Metabolic syndrome and renal sodium handling in three ethnic groups living in England

Abstract

Aim/hypothesis. Increased proximal renal sodium reabsorption is associated with central adiposity and insulin resistance in white men. Our study examined whether this association also exists in other ethnic groups with different prevalences of insulin resistance and associated metabolic abnormalities. Methods. We studied the association between fractional renal excretion of endogenous lithium (FELi) and metabolic syndrome in a population study of 1190 randomly selected men and women who where 40 to 59 years of age (426 white, 397 of African and 367 of South Asian origin). Anthropometric values, blood pressure, biochemical values, questionnaire data and timed urine collections were obtained with standardised techniques. Endogenous lithium in serum and urine was measured by absorption spectrophotometry. Metabolic markers were the homeostasis model assessment (HOMA) index, waist circumference, serum triglycerides, serum HDL cholesterol and metabolic syndrome as defined by Adult Treatment Panel III criteria.Results. In white men and women a higher rate of proximal sodium re-absorption was inversely associated with higher waist circumference, serum triglycerides and HOMA index, and with lower serum HDL cholesterol (all p≤0.001)

Abnormalities of renal sodium handling in the metabolic syndrome. Results of the Olivetti Heart Study

“…Thus, our findings suggest that in subjects with MS a greater avidity of the renal proximal tubule for sodium is compensated for by relative hyperfiltration, which is sustained, at least in part, by higher systemic blood pressure. These findings are in accordance with the results of a recent study on a sample of a Caucasian population in England [7]. They are also in keeping with previous demonstrations of an altered modulation of FPRNa in relation to salt sensitivity in both normotensive [4] and hypertensive individuals [5].…”

Enhanced sodium sensitivity and disturbed circadian rhythm of blood pressure in essential hypertension

“…These findings indicate that essential hypertensive patients with metabolic syndrome, whose sodium sensitivity of blood pressure was elevated, were likely to manifest as non-dippers under a high-sodium diet, and their nocturnal blood pressure fall was restored by sodium restriction. On the other hand, in white men and women, the fractional excretion rates of lithium were inversely associated with a higher waist circumstance and the HOMA index [22], but no associations were found in people of either African or South Asian origin. These results indicated differences in the association between metabolic syndrome and salt sensitivity of the blood pressure.…”

Thiazolidinediones and the renal and hormonal response to water immersion-induced volume expansion in type 2 diabetes mellitus

“…We also decided to study wellcontrolled type 2 diabetes subjects who were, as far as we could judge, clinically free from complications or any comorbidity or treatment. Studies have shown that abnormalities of tubular sodium handling occur even in subjects with the metabolic syndrome (2) and certainly in uncomplicated type 2 diabetes (30). Subjects were studied under fasting conditions with blood glucose levels below the renal threshold to avoid the need for insulin clamping, which would have introduced further variables.…”