Diurnal rhythms in the white adipose tissue transcriptome are disturbed in obese individuals with type 2 diabetes compared with lean control individuals

AIMS/HYPOTHESIS

Animal studies have indicated that disturbed diurnal rhythms of clock gene expression in adipose tissue can induce obesity and type 2 diabetes. The importance of the circadian timing system for energy metabolism is well established, but little is known about the diurnal regulation of (clock) gene expression in obese individuals with type 2 diabetes. In this study we aimed to identify key disturbances in the diurnal rhythms of the white adipose tissue transcriptome in obese individuals with type 2 diabetes.

METHODS

In a case-control design, we included six obese individuals with type 2 diabetes and six healthy, lean control individuals. All participants were provided with three identical meals per day for 3 days at zeitgeber time (ZT, with ZT 0:00 representing the time of lights on) 0:30, 6:00 and 11:30. Four sequential subcutaneous abdominal adipose tissue samples were obtained, on day 2 at ZT 15:30, and on day 3 at ZT 0:15, ZT 5:45 and ZT 11:15. Gene expression was measured using RNA sequencing.

RESULTS

The core clock genes showed reduced amplitude oscillations in the individuals with type 2 diabetes compared with the healthy control individuals. Moreover, in individuals with type 2 diabetes, only 1.8% (303 genes) of 16,818 expressed genes showed significant diurnal rhythmicity, compared with 8.4% (1421 genes) in healthy control individuals. Enrichment analysis revealed a loss of rhythm in individuals with type 2 diabetes of canonical metabolic pathways involved in the regulation of lipolysis. Enrichment analysis of genes with an altered mesor in individuals with type 2 diabetes showed decreased activity of the translation initiating pathway 'EIF2 signaling'. Individuals with type 2 diabetes showed a reduced diurnal rhythm in postprandial glucose concentrations.

CONCLUSIONS/INTERPRETATION

Diurnal clock and metabolic gene expression rhythms are decreased in subcutaneous adipose tissue of obese individuals with type 2 diabetes compared with lean control participants. Future investigation is needed to explore potential treatment targets as identified by our study, including clock enhancement and induction of EIF2 signalling.

DATA AVAILABILITY

The raw sequencing data and supplementary files for rhythmic expression analysis and Ingenuity Pathway Analysis have been deposited in NCBI Gene Expression Omnibus (GEO series accession number GSE104674).

Early thyroxine treatment in Down syndrome and thyroid function later in life

OBJECTIVE

The hypothalamus-pituitary-thyroid (HPT) axis set point develops during the fetal period and first two years of life. We hypothesized that thyroxine treatment during these first two years, in the context of a randomized controlled trial (RCT) in children with Down syndrome, may have influenced the HPT axis set point and may also have influenced the development of Down syndrome-associated autoimmune thyroiditis.

METHODS

We included 123 children with Down syndrome 8.7 years after the end of an RCT comparing thyroxine treatment vs placebo and performed thyroid function tests and thyroid ultrasound. We analyzed TSH and FT4 concentrations in the subgroup of 71 children who were currently not on thyroid medication and had no evidence of autoimmune thyroiditis.

RESULTS

TSH concentrations did not differ, but FT4 was significantly higher in the thyroxine-treated group than that in the placebo group (14.1 vs 13.0 pmol/L; P = 0.02). There was an increase in anti-TPO positivity, from 1% at age 12 months to 6% at age 24 months and 25% at age 10.7 years with a greater percentage of children with anti-TPO positivity in the placebo group (32%) compared with the thyroxine-treated group (18.5%) (P = 0.12). Thyroid volume at age 10.7 years (mean: 3.4 mL; range: 0.5-7.5 mL) was significantly lower (P < 0.01) compared with reference values (5.5 mL; range: 3-9 mL) and was similar in the thyroxine and placebo group.

CONCLUSION

Thyroxine treatment during the first two years of life led to a mild increase in FT4 almost 9 years later on and may point to an interesting new mechanism influencing the maturing HPT axis set point. Furthermore, there was a trend toward less development of thyroid autoimmunity in the thyroxine treatment group, suggesting a protective effect of the early thyroxine treatment. Lastly, thyroid volume was low possibly reflecting Down-specific thyroid hypoplasia.

Determination of human reference values for serum total 1,25-dihydroxyvitamin D using an extensively validated 2D ID-UPLC-MS/MS method

BACKGROUND

To assess a patient's vitamin D status the precursor metabolite 25-hydroxyvitamin D can be determined. However, measurement of 1,25-dihydroxyvitamin D is required when disorders of 1a-hydroxylation, extrarenal 1a-hydroxylation, or vitamin D receptor defects are suspected.

METHODS

The aim of this study was to determine reference values for 1,25-dihydroxyvitamin D₃ and D₂ using a 2D ID-UPLC-MS/MS method.

RESULTS

The LC-MS/MS method, able to measure picomolar concentrations of both 1,25-dihydroxyvitamin D₃ and D₂ in human serum, was extensively validated. Intra-assay variations were <5% and 8.5% and <7.5% and 11%, for 1,25-dihydroxyvitamin D₃ and D₂, respectively, over the whole dynamic range (3.1-376 and 3.1-652pmol/L). Limit of quantitation was 3.4pmol/L for both compounds. Our method correlated well with a published LC-MS/MS method (r=0.87) and with the average 1,25-dihydroxyvitamin D₃ results of the vitamin D External Quality Assessment Scheme (DEQAS) determined with LC-MS/MS (r=0.93). Reference ranges, determined in 96 plasma samples of healthy volunteers were 59-159pmol/L and <17pmol/L for respectively 1,25-dihydroxyvitamin D₃ and D₂. The female part of the reference group showed a statistically significant decrease of 1,25-dihydroxyvitamin D₃ concentrations with age. The presence of significantly higher average 1,25-dihydroxyvitamin D₃ levels in premenopausal women taking oral contraceptive pills compared to postmenopausal women suggests that this effect is estrogen-related, as estrogens lead to a higher vitamin D binding protein.

CONCLUSIONS

The major finding of the present study is a reference interval of 59-159pmol/L for 1,25-dihydroxyvitamin D₃ determined with a highly sensitive and precise LC-MS/MS method.

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

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

Predicting the Risk of Recurrence Before the Start of Antithyroid Drug Therapy in Patients With Graves' Hyperthyroidism

Genotyping increases the accuracy of a clinical score (based on pretreatment age, goiter size, FT4, TBII) for predicting recurrence of Graves' hyperthyroidism after a course of antithyroid drugs: a prospective study.

The Hypercoagulable state in Hyperthyroidism is mediated via the Thyroid Hormone β Receptor pathway

OBJECTIVE

Hyperthyroidism is associated with a hypercoagulable state, but the underlying mechanism is unknown. Patients with resistance to thyroid hormone (RTH) due to defective thyroid hormone receptor β (TRβ) exhibit elevated circulating thyroid hormones (TH) with refractoriness to TH action in TRβ-expressing tissues. We tested the hypothesis that the hypercoagulable state in hyperthyroidism is mediated via the TRβ.

DESIGN

We conducted a cross-sectional study from November 2013 to January 2015 in 3 hospitals in the Netherlands and the United Kingdom.

METHODS

Patients with RTH due to defective TRβ (n=18), patients with hyperthyroidism (n=16) and euthyroid subjects (n=18) were included. TH concentrations and markers of coagulation and fibrinolysis were measured. Data are expressed as median [interquartile range].

RESULTS

Free thyroxine (FT4) levels were slightly higher in hyperthyroid patients than in RTH patients (53.9 [30.5-70.0] and 34.9 [28.4-42.2]pmol/l, respectively, P=0.042). Both groups had raised FT4 levels compared to euthyroid subjects (14.0 [13.0-15.8] pmol/l, P≤0.001). Levels of von Willebrand factor (VWF), factor (F) VIII, fibrinogen, and D-dimer were significantly higher in hyperthyroid patients than in RTH patients (VWF 231 [195-296] vs. 111 [82-140]%, FVIII 215 [192-228] vs. 145 [97-158]%, fibrinogen 3.6 [3.0-4.4] vs. 2.8 [2.5-3.2]g/L, D-dimer 0.41 [0.31-0.88] vs. 0.20 [0.17-0.26]mg/L, respectively, P≤0.001), while there were no differences between RTH patients and euthyroid controls.

CONCLUSIONS

Parameters of coagulation and fibrinolysis were elevated in hyperthyroid patients compared to patients with RTH due to defective TRβ, whereas these parameters were not different between euthyroid controls and RTH patients, despite elevated FT4 concentrations in RTH patients. This indicates that the procoagulant effects observed in hyperthyroidism are mediated via the TRβ.

Clonidine increases bone resorption in humans

SUMMARY

Inhibition of sympathetic signaling to bone reduces bone resorption in rodents. In contrast, we show that pharmacological reduction of the sympathetic tone increases bone resorption in humans in vivo. This effect does not appear to be mediated via a direct pharmacological effect on the osteoclast.

INTRODUCTION

Inhibition of sympathetic signaling to bone reduces bone resorption in rodents. It is uncertain whether a similar role for the sympathetic nervous system exists in humans. The sympathetic tone can be reduced by clonidine, which acts via alpha-2-adrenergic receptors in the brainstem. Our objective was to determine the effect of clonidine on bone turnover in humans.

METHODS

The acute effect of a single oral dose of 0.3 mg clonidine on serum bone turnover markers (C-terminal cross-linking telopeptides of collagen type I (CTx), a marker for bone resorption, and procollagen type 1 N propeptide (P1NP), a marker for bone formation) was determined in a randomized crossover design in 12 healthy volunteers, aged 18-70 years. In addition, we assessed the effect of clonidine on the number of tartrate-resistant acid phosphatase-positive multinucleated cells (TRAcP(+) MNCs) and bone resorption.

RESULTS

CTx concentrations increased after clonidine treatment compared to the control condition (p = 0.035). P1NP concentrations were not affected by clonidine (p = 0.520). In vitro, clonidine had no effect on the number of TRAcP(+) MNCs (p = 0.513) or on bone resorption (p = 0.996).

CONCLUSIONS

We demonstrated that clonidine increases bone resorption in humans in vivo. This effect does not appear to be mediated via a direct effect on the osteoclast.

Rapid effects of deep brain stimulation reactivation on symptoms and neuroendocrine parameters in obsessive-compulsive disorder

Improvement of obsessions and compulsions by deep brain stimulation (DBS) for obsessive-compulsive disorder (OCD) is often preceded by a rapid and transient mood elevation (hypomania). In a previous study we showed that improvement of mood by DBS for OCD is associated with a decreased activity of the hypothalamus-pituitary adrenal axis. The aim of our present study was to evaluate the time course of rapid clinical changes following DBS reactivation in more detail and to assess their association with additional neuroendocrine parameters. We included therapy-refractory OCD patients treated with DBS (>1 year) and performed a baseline assessment of symptoms, as well as plasma concentrations of thyroid-stimulating hormone (TSH), prolactin, growth hormone, copeptin and homovanillic acid. This was repeated after a 1-week DBS OFF condition. Next, we assessed the rapid effects of DBS reactivation by measuring psychiatric symptom changes using visual analog scales as well as repeated neuroendocrine measures after 30 min, 2 h and 6 h. OCD, anxiety and depressive symptoms markedly increased during the 1-week OFF condition and decreased again to a similar extent already 2 h after DBS reactivation. We found lower plasma prolactin (41% decrease, P=0.003) and TSH (39% decrease, P=0.003) levels during DBS OFF, which increased significantly already 30 min after DBS reactivation. The rapid and simultaneous increase in TSH and prolactin is likely to result from stimulation of hypothalamic thyrotropin-releasing hormone (TRH), which may underlie the commonly observed transient mood elevation following DBS.

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.

Short-Term Effect of Estrogen on Human Bone Marrow Fat

Bone marrow fat, an unique component of the bone marrow cavity increases with aging and menopause and is inversely related to bone mass. Sex steroids may be involved in the regulation of bone marrow fat, because men have higher bone marrow fat than women and clinical observations have suggested that the variation in bone marrow fat fraction is greater in premenopausal compared to postmenopausal women and men. We hypothesized that the menstrual cycle and/or estrogen affects the bone marrow fat fraction. First, we measured vertebral bone marrow fat fraction with Dixon Quantitative Chemical Shift MRI (QCSI) twice a week during 1 month in 10 regularly ovulating women. The vertebral bone marrow fat fraction increased 0.02 (95% CI, 0.00 to 0.03) during the follicular phase (p = 0.033), and showed a nonsignificant decrease of 0.02 (95% CI, -0.01 to 0.04) during the luteal phase (p = 0.091). To determine the effect of estrogen on bone marrow fat, we measured vertebral bone marrow fat fraction every week for 6 consecutive weeks in 6 postmenopausal women before, during, and after 2 weeks of oral 17-β estradiol treatment (2 mg/day). Bone marrow fat fraction decreased by 0.05 (95% CI, 0.01 to 0.09) from 0.48 (95% CI, 0.42 to 0.53) to 0.43 (95% CI, 0.34 to 0.51) during 17-β estradiol administration (p < 0.001) and increased again after cessation. During 17-β estradiol administration the bone formation marker procollagen type I N propeptide (P1NP) increased (p = 0.034) and the bone resorption marker C-terminal crosslinking telopeptides of collagen type I (CTx) decreased (p < 0.001). In conclusion, we described the variation in vertebral bone marrow fat fraction among ovulating premenopausal women. And among postmenopausal women, we demonstrated that 17-β estradiol rapidly reduces the marrow fat fraction, suggesting that 17-β estradiol regulates bone marrow fat independent of bone mass.

The water deprivation test and a potential role for the arginine vasopressin precursor copeptin to differentiate diabetes insipidus from primary polydipsia

The water deprivation test is the gold standard test to differentiate central or nephrogenic diabetes insipidus (DI) from primary polydipsia (PP) in patients with polyuria and polydipsia. Few studies have addressed the diagnostic performance of this test. The aim of this retrospective cohort study was to evaluate the diagnostic performance of the standard water deprivation test, including plasma arginine vasopressin (AVP) measurements, in 40 consecutive patients with polyuria. We compared initial test results with the final clinical diagnosis, i.e., no DI, central DI, or nephrogenic DI. The median length of follow-up was 8 years. In a subset of ten patients, the novel marker copeptin (CP) was measured in plasma. Using the final diagnosis as a gold standard, a threshold for urine osmolality of >800 mOsmol/kg after water deprivation yielded a sensitivity and specificity of 96 and 100%, respectively, for diagnosing PP. Sensitivity increased to 100% if the cut-off value for urine osmolality was set at 680 mOsmol/kg. Plasma AVP levels did not differ between patient groups and did not differentiate among central DI, nephrogenic DI, or PP. In all three patients with central DI, plasma CP was <2.5 pmol/l with plasma osmolality >290 mOsmol/kg, and >2.5 pmol/l in patients without DI. The optimal cut-off value for differentiating PP from DI during a water deprivation test was urine osmolality >680 mOsmol/kg. Differentiating between central and nephrogenic DI should be based on clinical judgment as AVP levels did not discriminate.

The effects of beta-2 adrenergic agonist and antagonist on human bone metabolism: a randomized controlled trial

PURPOSE

Genetic knockout or pharmacological inhibition of the beta-2 adrenergic receptor (B2AR) increased bone mass, whereas stimulation decreased bone mass in rodents. In humans, observational studies support sympathetic nervous system regulation of bone metabolism, but intervention studies are lacking. We aimed to determine the effects of a selective beta-2 adrenergic agonist and non-selective antagonist on human bone metabolism.

METHODS

32 healthy postmenopausal women were included in a randomized controlled trial conducted in the Academic Medical Center Amsterdam. Participants were randomized to receive treatment with 17-β estradiol 2mg/day; 17-β estradiol 2mg/day and terbutaline 5mg/day (selective B2AR agonist); propranolol 80mg/day (non-selective B-AR antagonist); or no treatment during 12weeks. Main outcome measure was the change in serum concentrations of procollagen type I N propeptide (P1NP) and C-terminal crosslinking telopeptides of collagen type I (CTx) as markers of bone formation and resorption after 12weeks compared between the treatment groups. Data were analyzed with mixed model analysis.

RESULTS

17-β estradiol decreased bone turnover compared to control (P1NP p<0.001, CTx p=0.003), but terbutaline combined with 17-β estradiol failed to increase bone turnover compared to 17-β estradiol alone (P1NP p=0.135, CTx p=0.406). Propranolol did not affect bone turnover compared to control (P1NP p=0.709, CTx p=0.981).

CONCLUSION

Selective beta-2 adrenergic agonists and non-selective beta-antagonists do not affect human bone turnover although we cannot exclude small changes below the detection limit of this study.

Selenite supplementation in euthyroid subjects with thyroid peroxidase antibodies

CONTEXT

Euthyroid thyroid peroxidase (TPO-Ab)-positive subjects are at risk for progression to subclinical and overt autoimmune hypothyroidism. Previous studies have shown a decrease in TPO-Ab and improvement of quality-of-life (QoL) in L-T4-treated hypothyroid patients upon selenium supplementation.

OBJECTIVES

To evaluate in euthyroid TPO-Ab-positive women without thyroid medication whether selenite decreases TPO-Ab and improves QoL.

DESIGN

Randomized, placebo-controlled, double-blind study.

PATIENTS AND METHODS

Euthyroid (TSH 0·5-5·0 mU/l, FT4 10-23 pm) women with TPO-Ab ≥ 100 kU/l were randomized to receive 200 mcg sodium selenite daily (n = 30) or placebo (n = 31) for 6 months. TSH, FT4, TPO-Ab, selenium (Se), selenoprotein P (SePP) and QoL were measured at baseline, 3, 6 and 9 months.

RESULTS

There were no differences in baseline characteristics between the Se group and the placebo group. During selenite supplementation, serum Se and SePP did not change in the placebo group, but increased in the Se group. TPO-Ab and TSH did not change significantly in any group. TPO-Ab in the Se group were 895 (130-6800) at baseline, 1360 (60-7050) kU/l at 6 months, in the placebo group 1090 (120-9200) and 1130 (80-9900) kU/l, respectively (median values with range). TSH in the Se group was 2·1 (0·5-4·3) at baseline, 1·7 (0·0-5·3) mU/l at 6 months, in the placebo group 2·4 (0·7-4·4) and 2·5 (0·2-4·3) mU/l, respectively. QoL was not different between the groups.

CONCLUSION

Six months selenite supplementation increased markers of selenium status but had no effect on serum TPO-Ab, TSH or quality-of-life in euthyroid TPO-Ab-positive women.

Thyrotropin secretion in healthy subjects is robust and independent of age and gender, and only weakly dependent on body mass index

CONTEXT

Studies of the influence of sex, age, and body weight on TSH secretion are not unanimous. Most reports are based on a single TSH measurement; studies using frequent blood sampling are scarce and include a limited number of selected subjects.

OBJECTIVE

The goal was to investigate TSH dynamics in 117 healthy adults.

METHODS

TSH was measured by a sensitive immunofluorometric assay. Secretion parameters were quantified by automated deconvolution, approximate entropy [ApEn], spikiness, and diurnal properties.

RESULTS

Mean age was 43 years (range, 22-77 y). Mean body mass index (BMI) was 26.8 kg/m(2) (range, 18.3-39.4 kg/m(2)). Daily TSH secretion was 45.4 mU/L (range, 8.0-207 mU/L). There were no sex differences in secretion parameters, including pulse frequency; basal, pulsatile, and total secretion; pulse mode; half life; pulse regularity; ApEn; spikiness; and nycthemeral properties. BMI was positively related to basal secretion. Total secretion correlated negatively with free T₄ (R = 0.225; P = .018). The onset of the nocturnal surge was delayed by increasing BMI and advanced by increasing age. ApEn and spikiness correlated positively with age, especially in men. The 9 am sample correlated strongly with the total 24-hour secretion, explaining two-thirds of the variability.

CONCLUSION

This study shows that the 24-hour TSH secretion in healthy volunteers is stable and robust and not influenced by sex, BMI, and age. ApEn in the elderly, especially men, is increased, pointing to a less tight feedback control. Furthermore, aging is associated with advance shifting of the TSH rhythm, which is a phenomenon also observed in other biological rhythms.

The IGSF1 deficiency syndrome: characteristics of male and female patients

CONTEXT

Ig superfamily member 1 (IGSF1) deficiency was recently discovered as a novel X-linked cause of central hypothyroidism (CeH) and macro-orchidism. However, clinical and biochemical data regarding growth, puberty, and metabolic outcome, as well as features of female carriers, are scarce.

OBJECTIVE

Our objective was to investigate clinical and biochemical characteristics associated with IGSF1 deficiency in both sexes.

METHODS

All patients (n = 42, 24 males) from 10 families examined in the university clinics of Leiden, Amsterdam, Cambridge, and Milan were included in this case series. Detailed clinical data were collected with an identical protocol, and biochemical measurements were performed in a central laboratory.

RESULTS

Male patients (age 0-87 years, 17 index cases and 7 from family studies) showed CeH (100%), hypoprolactinemia (n = 16, 67%), and transient partial GH deficiency (n = 3, 13%). Pubertal testosterone production was delayed, as were the growth spurt and pubic hair development. However, testicular growth started at a normal age and attained macro-orchid size in all evaluable adults. Body mass index, percent fat, and waist circumference tended to be elevated. The metabolic syndrome was present in 4 of 5 patients over 55 years of age. Heterozygous female carriers (age 32-80 years) showed CeH in 6 of 18 cases (33%), hypoprolactinemia in 2 (11%), and GH deficiency in none. As in men, body mass index, percent fat, and waist circumference were relatively high, and the metabolic syndrome was present in 3 cases.

CONCLUSION

In male patients, the X-linked IGSF1 deficiency syndrome is characterized by CeH, hypoprolactinemia, delayed puberty, macro-orchidism, and increased body weight. A subset of female carriers also exhibits CeH.

Deep brain stimulation for obsessive-compulsive disorder is associated with cortisol changes

Deep brain stimulation (DBS) is an effective treatment for obsessive-compulsive disorder (OCD), but its mechanism of action is largely unknown. Since DBS may induce rapid symptomatic changes and the pathophysiology of OCD has been linked to the hypothalamic-pituitary-adrenal (HPA) axis, we set out to study whether DBS affects the HPA axis in OCD patients. We compared a stimulation ON and OFF condition with a one-week interval in 16 therapy-refractory OCD patients, treated with DBS for at least one year, targeted at the nucleus accumbens (NAc). We measured changes in 24-h urinary excretion of free cortisol (UFC), adrenaline and noradrenaline and changes in obsessive-compulsive (Y-BOCS), depressive (HAM-D) and anxiety (HAM-A) symptom scores. Median UFC levels increased with 53% in the OFF condition (from 93 to 143nmol/24h, p=0.12). There were no changes in urinary adrenaline or noradrenaline excretion. The increase in Y-BOCS (39%), and HAM-D (78%) scores correlated strongly with increased UFC levels in the OFF condition. Our findings indicate that symptom changes following DBS for OCD patients are associated with changes in UFC levels.

Brain natriuretic peptide is not predictive of dilated cardiomyopathy in Becker and Duchenne muscular dystrophy patients and carriers

Background

Cardiomyopathy is reported in Duchenne and Becker muscle dystrophy patients and female carriers. Brain Natriuretic peptide (BNP) is a hormone produced mainly by ventricular cardiomyocytes and its production is up regulated in reaction to increased wall stretching. N-terminal-proBNP (NT-proBNP) has been shown to be a robust laboratory parameter to diagnose and monitor cardiac failure, and it may be helpful to screen for asymptomatic left ventricular dysfunction. Therefore we tested whether NT-proBNP can distinguish patients with Duchenne or Becker muscular dystrophy patients and carriers of a dystrophin mutation with a dilated cardiomyopathy from those without.

Methods

In a cohort of Duchenne and Becker muscle dystrophy patients (n = 143) and carriers (n = 219) NT-proBNP was measured, and echocardiography was performed to diagnose dilated cardiomyopathy (DCM).

Results

In total sixty-one patients (17%) fulfilled the criteria for DCM, whereas 283 patients (78%) had an elevated NT-pro BNP. The sensitivity of NT-proBNP for DCM in patients or carriers was 85%, the specificity 23%, area under the ROC-curve = 0.56. In the specified subgroups there was also no association.

Conclusion

Measurement of NT-pro BNP in patients suffering from Duchenne or Becker muscular dystrophy and carriers does not distinguish between those with and without dilated cardiomyopathy.

Measuring free thyroxine levels in neonatal heel-prick samples

The Dutch neonatal screening scheme for Congenital Hypothyroidism (CH) is primarily based on the determination of thyroxine (T4) in filter paper blood spots. In the lowest 5% of T4 values, thyroxine binding globulin (TBG) is measured in order to be able to correct for occasional low TBG levels. However, because the commercial TBG kit has been withdrawn from the market, alternative strategies are needed to be explored including the assessment of free T4. We evaluated the Neonatal Free Thyroxine (fT4) enzyme immunoassay (EIA) kit of Bio-Rad. FT4 as measured in a daily run of random samples correlated with T4. We also observed a correlation between fT4 and T4, and between fT4 and T4/TBG ratio in blood spots with low T4 concentrations. The correlation between fT4 and T4 in blood spots of proven CH-patients was highly significant. ROC curves were constructed for the fT4 assay and the T4/TBG ratio based on 27 CH patients and 215 controls with a complete set of data. The curves of both assays seemed to be rather similar. We conclude that the validity of the fT4 and the T4/TBG-approach seems to be the same. A study with a larger sample size giving the same or even more favorable results for the fT4-approach is necessary before we will change the present CH protocol.

Effects of a hypercaloric diet on β-cell responsivity in lean healthy men

OBJECTIVE

Insulin resistance and hyperinsulinaemia precede the onset of obesity-induced DM2. The early adaptation of the β-cell during the initial phase of overfeeding and weight gain has only been partly elucidated. We studied the early changes in insulin clearance and β-cell responsivity during a positive and negative energy balance in lean healthy men.

DESIGN

We studied in nine healthy lean men [age, 37 (27-43) years; BMI, 23·6 (20·6-25·6) kg/m(2) ] insulin sensitivity, insulin clearance, insulin secretion and static and dynamic β-cell responsivity at baseline and after the hypercaloric and subsequent hypocaloric diet.

RESULTS

Participants gained 7 [5·1-7·6]% of their initial body weight on the hypercaloric diet. Compared to baseline, insulin sensitivity and insulin clearance decreased, while glucose-stimulated insulin secretion was higher. The GLP-1 response to oral glucose did not change. The dynamic β-cell responsivity index increased but the basal and static responsivity indexes did not change. Total and static disposition indexes (DIs) in the hypercaloric state showed a trend towards a decrease. During the hypocaloric diet, insulin sensitivity, glucose-stimulated insulin secretion and insulin clearance returned to baseline. The responsivity and the DIs were not different in the hypocaloric phase compared to baseline.

CONCLUSION

A positive energy balance resulting in weight gain in lean men induces hyperinsulinaemia, which is explained by a combined effect on insulin clearance and insulin secretion. Increased insulin secretion was related to insulin resistance-induced higher glucose concentrations but also to increased dynamic β-cell responsivity. Glucose sensitivity of the β-cell did not change. These early adaptations are completely reversible during a negative energy balance after loss of the gained weight.

Genotypes in relation to phenotypic appearance and exposure to environmental factors in Graves' hyperthyroidism

BACKGROUND

Genetic polymorphisms and environmental factors are both involved in the pathogenesis of Graves' disease, but their interaction and effect on Graves' phenotypes have scarcely been investigated.

OBJECTIVE

To test the hypothesis that subjects with susceptibility genotypes develop more severe Graves' hyperthyroidism at a younger age and after less exposure to environmental factors, with attention to gender differences.

STUDY DESIGN

A prospective observational multicenter study in 205 adult Caucasian patients with untreated first episode of Graves' hyperthyroidism.

METHODS

Evaluation of genotypes (HLA DRB1*03, DQA1*05, DQB1*02; CTLA4 49A/G, CT60 A/G; PTPN22 C/T) in relation to phenotypes (age, sex, severity (clinical, biochemical, and immunological)) of hyperthyroidism and environmental factors (smoking, stress questionnaires).

RESULTS

G-alleles in CTLA4 single nucleotide polymorphisms were dose-dependently associated with younger age at the time of diagnosis and less exposure to daily hassles. In gender-specific analysis, this association is enhanced in men and attenuated in women. Males (but not females) in HLA linkage disequilibrium had more severe (biochemical and immunological) hyperthyroidism and a tendency to younger age at diagnosis, compared with those not in linkage disequilibrium.

CONCLUSION

Graves' hyperthyroidism occurs at a younger age with less exposure to environmental factors in subjects carrying susceptibility genotypes. The impact of genotypes seems to be greater in males than in females.

Bone resorption is increased in pheochromocytoma patients and normalizes following adrenalectomy

CONTEXT

The sympathetic nervous system (SNS) controls bone turnover in rodents, but it is uncertain whether a similar role for the SNS exists in humans. Pheochromocytomas are catecholamine-producing neuroendocrine tumors. Because catecholamines are the neurotransmitters of the SNS, we hypothesized that pheochromocytoma patients have increased bone turnover.

OBJECTIVE

Our objective was to compare bone turnover in pheochromocytoma patients and controls.

DESIGN AND SETTING

This retrospective case-control study was performed at the Endocrine Department of the Academic Medical Center of the University of Amsterdam in The Netherlands from 2007 until 2011.

PATIENTS

All patients were screened for pheochromocytoma. Cases (n = 21) were identified by 24-h urinary excretion of fractionated metanephrines above the institutional reference value and confirmed by histology after adrenalectomy. All patients screened and diagnosed as not having pheochromocytoma served as controls (n = 126).

MAIN OUTCOME MEASURE

The difference in bone turnover markers C-terminal cross-linking telopeptides of collagen type I (CTx) and procollagen type 1 N propeptide (P1NP) between cases and controls was the main outcome measure.

RESULTS

CTx concentrations were higher in cases [343 ng/liter; interquartile range (IQR), 295 ng/liter] than in controls (232 ng/liter; IQR, 168 ng/liter; P < 0.001) and decreased after adrenalectomy [before, 365 ng/liter (IQR, 450 ng/liter); after, 290 ng/liter (IQR, 241 ng/liter); P = 0.044]. The effect remained after adjustment for possible confounders. P1NP concentrations did not differ.

CONCLUSIONS

This study shows that pheochromocytoma patients have increased bone resorption, which normalizes after adrenalectomy. This finding supports the concept of regulation of bone remodeling by the SNS in humans.

Circadian rhythms in the hypothalamo-pituitary-adrenal (HPA) axis

The pronounced daily variation in the release of adrenal hormones has been at the heart of the deciphering and understanding of the circadian timing system. Indeed, the first demonstration of an endocrine day/night rhythm was provided by Pincus (1943), by showing a daily pattern of 17-keto-steroid excretion in the urine of 7 healthy males. Twenty years later the adrenal gland was one of the very first organs to show, in vitro, that circadian rhythmicity was maintained. In the seventies, experimental manipulation of the daily corticosterone rhythm served as evidence for the identification of respectively the light- and food-entrainable oscillator. Another 20 years later the hypothalamo-pituitary-adrenal (HPA)-axis was key in furthering our understanding of the way in which rhythmic signals generated by the central pacemaker in the hypothalamic suprachiasmatic nuclei (SCN) are forwarded to the rest of the brain and to the organism as a whole. To date, the adrenal gland is still of prime importance for understanding how the oscillations of clock genes in peripheral tissues result in functional rhythms of these tissues, whereas it has become even more evident that adrenal glucocorticoids are key in the resetting of the circadian system after a phase-shift. The HPA-axis thus still is an excellent model for studying the transmission of circadian information in the body.

Treatment of amiodarone-induced thyrotoxicosis type 2: a randomized clinical trial

CONTEXT

Amiodarone-induced thyrotoxicosis (AIT) type 2 is self-limiting in nature, but most physicians are reluctant to continue amiodarone. When prednisone fails to restore euthyroidism, possibly due to mixed cases of AIT type 1 and 2, perchlorate (ClO(4)) might be useful because ClO(4) reduces the cytotoxic effect of amiodarone on thyrocytes.

OBJECTIVES

Our objectives were to demonstrate the feasibility of continuation of amiodarone in AIT type 2 and to evaluate the usefulness of ClO(4) (given alone or in combination with prednisone) in AIT type 2.

DESIGN AND SETTING

A randomized multicenter study was conducted in 10 Dutch hospitals.

METHODS

Patients with AIT type 2 were randomized to receive prednisone 30 mg/d (group A, n = 12), sodium perchlorate 500 mg twice daily (group B, n = 14), or prednisone plus perchlorate (group C, n = 10); all patients continued amiodarone and were also treated with methimazole 30 mg/d. Follow-up was 2 yr.

MAIN OUTCOME MEASURES

Treatment efficacy (defined as TSH values ≥ 0.4 mU/liter under continuation of amiodarone) and recurrent thyrotoxicosis were evaluated.

RESULTS

Initial therapy was efficacious in 100, 71, and 100% of groups A, B, and C, respectively (P = 0.03). The 29% failures in group B became euthyroid after addition of prednisone. Neither the time to reach TSH of 0.4 mU/liter or higher [8 wk (4-20), 14 wk (4-32), and 12 wk (4-28) in groups A, B, and C respectively] nor the time to reach free T(4) of 25 pmol/liter or below [4 wk (4-20), 12 wk (4-20), and 8 wk (4-20) in groups A, B, and C) were significantly different between groups (values as median with range). Recurrent thyrotoxicosis occurred in 8.3%.

CONCLUSION

Euthyroidism was reached despite continuation of amiodarone in all patients. Prednisone remains the preferred treatment modality of AIT type 2, because perchlorate given alone or in combination with prednisone had no better outcomes.

Familial neurohypophyseal diabetes insipidus due to a novel mutation in the arginine vasopressin-neurophysin II gene

BACKGROUND

Familial neurohypophyseal (central) diabetes insipidus (DI) is caused by mutations in the arginine vasopressin-neurophysin II (AVP-NPII) gene. The majority of cases is inherited in an autosomal dominant way. In this study, we present the clinical features of a mother and her son with autosomal dominant neurohypophyseal DI caused by a novel mutation.

CASE

A thirty-four-year-old woman and her three-year-old son were evaluated because of polyuria and polydipsia since the age of 1.5 years onwards. Both patients were subjected to a water deprivation test confirming the diagnosis of central DI. Magnetic resonance imaging of the brain of the mother showed a hypothalamus without apparent abnormalities and a relatively small neurohypophysis without a hyperintense signal. Mutation analysis showed a c.322G>T (p.?/p.Glu108X) in Exon 2 of the AVP-NPII gene in both mother and son.

DISCUSSION

This study reports neurohypophyseal DI in a mother and her son due to a novel mutation in Exon 2 of the AVP-NPII gene. Clinical and pathophysiological aspects of this disease are shortly reviewed and discussed.

Interference by antiruthenium antibodies in the Roche thyroid-stimulating hormone assay

There are many causes of interference in immunoassays causing erratic patient results. A method-specific interference due to antiruthenium antibodies in Roche free thyroxine (fT4) and free triiodothyronine (fT3) assays has been described previously. As a result, a new generation fT4 assay has been introduced by Roche. We describe six cases of interference due to antiruthenium antibodies, where in four cases interference in the Roche thyroid-stimulating hormone (TSH) assay was found as well. This raised the question as to whether other assays on this platform would also give incorrect results in patients with antiruthenium antibodies. Interference due to antiruthenium antibodies was suspected because of discrepancies between clinical presentation and/or TSH, fT4 and fT3 results. Samples of these six patients were re-analysed in Roche Diagnostics Laboratory, where it was demonstrated that the found discrepancies were indeed caused by interfering antiruthenium antibodies. Subsequently, these patients were asked to donate some blood once more for further evaluation, and three subjects agreed to participate. Their plasma was used to assay 18 analytes on Modular E and on a ruthenium-independent platform. The results were compared taking into account the known differences between distinct methods. As expected, significant interference was found in TSH. Also, in the new generation fT4 assay, ruthenium-induced interference was still present. However, the other assays, both competitive and immunometric, did not show clear interference. We therefore conclude that although antiruthenium antibodies theoretically can interfere in all assays on the Modular E platform, this kind of interference is found in the thyroid hormone assays, without marked interference in the other assays.

Erythrocyte glutathione concentration and production during hyperinsulinemia, hyperglycemia, and endotoxemia in healthy humans

In diabetes mellitus and sepsis, low erythrocyte glutathione (GSH) concentrations are found. Whether this is caused by lowered GSH production has not been clarified. To obtain insight in the relationship between erythrocyte GSH concentrations and GSH production, GSH kinetics were measured in healthy male volunteers during 4 different clamps (low-dose or medium-dose insulin [100 or 400 pmol/L] and euglycemia or hyperglycemia [5 or 12 mmol/L]) in a control setting (n = 6; all 4 clamps in the same subject) or after systemic administration of lipopolysaccharide (to mimic sepsis) (4 groups of n = 6; each clamp in a different subject). Hyperinsulinemia decreased erythrocyte GSH concentration (P = .042), but did not affect fractional synthetic rate (FSR) of GSH. Hyperglycemia did not affect erythrocyte GSH concentration, but decreased FSR of GSH (P = .025). Lipopolysaccharide decreased erythrocyte GSH concentration (P < .001), but increased FSR of erythrocyte GSH (P = .035). Depending on the metabolic circumstances, we found either stable GSH concentrations with lower production rates or decreased levels with either no change or an increase in production rate. Based upon these data, it seems inappropriate to infer conclusions about changes in synthesis rate of GSH from changes in its concentration.

Acute stress elicited by bungee jumping suppresses human innate immunity

Although a relation between diminished human immunity and stress is well recognized both within the general public and the scientific literature, the molecular mechanisms by which stress alters immunity remain poorly understood. We explored a novel model for acute human stress involving volunteers performing a first-time bungee jump from an altitude of 60 m and exploited this model to characterize the effects of acute stress in the peripheral blood compartment. Twenty volunteers were included in the study; half of this group was pretreated for 3 d with the β-receptor blocking agent propranolol. Blood was drawn 2 h before, right before, immediately after and 2 h after the jump. Plasma catecholamine and cortisol levels increased significantly during jumping, which was accompanied by significantly reduced ex vivo inducibility of proinflammatory cytokines as well as activation of coagulation and vascular endothelium. Kinome profiles obtained from the peripheral blood leukocyte fraction contained a strong noncanonical glucocorticoid receptor signal transduction signature after jumping. In apparent agreement, jumping down-regulated Lck/Fyn and cellular innate immune effector function (phagocytosis). Pretreatment of volunteers with propranolol abolished the effects of jumping on coagulation and endothelial activation but left the inhibitory effects on innate immune function intact. Taken together, these results indicate that bungee jumping leads to a catecholamine-independent immune suppressive phenotype and implicate noncanonical glucocorticoid receptor signal transduction as a major pathway linking human stress to impaired functioning of the human innate immune system.

Extended metabolic evaluation of suspected symptomatic hypoglycemia: the prolonged fast and beyond

The diagnostic evaluation of spontaneous hypoglycemia in adults is mainly directed at detecting an insulinoma. Its interpretation is troublesome in those patients who develop low venous plasma glucose levels with appropriate hypoinsulinemia during a prolonged supervised fast. In this study, we investigated in this group of patients whether abnormalities in intermediary metabolism (fatty acid oxidation and amino/organic acids) could be detected that might explain the hypoinsulinemic hypoglycemia. Ten patients with otherwise unexplained low venous plasma glucose levels (<3 mmol/L) during prolonged fasting were included in the study. The patients participated in an extended metabolic protocol based on stable isotope techniques after an overnight fast to explore abnormalities in endogenous glucose production and intermediary metabolism. Endogenous glucose production, glucoregulatory hormones, plasma acylcarnitines, gluconeogenic amino acids, and rates of fatty acid and carbohydrate oxidation after 16 and 22 hours of fasting were measured. Although during the prolonged fast all patients had low venous plasma glucose level, there were no hypoglycemic events during the extended metabolic protocol. No abnormalities in endogenous glucose production (compared with reference values obtained in young healthy volunteers), fatty acid oxidation, or amino acid/organic acids were found in this patient group. In a group of patients exhibiting low venous plasma glucose levels during prolonged fasting in whom insulinoma was excluded, we found no signs of metabolic disorders. Therefore, the observation of low plasma glucose values in this subgroup of patients probably does not warrant extensive metabolic evaluation.

An online solid-phase extraction-liquid chromatography-tandem mass spectrometry method to study the presence of thyronamines in plasma and tissue and their putative conversion from 13C6-thyroxine

Thyronamines are exciting new players at the crossroads of thyroidology and metabolism. Here, we report the development of a method to measure 3-iodothyronamine (T(1)AM) and thyronamine (T(0)AM) in plasma and tissue samples. The detection limit of the method was 0.25 nmol/l in plasma and 0.30 pmol/g in tissue both for T(1)AM and for T(0)AM. Using this method, we were able to demonstrate T(1)AM and T(0)AM in plasma and liver from rats treated with synthetic thyronamines. Although we demonstrated the in vivo conversion of (13)C(6)-thyroxine ((13)C(6)-T(4)) to (13)C(6)-3,5,3'-triiodothyronine, we did not detect (13)C(6)-T(1)AM in plasma or brain samples of rats treated with (13)C(6)-T(4). Surprisingly, our method did not detect any endogenous T(1)AM or T(0)AM in plasma from vehicle-treated rats, nor in human plasma or thyroid tissue. Although we are cautious to draw general conclusions from these negative findings and in spite of the fact that insufficient sensitivity of the method related to extractability and stability of T(0)AM cannot be completely excluded at this point, our findings raise questions on the biosynthetic pathways and concentrations of endogenous T(1)AM and T(0)AM.

Prevalence of growth hormone deficiency in Hashimoto's thyroiditis

CONTEXT

Autoimmune hypophysitis can result in GH deficiency (GHD) and is associated with other autoimmune endocrine diseases like Hashimoto's thyroiditis. Recent studies suggest a high prevalence (5%) of GHD in Hashimoto's thyroiditis.

OBJECTIVE

Our objective was to establish the prevalence of GHD in patients with treated autoimmune hypothyroidism (AIH).

PATIENTS

We included patients with spontaneous AIH [thyroid peroxidase antibodies (TPO-Ab) >or=100 kU/liter], who were adequately treated with T(4) (TSH 0.2-5.0 mU/liter). Exclusion criteria were previous I(131) treatment, thyroid surgery, or a history of hypothalamic or pituitary disease. Patients were recruited via our outpatient clinics and via patient self-help organizations.

DESIGN

We measured serum TSH, free T(4), TPO-Ab, and IGF-I. If the IGF-I concentration was below the 10th percentile of age-specific reference values, a GHRH/GH-releasing peptide (GHRP)-6 test was done. GHD was defined as a GH peak after GHRH/GHRP-6 below the 2.5th percentile of age-specific reference values.

MAIN OUTCOME MEASURES

IGF-I concentration and GH peak after GHRH/GHRP-6 test were measured.

RESULTS

From 860 patients who applied, 322 did not satisfy inclusion criteria (157 because TPO-Ab was <100 kU/liter, 165 because TSH was <0.2 or >5.0 mU/liter), and 23 had an exclusion criterion. In the remaining study population of 515 patients (476 female, 39 male), 49 patients (9.5%) had an IGF-I concentration below the 10th percentile. These patients underwent a GHRH/GHRP-6 test. Two patients had a GH peak below the 2.5th percentile.

CONCLUSION

The prevalence of GHD in Dutch patients with AIH is 0.4% (two of 515).

Thyrotropin secretion in mild and severe primary hypothyroidism is distinguished by amplified burst mass and Basal secretion with increased spikiness and approximate entropy

CONTEXT

Twenty-four-hour TSH secretion profiles in primary hypothyroidism have been analyzed with methods no longer in use. The insights afforded by earlier methods are limited.

OBJECTIVE

We studied TSH secretion in patients with primary hypothyroidism (eight patients with severe and eight patients with mild hypothyroidism) with up-to-date analytical tools and compared the results with outcomes in 38 healthy controls.

DESIGN AND METHODS

Patients and controls underwent a 24-h study with 10-min blood sampling. TSH data were analyzed with a newly developed automated deconvolution program, approximate entropy, spikiness assessment, and cosinor regression.

RESULTS

Both basal and pulsatile TSH secretion rates were increased in hypothyroid patients, the latter by increased burst mass with unchanged frequency. Secretory regularity (approximate entropy) was diminished, and spikiness was increased only in patients with severe hypothyroidism. A diurnal TSH rhythm was present in all but two patients, although with an earlier acrophase in severe hypothyroidism. The estimated slow component of the TSH half-life was shortened in all patients.

CONCLUSION

Increased TSH concentrations in hypothyroidism are mediated by amplification of basal secretion and burst size. Secretory abnormalities quantitated by approximate entropy and spikiness were only present in patients with severe disease and thus are possibly related to the increased thyrotrope cell mass.

Thyroid hormone effects on whole-body energy homeostasis and tissue-specific fatty acid uptake in vivo

The effects of thyroid hormone (TH) status on energy metabolism and tissue-specific substrate supply in vivo are incompletely understood. To study the effects of TH status on energy metabolism and tissue-specific fatty acid (FA) fluxes, we used metabolic cages as well as (14)C-labeled FA and (3)H-labeled triglyceride (TG) infusion in rats treated with methimazole and either 0 (hypothyroidism), 1.5 (euthyroidism), or 16.0 (thyrotoxicosis) microg per 100 g/d T(4) for 11 d. Thyrotoxicosis increased total energy expenditure by 38% (P = 0.02), resting energy expenditure by 61% (P = 0.002), and food intake by 18% (P = 0.004). Hypothyroidism tended to decrease total energy expenditure (10%; P = 0.064) and resting energy expenditure (12%; P = 0.025) but did not affect food intake. TH status did not affect spontaneous physical activity. Thyrotoxicosis increased fat oxidation (P = 0.006), whereas hypothyroidism decreased glucose oxidation (P = 0.035). Plasma FA concentration was increased in thyrotoxic but not hypothyroid rats. Thyrotoxicosis increased albumin-bound FA uptake in muscle and white adipose tissue (WAT), whereas hypothyroidism had no effect in any tissue studied, suggesting mass-driven albumin-bound FA uptake. During thyrotoxicosis, TG-derived FA uptake was increased in muscle and heart, unaffected in WAT, and decreased in brown adipose tissue. Conversely, during hypothyroidism TG-derived FA uptake was increased in WAT in association with increased lipoprotein lipase activity but unaffected in oxidative tissues and decreased in liver. In conclusion, TH status determines energy expenditure independently of spontaneous physical activity. The changes in whole-body lipid metabolism are accompanied by tissue-specific changes in TG-derived FA uptake in accordance with hyper- and hypometabolic states induced by thyrotoxicosis and hypothyroidism, respectively.

A rosiglitazone-induced increase in adiponectin does not improve glucose metabolism in HIV-infected patients with overt lipoatrophy

HIV-infected patients on antiretroviral therapy frequently develop changes in body fat distribution and disturbances in glucose metabolism, associated with reduced adiponectin levels. Because adiponectin, principally the high-molecular-weight (HMW) form, has insulin-sensitizing properties, we investigated the effects of an increase in adiponectin on glucose metabolism in HIV-lipodystrophy. In this randomized, double-blind, placebo-controlled trial, we included HIV-1-infected patients with severe lipoatrophy, with an undetectable viral load and who had received neither protease inhibitors nor stavudine for ≥6 mo. Patients were randomized to rosiglitazone [8 mg daily (n = 8)] to increase adiponectin levels or placebo (n = 5) for 16 wk. Peripheral glucose disposal, glucose production, and lipolysis were measured after an overnight fast and during a hyperinsulinemic-euglycemic clamp using stable isotopes. Body composition was assessed by computed tomography and dual-energy X-ray absorptiometry. Although body fat distribution was unaffected, rosiglitazone increased total plasma adiponectin levels by 107% (P < 0.02) and the ratio of HMW to total adiponectin by 73% (P < 0.001). In the placebo group, neither total adiponectin levels (P = 0.62) nor the ratio of HMW to total adiponectin changed (P = 0.94). The marked increase in adiponectin induced by rosiglitazone was not associated with significant changes in basal endogenous glucose production (P = 0.90), basal lipolysis (P = 0.90), insulin-mediated suppression of glucose production (P = 0.17) and lipolysis (P = 0.54) nor with changes in peripheral glucose disposal (P = 0.13). Acknowledging the limited statistical power of our small study, these findings, if confirmed by larger studies, could question the importance of adiponectin in regulating glucose metabolism in HIV-lipodystrophy.

Thyrotropin secretion profiles are not different in men and women

CONTEXT

The hypothalamo-pituitary-thyroid axis in women may differ from that in men. Previous reports have shown an almost 2-fold increased response to TRH in females compared with males.

OBJECTIVE

We analyzed TSH profiles in healthy men and women to delineate differences in the hypothalamo-pituitary-thyroid system.

SUBJECTS AND INTERVENTION

The subjects, 24 men (mean age 44 +/- 3 yr) and 22 women (mean age 42 +/- 3 yr) underwent a 24-h study with blood sampling intervals of 10 min. Premenopausal women were investigated in the early follicular phase of the cycle.

METHODS

Serum TSH concentration profiles were analyzed with a newly developed automated deconvolution program, approximate entropy, and cosinor regression.

RESULTS

Basal and pulsatile TSH secretion, and also pulse frequency, hormone half-lives, and secretory mode were indistinguishable in the two genders. There were no differences in diurnal variation, and the times of maximal secretion coincided. Approximate entropy, reflecting secretory regularity, was not different between men and women. In women but not men, TSH secretion was dependent linearly on age.

CONCLUSIONS

TSH secretion is gender invariant and depends on age in women only.

Variation in phenotypic appearance of Graves' disease: effect of genetic anticipation and duration of complaints

OBJECTIVE

Both genetic and environmental factors contribute to susceptibility of Graves' disease. In this study, we evaluated whether the duration of symptoms or a positive family history of autoimmune thyroid disease (AITD) are related to specific phenotypes in patients with a first episode of Graves' hyperthyroidism (GH).

DESIGN

Cross-sectional multicentre observational study.

PATIENTS

Two hundred and sixty-three consecutive untreated patients (mean age (+/-s.d.) 42.6+/-12.4 years; range 16-79 years) with a first episode of GH were included. Biochemical and clinical severity of GH was evaluated. Participants were asked to complete questionnaires about environmental factors (smoking behavior, use of estrogens, stress etc.), the duration of symptoms (interval between start of symptoms and date of referral) and family history for AITD. We ascertained the autoimmune nature of thyroid disease in affected relatives. Family history scores (FHS; high score indicating a close genetic relationship and/or a large number of affected relatives) were calculated for patients with a positive family history for AITD.

RESULTS

The peak incidence for the diagnosis of GH was 2-3 months after onset of symptoms (32% of patients). Duration of symptoms was negatively associated with age (P for trend=0.04). A positive family history for AITD was present in 42.6% of patients. Patients with the highest FHS were more often male (P=0.01) while age at onset was lower (P=0.02) compared to patients with a lower FHS. Among patient groups with different FHS, no differences were found in exposure to environmental factors, nor in clinical or biochemical severity of hyperthyroidism.

CONCLUSION

Our study does not support the hypothesis that a short duration of thyrotoxic symptoms until diagnosis is related to more severe hyperthyroidism in Graves' disease. We have found supporting evidence for the existence of genetic anticipation in Graves' disease by means of a lower age of onset in the group with the highest FHS.

Evaluation of endocrine tests. D: the prolonged fasting test for insulinoma

OBJECTIVE

To establish the diagnostic performance of the prolonged fasting test in patients suspected of insulinoma.

METHODS

We included all patients who were referred to our department between August 1995 and August 2006 with a clinical suspicion of insulinoma. Insulinoma was diagnosed by a positive Whipple's triad during the prolonged fast in combination with an insulin/C-peptide ratio below 1. The presence of insulinoma was confirmed by histopathological data, which was considered the golden standard. If the prolonged fast was negative, long-term follow-up was obtained.

RESULTS

Ten patients had a positive Whipple's triad during the prolonged fast: eight had a histologically proven insulinoma, and two had factitious hypoglycaemia (insulin/C-peptide ratio >1.0) One additional patient likely had an insulinoma, but the Whipple's triad remained absent at up to 56 hours of fasting. Follow-up (median 53 months (3 to 142) in 76% of patients with a negative fasting test revealed no missed cases of insulinoma. During the prolonged fast the glucose, insulin and C-peptide concentrations overlapped in patients with and without insulinoma.

CONCLUSION

In our centre, the prolonged fasting test defined as a positive Whipple's triad in combination with an insulin/C-peptide ratio <1 had a sensitivity of 88.9% and a specificity of 100% for the diagnosis of insulinoma.

Biochemical and circulatory parameters during purely mental stress

In order to evaluate biochemical and circulatory parameters during purely mental stress, 20 healthy medical students were studied before, during and at the end of an important written medical examination. Plasma catecholamines and diastolic blood pressure rose significantly during the examination, whereas systolic blood pressure did not change and heart rate declined. Continuous ECG recording in 12 of the subjects showed a high peak in heart rate at the start of the examination, quickly followed by a rapid decline to values seen on the previous day. It is suggested that in mental stress without physical effort, the enhanced sympathetic activity triggers an increase in parasympathetic activity which overrides the circulatory effects of the former.

Is the coronary care unit a coronary scare unit?

In order to evaluate the influence of stress associated with admission to a coronary care unit (CCU), we measured the plasma noradrenaline and adrenaline concentrations during the first CCU hour in 47 patients with suspected acute myocardial infarction (AMI). These values were compared with those in healthy hospital personnel. AMI patients had significantly higher plasma catecholamines than patients with no apparent cardiac disease. The highest values were found in patients with complicated AMI. Although the patients had significantly higher plasma catecholamines than hospital personnel, it is concluded that the circulation rather than the situation determines plasma noradrenaline and adrenaline levels and that stress does not play a major role. This study provides no support for the suggestion that home care is preferable for patients with AMI as a means of avoiding the stress of admission to hospital.

Establishment of reference values for endocrine tests. Part VII: growth hormone deficiency

BACKGROUND

Plasma insulin-like growth factor (IGF-I) concentration can be used as a rough indicator of the growth-hormone status. However, for the diagnosis of growth hormone deficiency, dynamic tests are required. The growth hormone (GH) response in the insulin tolerance test (ITT) is considered to be the gold standard in this respect. An alternative for the ITT is the GHRH/ GHRP-6 test, which has fewer side effects. In this study we established reference values for IGF-I levels and for the GH response in both dynamic tests.

METHODS

We studied 296 subjects recruited from the general population, equally distributed according to sex and aged between 20 and 70 years. Serum IGF-I level was measured in all subjects and an insulin tolerance test (0.15 U/kg Actrapid iv) and GHRH/GHRP-6 test (1 microg GHRH/kg and 1 microg GHRP-6/kg) were performed in 49 subjects.

RESULTS

In multivariate analyses both IGF-I and the GH response in the ITT were significantly influenced by age, whereas the GH response in the GHRH/GHRP-6 test was significantly affected by BMI. There was no sex difference in IGF-I and in the GHRH/GHRP-6 test, but in the ITT males had a higher GH peak. There was a significant correlation between the GH responses in both tests, and the GH response was significantly higher in the GHRH/GHRP-6 test than in the ITT. Age-adjusted reference values were established for each test.

CONCLUSION

We have established age-adjusted reference values for serum IGF-I and for the GH response in the ITT and GHRH/GHRP-6 test.

Evaluation of Endocrine Tests. C: glucagon and clonidine test in phaeochromocytoma

BACKGROUND

The diagnosis of phaeochromocytoma is based on the demonstration of catecholamine excess. Urine and plasma metanephrine measurements are highly sensitive tests for the diagnosis of phaeochromocytoma, but moderate elevations in metanephrines lack optimal specificity. In this study we aimed to evaluate the diagnostic value of additional tests, i.e. glucagon stimulation and clonidine suppression test, in patients with moderately elevated catecholamines and/or metanephrines.

METHODS

Patients with suspected phaeochromocytoma with moderately elevated catecholamines and/or metanephrines in plasma or urine were subjected to the glucagon stimulation and clonidine suppression test. The presence of phaeochromocytoma was confirmed by histology and the absence by a disease-free extended follow-up.

RESULTS

Fifty-five patients were included. Phaeochromocytoma was diagnosed in 11 patients. The follow-up period in patients without phaeochromocytoma was 56 (19 to 154) months. The sensitivity of the glucagon test was 30% and the specificity 100%. The clonidine test had no discriminative power, because the area under the ROC curve was not significantly different from 0.5.

CONCLUSION

The clonidine suppression test without normetanephrine measurements and the glucagon stimulation test are not sensitive enough to safely exclude phaeochromocytoma in patients with mildly elevated plasma or urine catecholamines.

Early endotoxemia increases peripheral and hepatic insulin sensitivity in healthy humans

CONTEXT

Sepsis-induced hypoglycemia is a well known, but rare, event of unknown origin.

OBJECTIVE

The aim of the study was to obtain insight into the mechanism of sepsis-induced hypoglycemia, focusing on glucose kinetics and insulin sensitivity measured with stable isotopes by using the model of human endotoxemia.

DESIGN

Glucose metabolism was measured during two hyperinsulinemic [insulin levels of 100 pmol/liter (low-dose clamp) and 400 pmol/liter (medium-dose clamp)] euglycemic (5 mmol/liter) clamps on two occasions: without or with lipopolysaccharide (LPS).

SETTING

The study was conducted at the Academic Medical Center, Metabolic and Clinical Research Unit (Amsterdam, The Netherlands).

PARTICIPANTS

Eighteen healthy male volunteers participated in the study.

INTERVENTION

A hyperinsulinemic euglycemic (5 mmol/liter) clamp with LPS (two groups of six subjects; insulin infusion at rates of either 10 or 40 mU.m(-2).min(-1)) or without LPS (n = 6; both insulin infusions in same subjects).

MAIN OUTCOME MEASURE

We measured hepatic and peripheral insulin sensitivity.

RESULTS

Hepatic insulin sensitivity, defined as a decrease in endogenous glucose production during hyperinsulinemia (100 pmol/liter), was higher in the LPS group compared to the control group (P = 0.010). Insulin-stimulated peripheral glucose uptake was higher in both clamps after LPS compared to the control setting (P = 0.006 and 0.010), despite a significant increase in the plasma concentrations of norepinephrine and cytokines in the LPS group during both clamps.

CONCLUSIONS

These data indicate that shortly (2 h) after administration of LPS, peripheral and hepatic insulin sensitivity increase. This may contribute to the hypoglycemia occurring in some patients with critical illness, especially in the setting of intensive insulin therapy.

Age and stress as determinants of the severity of hyperthyroidism caused by Graves' disease in newly diagnosed patients

OBJECTIVE

The evidence that stress may provoke Graves' hyperthyroidism in genetically susceptible subjects is substantial. Whether exposure to stress is related to the severity of thyrotoxicosis has not been studied. Advancing age is associated with not only less severe Graves' hyperthyroidism but also self-reported stress. We tested the hypothesis whether advancing age is associated with less exposure to stress, resulting in a lower immunological response, and less severe Graves' hyperthyroidism.

DESIGN

Cross-sectional multicenter study.

PATIENTS

Two hundred and sixty-three consecutive untreated patients with a first episode of Graves' hyperthyroidism were included. The severity of Graves' hyperthyroidism was evaluated biochemically (freeT(4)-index and freeT(3)-index, thyrotropin-binding inhibitory immunoglobulin (TBII)) and clinically by the hyperthyroid symptom scale score (HSS score). Stress exposure was quantitated by three questionnaires.

RESULTS

Advancing age was associated with less severe Graves' hyperthyroidism, both biochemically by lower serum freeT(3)-index and freeT(4)-index (P<0.01), lower serum TBII (P=0.05), and clinically by lower HSS scores (P=0.04) and smaller goiter size (P<0.01). FreeT(3)-index and freeT(4)-index were directly associated with HSS scores (P<0.01). Stress scores were associated with HSS scores (P<0.01) but not with biochemical severity of Graves' hyperthyroidism. Advancing age was associated with lower scores for stress exposure. Multivariate regression analysis showed that HSS score was independently related to the tendency to report negative feelings (P<0.01) but not to other stress scores and also not to age.

CONCLUSION

Advancing age is associated with less exposure to stress, lower serum TBII and less severe clinical and biochemical Graves' hyperthyroidism. Because no direct relationship exists between stress exposure and TBII or freeT(3)-index and freeT(4)-index, we reject our hypothesis that less stress is causally related to biochemically less severe Graves' hyperthyroidism in old age. HSS score is primarily determined by negative feelings and not by age.