Metabolic syndrome and kidney disease

The clustering of cardiovascular risk factors was noted already a century ago, but it is only recently that a link between the CV risk cluster and insulin resistance has been postulated - a proposal which is not unanimously accepted. There is no doubt, however, that obesity per se impacts on renal function and the risk of chronic kidney disease (CKD). Particularly obesity early in life is an important predictor of CKD in adult life, but in adults as well a high body mass index (BMI) is an independent predictor of ESRD. The BMI threshold is lower in Asians. The link between obesity and CKD is not fully explained by the association between obesity and diabetes or hypertension respectively. Obesity is associated with increased glomerular filtration rate and renal blood flow, glomerulomegaly and in extreme cases focal segmental glomerulosclerosis. The causal role of obesity is underlined by the effect of weight loss on proteinuria and glomerular hyperfiltration. An even better predictor than BMI is visceral obesity (waist circumference). For kidney disease in the metabolic syndrome it is relevant that insulin resistance is linked to salt sensitivity and increased tubular reabsorption of sodium. Recent evidence points to adverse effects of aldosterone on podocytes, mediated by reactive oxygen species and resulting from hypothetical stimulants of aldosterone synthesis by visceral adipocytes.