Management of incidental adrenal tumours.

An incidental adrenal tumour, described in this article as an “adrenal incidentaloma,” is an adrenal mass discovered during imaging that was not performed for suspected adrenal disease. These are being detected more frequently in an ageing population through the increased use of computed tomography (eg, computed tomography urogram, or colonoscopy) and magnetic resonance imaging (MRI) scans with enhanced resolution. This article highlights the management of adrenal incidentalomas, collating recommendations from international guidelines, and is aimed at non-specialists

Salivary androgens in adolescence and their value as a marker of puberty: results from the SCAMP cohort

Context: Salivary androgens represent non-invasive biomarkers of puberty that may have utility in clinical and population studies. Objective: To understand normal age-related variation in salivary sex steroids and demonstrate their correlation to pubertal development in young adolescents. Design, Setting, and participants: School-based cohort study of 1,495 adolescents at two time points for collecting saliva samples approximately two years apart. Outcome measures: The saliva samples were analyzed for five androgens (testosterone, androstenedione (A4), 17-hydroxyprogesterone (17-OHP), 11-ketotestosterone (11-KT) and 11β-hydroxyandrostenedione (11-OHA4)) using LC-MS/MS; in addition, salivary dehydroepiandrosterone (DHEA) and oestradiol (OE2) were analyzed by ELISA. Pubertal staging was self-reported using the pubertal development scale (PDS). Results: In 1,236 saliva samples from 903 boys aged between 11-16 years, salivary androgens except DHEA exhibited an increasing trend with an advancing age (ANOVA, p<0.001), with salivary testosterone and A4 concentration showing the strongest correlation (r=0.55, p<0.001 and r=0.48, p<0.001, respectively). In a subgroup analysis of 155 and 63 saliva samples in boys and girls, respectively morning salivary testosterone concentrations showed the highest correlation with composite PDS scores and voice-breaking category from PDS self-report in boys (r=0.75, r=0.67, respectively). In girls, salivary DHEA and OE2 had negligible correlations with age or composite PDS scores. Conclusion: In boys aged 11-16 years, increase in salivary testosterone and A4 is associated with self-reported pubertal progress and represent valid non-invasive biomarkers of puberty in boys

Glucocorticoids regulate AKR1D1 activity in human liver in vitro and in vivo

Steroid 5β-reductase (AKR1D1) is highly expressed in human liver where it inactivates endogenous glucocorticoids and catalyses an important step in bile acid synthesis. Endogenous and synthetic glucocorticoids are potent regulators of metabolic phenotype and play a crucial role in hepatic glucose metabolism. However, the potential of synthetic glucocorticoids to be metabolised by AKR1D1 as well as to regulate its expression and activity has not been investigated. The impact of glucocorticoids on AKR1D1 activity was assessed in human liver HepG2 and Huh7 cells; AKR1D1 expression was assessed by qPCR and Western blotting. Genetic manipulation of AKR1D1 expression was conducted in HepG2 and Huh7 cells and metabolic assessments were made using qPCR. Urinary steroid metabolite profiling in healthy volunteers was performed pre- and post-dexamethasone treatment, using gas chromatography-mass spectrometry. AKR1D1 metabolised endogenous cortisol, but cleared prednisolone and dexamethasone less efficiently. In vitro and in vivo, dexamethasone decreased AKR1D1 expression and activity, further limiting glucocorticoid clearance and augmenting action. Dexamethasone enhanced gluconeogenic and glycogen synthesis gene expression in liver cell models and these changes were mirrored by genetic knockdown of AKR1D1 expression. The effects of AKR1D1 knockdown were mediated through multiple nuclear hormone receptors, including the glucocorticoid, pregnane X and farnesoid X receptors. Glucocorticoids down-regulate AKR1D1 expression and activity and thereby reduce glucocorticoid clearance. In addition, AKR1D1 down-regulation alters the activation of multiple nuclear hormone receptors to drive changes in gluconeogenic and glycogen synthesis gene expression profiles, which may exacerbate the adverse impact of exogenous glucocorticoids

The contribution of serum cortisone and glucocorticoid metabolites to detrimental bone health in patients receiving hydrocortisone therapy

Background Glucocorticoid therapy is the most common cause of iatrogenic osteoporosis. Less is known regarding the effect of glucocorticoids when used as replacement therapy on bone remodelling in patients with adrenal insufficiency. Enhanced intracellular conversion of inactive cortisone to active cortisol, by 11 beta-hydroxysteroid dehydrogenase type 1(11β-HSD1) and other enzymes leading to alterations in glucocorticoid metabolism, may contribute to a deleterious effect on bone health in this patient group. Methods Study design: An open crossover prospective study randomizing ten hypopituitary men, with severe ACTH deficiency, to three commonly used hydrocortisone dose regimens. Measurements: Following 6 weeks of each regimen, patients underwent 24-h serum cortisol/cortisone sampling, measurement of bone turnover markers, and a 24-h urine collection for measurement of urinary steroid metabolites by gas chromatography-mass spectrometry (GC-MS). Serum cortisone and cortisol were analysed by liquid chromatography-mass spectrometry (LC-MS). Results Dose-related and circadian variations in serum cortisone were seen to parallel those for cortisol, indicating conversion of ingested hydrocortisone to cortisone. The median area under the curve (AUC) of serum cortisone was significantly higher in patients on dose A (20 mg/10 mg) [670.5 (IQR 621–809.2)] compared to those on dose C (10 mg/5 mg) [562.8 (IQR 520.1–619.6), p = 0.01]. A negative correlation was observed between serum cortisone and bone formation markers, OC [1–49] (r = − 0.42, p = 0.03), and PINP (r = − 0.49, p = 0.01). There was a negative correlation between the AUC of night-time serum cortisone levels with the bone formation marker, OC [1–49] (r = − 0.41, p = 0.03) but there were no significant correlations between day-time serum cortisone or cortisol with bone turnover markers. There was a negative correlation between total urinary cortisol metabolites and the bone formation markers, PINP (r = − 0.39, p = 0.04), and OC [1–49] (r = − 0.35, p = 0.06). Conclusion Serum cortisol and cortisone and total urinary corticosteroid metabolites are negatively associated with bone turnover markers in patients receiving replacement doses of hydrocortisone, with nocturnal glucocorticoid exposure having a potentially greater influence on bone turnover. Trial registration Irish Medicines Board Clinical Trial Number – CT900/459/1 and EudraCT Number – 2007-005018-37. Registration date: 07-09-2007

Investigating the complex genetic architecture of ankle-brachial index, a measure of peripheral arterial disease, in non-Hispanic whites

<p>Abstract</p> <p>Background</p> <p>Atherosclerotic peripheral arterial disease (PAD) affects 8–10 million people in the United States and is associated with a marked impairment in quality of life and an increased risk of cardiovascular events. Noninvasive assessment of PAD is performed by measuring the ankle-brachial index (ABI). Complex traits, such as ABI, are influenced by a large array of genetic and environmental factors and their interactions. We attempted to characterize the genetic architecture of ABI by examining the main and interactive effects of individual single nucleotide polymorphisms (SNPs) and conventional risk factors.</p> <p>Methods</p> <p>We applied linear regression analysis to investigate the association of 435 SNPs in 112 positional and biological candidate genes with ABI and related physiological and biochemical traits in 1046 non-Hispanic white, hypertensive participants from the Genetic Epidemiology Network of Arteriopathy (GENOA) study. The main effects of each SNP, as well as SNP-covariate and SNP-SNP interactions, were assessed to investigate how they contribute to the inter-individual variation in ABI. Multivariable linear regression models were then used to assess the joint contributions of the top SNP associations and interactions to ABI after adjustment for covariates. We reduced the chance of false positives by 1) correcting for multiple testing using the false discovery rate, 2) internal replication, and 3) four-fold cross-validation.</p> <p>Results</p> <p>When the results from these three procedures were combined, only two SNP main effects in <it>NOS3</it>, three SNP-covariate interactions (<it>ADRB2 </it>Gly 16 – lipoprotein(a) and <it>SLC4A5 </it>– diabetes interactions), and 25 SNP-SNP interactions (involving SNPs from 29 different genes) were significant, replicated, and cross-validated. Combining the top SNPs, risk factors, and their interactions into a model explained nearly 18% of variation in ABI in the sample. SNPs in six genes (<it>ADD2, ATP6V1B1, PRKAR2B, SLC17A2, SLC22A3, and TGFB3</it>) were also influencing triglycerides, C-reactive protein, homocysteine, and lipoprotein(a) levels.</p> <p>Conclusion</p> <p>We found that candidate gene SNP main effects, SNP-covariate and SNP-SNP interactions contribute to the inter-individual variation in ABI, a marker of PAD. Our findings underscore the importance of conducting systematic investigations that consider context-dependent frameworks for developing a deeper understanding of the multidimensional genetic and environmental factors that contribute to complex diseases.</p

Complexity in the genetic architecture of leukoaraiosis in hypertensive sibships from the GENOA Study

<p>Abstract</p> <p>Background</p> <p>Subcortical white matter hyperintensity on magnetic resonance imaging (MRI) of the brain, referred to as leukoaraiosis, is associated with increased risk of stroke and dementia. Hypertension may contribute to leukoaraiosis by accelerating the process of arteriosclerosis involving penetrating small arteries and arterioles in the brain. Leukoaraiosis volume is highly heritable but shows significant inter-individual variability that is not predicted well by any clinical covariates (except for age) or by single SNPs.</p> <p>Methods</p> <p>As part of the Genetics of Microangiopathic Brain Injury (GMBI) Study, 777 individuals (74% hypertensive) underwent brain MRI and were genotyped for 1649 SNPs from genes known or hypothesized to be involved in arteriosclerosis and related pathways. We examined SNP main effects, epistatic (gene-gene) interactions, and context-dependent (gene-environment) interactions between these SNPs and covariates (including conventional and novel risk factors for arteriosclerosis) for association with leukoaraiosis volume. Three methods were used to reduce the chance of false positive associations: 1) false discovery rate (FDR) adjustment for multiple testing, 2) an internal replication design, and 3) a ten-iteration four-fold cross-validation scheme.</p> <p>Results</p> <p>Four SNP main effects (in <it>F3</it>, <it>KITLG</it>, <it>CAPN10</it>, and <it>MMP2</it>), 12 SNP-covariate interactions (including interactions between <it>KITLG </it>and homocysteine, and between <it>TGFB3 </it>and both physical activity and C-reactive protein), and 173 SNP-SNP interactions were significant, replicated, and cross-validated. While a model containing the top single SNPs with main effects predicted only 3.72% of variation in leukoaraiosis in independent test samples, a multiple variable model that included the four most highly predictive SNP-SNP and SNP-covariate interactions predicted 11.83%.</p> <p>Conclusion</p> <p>These results indicate that the genetic architecture of leukoaraiosis is complex, yet predictive, when the contributions of SNP main effects are considered in combination with effects of SNP interactions with other genes and covariates.</p

Cystatin C: current position and future prospects.

Abstract Cystatin C is a low-molecular-weight protein which has been proposed as a marker of renal function that could replace creatinine. Indeed, the concentration of cystatin C is mainly determined by glomerular filtration and is particularly of interest in clinical settings where the relationship between creatinine production and muscle mass impairs the clinical performance of creatinine. Since the last decade, numerous studies have evaluated its potential use in measuring renal function in various populations. More recently, other potential developments for its clinical use have emerged. This review summarises current knowledge about the physiology of cystatin C and about its use as a renal marker, either alone or in equations developed to estimate the glomerular filtration rate. This paper also reviews recent data about the other applications of cystatin C, particularly in cardiology, oncology and clinical pharmacology. Clin Chem Lab Med 2008;46:1664-86