early and late asthmatic reactions. SIGNIFICANCE STATEMENT: Arginase is a potential drug target for asthma treatment, but currently there are no arginase inhibitors available for clinical use. We have identified promising novel arginase inhibitors for the potential treatment of allergic asthma that were able to protect against allergen-induced early and late asthmatic reactions. Our new inhibitors show protective effects in reducing airway narrowing in response to allergens and reductions in the early and late asthmatic response.

The Effect of Tryptophan 2,3-Dioxygenase Inhibition on Kynurenine Metabolism and Cognitive Function in the APP23 Mouse Model of Alzheimer's Disease.

Alzheimer's disease (AD) is associated with progressive endogenous neurotoxicity and hampered inflammatory regulation. The kynurenine (Kyn) pathway, which is controlled by tryptophan 2,3-dioxygenase (TDO), produces neuroactive and anti-inflammatory metabolites. Age-related Kyn pathway activation might contribute to AD pathology in humans, and inhibition of TDO was found to reduce AD-related cellular toxicity and behavioral deficits in animal models. To further explore the effect of aging on the Kyn pathway in the context of AD, we analyzed Kyn metabolite profiles in serum and brain tissue of the APP23 amyloidosis mouse model. We found that aging had genotype-independent effects on Kyn metabolite profiles in serum, cortex, hippocampus and cerebellum, whereas serum concentrations of many Kyn metabolites were reduced in APP23 mice. Next, to further establish the role of TDO in AD-related behavioral deficits, we investigated the effect of long-term pharmacological TDO inhibition on cognitive performance in APP23 mice. Our results indicated that TDO inhibition reversed recognition memory deficits without producing measurable changes in cerebral Kyn metabolites. TDO inhibition did not affect spatial learning and memory or anxiety-related behavior. These data indicate that age-related Kyn pathway activation is not specific for humans and could represent a cross-species phenotype of aging. These data warrant further investigation on the role of peripheral Kyn pathway disturbances and cerebral TDO activity in AD pathophysiology.

Influence of prednisolone on parameters of de novo lipogenesis and indices for stearoyl-CoA- and Δ6- desaturase activity in healthy males: A Post-hoc analysis of a randomized, placebo-controlled, double-blind trial.

Glucocorticoid treatment decreases liver insulin sensitivity and may modify fatty acid metabolism. We investigated the influence of oral prednisolone on indices for de novo lipogenesis (DNLi), stearoyl-CoA desaturase (SCDi) and Δ6-desaturase (D6Di) activity in healthy males. In addition, we explored whether the changes may be associated with prednisolone-induced changes in glucose and lipid metabolism and insulin sensitivity. Thirty-two healthy young males (mean ±â€¯SD age 22 ±â€¯3 years, BMI 22.4 ±â€¯1.7 kg/m2) were allocated to receive prednisolone 7.5 mg/day (PRED7.5; n = 12), prednisolone 30 mg/day (PRED30; n = 12), or placebo (n = 8) in a randomized double-blind fashion for 2 weeks. Fatty acid compositions of plasma cholesteryl esters (CE), phospholipids (PL) and triglycerides (TG) were measured at baseline and on day 14. DNLi, SCDi and D6Di were estimated from product/precursor ratios in CE, with DNLi primary deriving from 16:1ω7/18:2ω6, SCDi from 16:1ω7/16:0 and D6Di from 22:6ω3/20:5ω3. Ratios were also assessed in PL and TG. In CE, PRED30 increased DNLi by 51.2 [95%CI 14.8; 87.6]%, increased SCDi by 48.6 [18.7; 78.5]%, and decreased D6Di by 57.7 [-91.8; -23.5]% (p ≤ 0.01 for all, compared to placebo). The prednisolone-induced increases in DNLi and SCDi were positively correlated with insulin sensitivity (r = 0.35 and 0.50, respectively). Similar results were found in PL and TG. Prednisolone dose-dependently increases DNLi and SCDi and decreases D6Di in plasma CE, PL and TG in healthy males after 2 weeks. The observed unfavorable effects on fatty acid metabolism were related to the induction of glucocorticoid-induced insulin resistance.

Prenatal and pubertal testosterone affect brain lateralization.

After decades of research, the influence of prenatal testosterone on brain lateralization is still elusive, whereas the influence of pubertal testosterone on functional brain lateralization has not been investigated, although there is increasing evidence that testosterone affects the brain in puberty. We performed a longitudinal study, investigating the relationship between prenatal testosterone concentrations in amniotic fluid, pubertal testosterone concentrations in saliva, and brain lateralization (measured with functional Transcranial Doppler ultrasonography (fTCD)) of the Mental Rotation, Chimeric Faces and Word Generation tasks. Thirty boys and 30 girls participated in this study at the age of 15 years. For boys, we found a significant interaction effect between prenatal and pubertal testosterone on lateralization of Mental Rotation and Chimeric Faces. In the boys with low prenatal testosterone levels, pubertal testosterone was positively related to the strength of lateralization in the right hemisphere, while in the boys with high prenatal testosterone levels, pubertal testosterone was negatively related to the strength of lateralization. For Word Generation, pubertal testosterone was negatively related to the strength of lateralization in the left hemisphere in boys. For girls, we did not find any significant effects, possibly because their pubertal testosterone levels were in many cases below quantification limit. To conclude, prenatal and pubertal testosterone affect lateralization in a task-specific way. Our findings cannot be explained by simple models of prenatal testosterone affecting brain lateralization in a similar way for all tasks. We discuss alternative models involving age dependent effects of testosterone, with a role for androgen receptor distribution and efficiency.

Congenital adrenal hyperplasia as a cause of adrenal incidentaloma.

Congenital adrenal hyperplasia (CAH) can present as a benign adrenal tumour, which should be treated medically. The diagnosis of CAH must be considered in a patient presenting with adrenal incidentaloma in order to avoid unnecessary adrenalectomy. Urinary steroid profiling is a useful diagnostic tool to identify the presence of CAH.

The association between the hypothalamic pituitary adrenal axis and tryptophan metabolism in persons with recurrent major depressive disorder and healthy controls.

OBJECTIVES: Persistent changes in serotonergic and hypothalamic pituitary adrenal (HPA) axis functioning are implicated in recurrent types of major depressive disorder (MDD). Systemic tryptophan levels, which influence the rate of serotonin synthesis, are regulated by glucocorticoids produced along the HPA axis. We investigated tryptophan metabolism and its association with HPA axis functioning in single episode MDD, recurrent MDD and non-depressed individuals. METHODS: We included depressed individuals (n = 1320) and controls (n = 406) from the Netherlands Study of Depression and Anxiety (NESDA). The kynurenine to tryptophan ratio (kyn/trp ratio) was established using serum kynurenine and tryptophan levels. Several HPA axis parameters were calculated using salivary cortisol samples. We adjusted the regression analyses for a wide range of potential confounders and differentiated between single episode MDD, recurrent MDD and control. RESULTS: Tryptophan, kynurenine and the kyn/trp ratio did not differ between controls and depressed individuals. Increased evening cortisol levels were associated with a decreased kyn/trp ratio in the total sample (Crude: ß = -.102, p < .001; Adjusted: ß = -.083, p < .001). This association was found to be restricted to recurrently depressed individuals (Crude: ß = -.196, p < .001; Adjusted: ß = -.145, p = .001). Antidepressant treatment did not affect this association. CONCLUSIONS: Our results suggest that an imbalance between HPA axis function and tryptophan metabolism could be involved in recurrent depression.

[Hypocortisolism associated with nephrotic syndrome]. / Hypocortisolisme bij het nefrotisch syndroom.

BACKGROUND: With nephrotic syndrome, cortisol levels may be falsely lowered by loss of cortisol-binding globulin (CBG) in the urine. An incorrect diagnosis of adrenal insufficiency could therefore be made. CASE DESCRIPTION: We describe the case of a 52-year-old female with nephrotic syndrome that did not sufficiently respond to medication. Treatment management was complicated by symptomatic hypotension, which was thought to be caused by adrenal insufficiency. The cortisol levels in the blood were low and a clinical cause could not be identified. However, free cortisol in the saliva appeared normal and serum CBG levels were low; this therefore precluded adrenal insufficiency. After complete remission of the nephrotic syndrome, cortisol levels normalised. CONCLUSION: The reduced cortisol level in this patient was caused by the reduced CBG level due to loss associated with nephrotic syndrome. First and foremost it is important to indicate an abnormal laboratory result within an existing disease, before making a new diagnosis of concomitant disease.

The relationship between 63days of 24-h urinary free cortisol and hair cortisol levels in 10 healthy individuals.

BACKGROUND: Interest in measuring cortisol in scalp hair is increasing because of its assumed ability to provide a historical timeline of previous systemic levels of cortisol. Yet, it remains uncertain how well hair cortisol represents the total systemic secretion of cortisol over time. METHODS: Ten healthy individuals collected 24-h urine samples for 63 consecutive days and provided a hair sample at the end of the study period. 24-h urinary creatinine levels in every urine sample were determined to assess completeness of the samples. Cortisol levels in 24-h urine samples and in hair were measured with liquid chromatography tandem mass spectrometry. The correlations between urinary cortisol and hair cortisol were calculated using Kendall's tau. RESULTS: We found a nonsignificant moderate correlation between average urinary cortisol secretion and average hair cortisol concentration rт=0.422, p=0.089. CONCLUSIONS: Hair cortisol concentration correlates low to moderately with 24-h urinary cortisol concentration over a period of 63days.

Local gene therapy with indoleamine 2,3-dioxygenase protects against development of transplant vasculopathy in chronic kidney transplant dysfunction.

Chronic transplant dysfunction (CTD) is the primary cause of late allograft loss in kidney transplantation. Indoleamine 2,3-dioxygenase (IDO) is involved in fetomaternal tolerance and IDO gene therapy inhibits acute rejection following kidney transplantation. The aim of this study is to investigate whether gene therapy with IDO is able to attenuate CTD. Transplantation was performed in a rat Dark-Agouti to Wistar-Furth CTD model. Donor kidneys were incubated either with an adenovirus carrying IDO gene, a control adenovirus or saline. During the first 10 days recipients received low-dose cyclosporine. Body weight, blood pressure, serum creatinine and proteinuria were measured every 2 weeks. Rats were killed after 12 weeks. IDO had a striking beneficial effect on transplant vasculopathy at week 12. It also significantly improved body weight gain; it reduced blood pressure and decreased proteinuria during the follow-up. However, it did not affect the kidney function. In addition, IDO therapy significantly decreased the number of graft-infiltrating macrophages at week 12. The messenger RNA levels of forkhead box p3 and transforming grow factor-ß were elevated in the IDO treated group at week 12. Here we show for first time a clear beneficial effect of local IDO gene therapy especially on transplant vasculopathy in a rat model of renal CTD.

Serotonergic perturbations in dystonia disorders-a systematic review.

Dystonia is a hyperkinetic movement disorder characterized by sustained or intermittent muscle contractions. Emerging data describe high prevalences of non-motor symptoms, including psychiatric co-morbidity, as part of the phenotype of dystonia. Basal ganglia serotonin and serotonin-dopamine interactions gain attention, as imbalances are known to be involved in extrapyramidal movement and psychiatric disorders. We systematically reviewed the literature for human and animal studies relating to serotonin and its role in dystonia. An association between dystonia and the serotonergic system was reported with decreased levels of 5-hydroxyindolacetic acid, the main metabolite of serotonin. A relation between dystonia and drugs affecting the serotonergic system was described in 89 cases in 49 papers. Psychiatric co-morbidity was frequently described, but likely underestimated as it was not systematically examined. Currently, there are no good (pharmaco)therapeutic options for most forms of dystonia or associated non-motor symptoms. Further research using selective serotonergic drugs in appropriate models of dystonia is required to establish the role of the serotonergic system in dystonia and to guide us to new therapeutic strategies.

SDH Subunit Mutation Status in Saliva: Genetic Testing in Patients with Pheochromocytoma.

Germline mutations occur in up to 30-40% of pheochromocytoma/paraganglioma, with mutations in the succinate dehydrogenase (SDH) subunits B (SDHB) and D (SDHD) being the most common. Blood samples are favored for obtaining high quality DNA, however, leukocytes can also be obtained by collecting saliva. The aim of this study was to determine whether SDHB and SDHD gene mutations in patients with pheochromocytoma/paraganglioma could be determined using a salivary sample. Paired blood and salivary samples were collected from 30 patients: 9 SDHB mutation positive, 13 with a SDHD mutation, and 8 without any SDHx mutations. The Oragene DISCOVER kit was used to collect and extract DNA from saliva. Blood DNA was extracted from EDTA blood samples. The DNA purification and concentration were measured by spectrophotometry. The 8 exons of SDHB and the 4 exons of SDHD were amplified and sequenced by PCR-based bidirectional Sanger sequencing. Total DNA yields from blood DNA were similar to those obtained from saliva DNA [mean (±SD) saliva vs. blood DNA concentration 514.6 (±580.8) ng/µl vs. 360.9 (±262.7) ng/µl; p=0.2)]. The purity of the saliva DNA samples was lower than that of blood [mean OD260/OD280 ratio 1.78 (±0.13) vs. 1.87 (±0.04); p=0.001, respectively], indicating more protein contamination in the saliva-extracted DNA. This study shows that salivary DNA collected from patients with pheochromocytoma/paraganglioma is a good alternative for extraction of genomic DNA for its high DNA concentration and acceptable purity and can be used as an alternative to blood derived DNA in screening for SDHB and SDHD mutations.

Diagnostic Value of Urinary Steroid Profiling in the Evaluation of Adrenal Tumors.

Radiological examination may unexpectedly reveal an adrenal mass. Current algorithms for differentiating between benign and malignant lesions mainly rely on size and densitometry on unenhanced CT, which have limited specificity. We examined the diagnostic value of urinary steroid profiling by gas chromatography/mass-spectrometry (GC/MS) in differentiating between benign and malignant adrenal tumors. A retrospective study in two referral centers for patients with adrenal disease was performed. All urinary steroid profiles ordered for evaluation of an adrenal tumor between January 2000 and November 2011 were examined. Patients were diagnosed with adrenal cortical carcinoma (ACC), adrenal cortical adenoma (ACA), or other adrenal mass. Results of hormonal measurements, imaging studies, pathology reports, and clinical outcome were retrieved from medical records. The diagnostic value of individual urinary steroid metabolites was determined by receiver operating characteristics analysis. Cut-off values were compared to reference values from an age and gender-standardized population of healthy controls. Eighteen steroid metabolites were excreted in significantly higher concentrations in patients with ACC (n = 27) compared to patients with ACA (n = 107) or other adrenal conditions (n = 18). Tetrahydro-11-deoxycortisol (THS) at a cut-off value of 2.35 µmol/24 h differentiated ACC from other adrenal disorders with 100% sensitivity and 99% specificity. Elevated urinary excretion of THS was associated with a very high sensitivity and specificity to differentiate between an ACC and a benign adrenal mass. Urinary steroid profiling might be a useful diagnostic test for the evaluation of patients with an adrenal incidentaloma.

Ion chromatography for the precise analysis of chloride and sodium in sweat for the diagnosis of cystic fibrosis.

BACKGROUND: Measurement of chloride in sweat is an essential part of the diagnostic algorithm for cystic fibrosis. The lack in sensitivity and reproducibility of current methods led us to develop an ion chromatography/high-performance liquid chromatography (IC/HPLC) method, suitable for the analysis of both chloride and sodium in small volumes of sweat. METHODS: Precision, linearity and limit of detection of an in-house developed IC/HPLC method were established. Method comparison between the newly developed IC/HPLC method and the traditional Chlorocounter was performed, and trueness was determined using Passing Bablok method comparison with external quality assurance material (Royal College of Pathologists of Australasia). RESULTS: Precision and linearity fulfill criteria as established by UK guidelines are comparable with inductively coupled plasma-mass spectrometry methods. Passing Bablok analysis demonstrated excellent correlation between IC/HPLC measurements and external quality assessment target values, for both chloride and sodium. With a limit of quantitation of 0.95 mmol/L, our method is suitable for the analysis of small amounts of sweat and can thus be used in combination with the Macroduct collection system. CONCLUSIONS: Although a chromatographic application results in a somewhat more expensive test compared to a Chlorocounter test, more accurate measurements are achieved. In addition, simultaneous measurements of sodium concentrations will result in better detection of false positives, less test repeating and thus faster and more accurate and effective diagnosis. The described IC/HPLC method, therefore, provides a precise, relatively cheap and easy-to-handle application for the analysis of both chloride and sodium in sweat.

Plasma levels of free metanephrines and 3-methoxytyramine indicate a higher number of biochemically active HNPGL than 24-h urinary excretion rates of catecholamines and metabolites.

CONTEXT: A substantial number of patients with head and neck paragangliomas (HNPGLs) have biochemically active tumors, evidenced by increased urinary excretion of catecholamines and metabolites, including 3-methoxytyramine (3MT). It is unclear whether plasma levels of these parameters are more sensitive to detect biochemical activity in HNPGL patients than urinary excretion rates. OBJECTIVE: To compare plasma free levels vs urinary excretion rates of deconjugated 3MT and combined metanephrines (MNs) in patients with HNPGL. PATIENTS AND METHODS: We included 124 consecutive patients with HNPGL for screening of catecholamine excess by measurement of 24-h urinary excretion rates of deconjugated (nor)metanephrine, (nor)epinephrine, dopamine, vanillylmandelic acid, 3MT, and plasma free levels of (nor)metanephrine and 3MT. RESULTS: Plasma free 3MT levels were increased in 35 of the 124 patients (28%), whereas 24-h urinary excretion of deconjugated 3MT was increased in 30 patients (24%) (P=0.13). Plasma free MN levels were increased in seven patients (6%) and urinary deconjugated MN levels in six patients (5%) (P=1.00). Plasma free normetanephrine (NMN) levels were increased in seven patients (6%), and five patients had increased urinary excretion of deconjugated NMN (4%) (P=0.69). Plasma free combined MN levels (NMN, MN, and 3MT) were increased in 41 patients (33%), whereas 24-h urinary excretion rates of deconjugated combined MNs were increased in 33 patients (27%, P<0.05). CONCLUSIONS: The combined levels of free MNs and free 3MT in plasma indicate a higher number of biochemically active HNPGLs than the 24-h urinary excretion rates of these markers.

Determinants of HbA1c in nondiabetic Dutch adults: genetic loci and clinical and lifestyle parameters, and their interactions in the Lifelines Cohort Study.

OBJECTIVES: Glycated haemoglobin (HbA1c) is associated with cardiovascular disease risk in individuals without diabetes, and its use has been recommended for diagnosing diabetes. Therefore, it is important to gain further understanding of the determinants of HbA1c. The aim of this study was to investigate the effects of genetic loci and clinical and lifestyle parameters, and their interactions, on HbA1c in nondiabetic adults. DESIGN: Population-based cohort study. SETTING: Three northern provinces of the Netherlands. SUBJECTS: A total of 2921 nondiabetic adults participating in the population-based LifeLines Cohort Study. MEASUREMENTS: Body mass index (BMI), waist circumference, HbA1c, fasting plasma glucose (FPG) and erythrocyte indices were measured. Data on current smoking and alcohol consumption were collected through questionnaires. Genome-wide genotyping was performed, and 12 previously identified single-nucleotide polymorphisms (SNPs) were selected for replication and categorized as 'glycaemic' and 'nonglycaemic' SNPs according to their presumed mechanism(s) of action on HbA1c. Genetic risk scores (GRSs) were calculated as the sum of the weighted effect of HbA1c-increasing alleles. RESULTS: Age, gender, BMI, FPG, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, current smoking and alcohol consumption were independent predictors of HbA1c, together explaining 26.2% of the variance in HbA1c, with FPG contributing 10.9%. We replicated three of the previously identified SNPs and the GRSs were also found to be independently associated with HbA1c. We found a smaller effect of the 'nonglycaemic GRS' in females compared with males and an attenuation of the effect of the GRS of all 12 SNPs with increasing BMI. CONCLUSIONS: Our results suggest that a substantial portion of HbA1c is determined by nonglycaemic factors. This should be taken into account when considering the use of HbA1c as a diagnostic test for diabetes.