Norman N. Chan

Drug-induced endocrine and metabolic disorders

Complex interactions exist amongst the various components of the neuroendocrine system in order to maintain homeostasis, energy balance and reproductive function. These components include the hypothalamus-pituitary-adrenal and -gonadal axes, the renin-angiotensin-aldosterone system, the sympathetic nervous system and the pancreatic islets. These hormones, peptides and neurotransmitters act in concert to regulate the functions of many organs, notably the liver, muscles, kidneys, thyroid, bone, adrenal glands, adipocytes, vasculature, intestinal tract and gonads, through many intermediary pathways. Endocrine and metabolic disorders can arise from imbalance amongst numerous hormonal factors. These disturbances may be due to endogenous processes, such as increased secretion of hormones from a tumour, as well as exogenous drug administration. Drugs can cause endocrine abnormalities via different mechanisms, including direct alteration of hormone production, changes in the regulation of the hormonal axis, effects on hormonal transport, binding, and signalling, as well as similar changes to counter-regulatory hormone systems. Furthermore, drugs can affect the evaluation of endocrine parameters by causing interference with diagnostic tests. Common drug-induced endocrine and metabolic disorders include disorders of carbohydrate metabolism, electrolyte and calcium abnormalities, as well as drug-induced thyroid and gonadal disorders. An understanding of the proposed mechanisms of these drug effects and their evaluation and differential diagnosis may allow for more critical interpretation of the clinical observations associated with such disorders, better prediction of drug-induced adverse effects and better choices of and rationales for treatment.

Prediction of cardiovascular and total mortality in Chinese type 2 diabetic patients by the WHO definition for the metabolic syndrome

Aim:  The aim of this study is to investigate the prevalence of metabolic syndrome (MES) in type 2 diabetic patients and the predictive values of the World Health Organization (WHO) and National Cholesterol Education Programme (NCEP) definitions and the individual components of the MES on total and cardiovascular mortality.

Effects of gender, Helicobacter pylori and hepatitis B virus serology status on cardiovascular and renal complications in Chinese type 2 diabetic patients with overt nephropathy.

Background:  The aim of this study was to investigate whether chronic infections with Helicobacter pylori and hepatitis B virus (HBV) might affect clinical outcomes in Chinese type 2 diabetic patients with advanced nephropathy.

Reduction of Total Homocysteine Levels by Oral Folic Acid Fails to Improve Endothelial Function in Children With Chronic Renal Failure

To the Editor: We read with great interest the study by Bennett-Richards and colleagues1 that examined the effect of oral folic acid on total homocysteine concentrations and endothelial function in children with chronic renal failure (CRF). They found that folic acid supplementation for 8 weeks significantly reduced homocysteine concentrations and increased low-density lipoprotein lag times (indicating a reduction in susceptibility of low-density lipoprotein to oxidation). Despite these favorable effects of folic acid on parameters that are detrimental to endothelial function, however, there was no significant improvement in flow-mediated dilatation (FMD) compared with placebo.1 The authors suggested several explanations, including the inability to normalize homocysteine levels in …