Visceral Fat Is Linked to Inflammation in Dialysis Patients, While Subcutaneous Fat Marks Nutritional Status

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In dialysis patients, visceral fat is a marker of inflammation while subcutaneous fat is a marker of nutritional status, suggests a study in American Journal of Kidney Diseases.

The cross-sectional study included 609 adult hemodialysis patients enrolled in the US Renal Data System’s ACTIVE/ADIPOSE study. Participants underwent several measurements: body mass index (BMI), waist circumference as an indicator of visceral fat, and percentage body fat as an indicator of subcutaneous fat. The two fat measures were evaluated for association with markers of inflammation, nutrition, and adiposity-related hormones.

Body mass index was directly related to the inflammatory markers C-reactive protein and interleukin-6 (IL-6), but not with markers of nutrition, i.e., prealbumin or albumin. BMI was inversely associated with adiponectin and directly related to leptin. In a model including proxies for both visceral and subcutaneous fat, percentage body fat—the indicator for subcutaneous fat—was unrelated to C-reactive protein, but was inversely associated with IL-6.

Also in this model, waist circumference was associated with markers of inflammation but was inversely associated with prealbumin and albumin. Percentage body fat was directly related to these nutritional markers. Waist circumference was indirectly related to adiponectin and indirectly related to leptin.

Dialysis patients with BMI higher than the normal range generally have a higher survival rate, a phenomenon called the “obesity paradox,” which has confounded researchers and practitioners. Yet BMI is a general marker of adiposity, and does not distinguish between subcutaneous and visceral fat, which may have differing metabolic and inflammatory characteristics. Determining the type of fat—visceral or subcutaneous—may help unravel the obesity paradox, but longitudinal studies are needed to clarify the associations between measures of body fat and markers of inflammation.

Added to previous findings, the results of this cohort study of dialysis patients suggest that “higher subcutaneous fat may account for the observed survival advantage associated with higher BMI.”

References

1. Delgado C, et al. Associations of body mass index and body fat with markers of inflammation and nutrition among patients receiving hemodialysis. Am J Kidney Dis 2017; DOI: [http://dx.doi.org/10.1053/j.ajkd.2017.06.028].

October/November 2017 (Vol. 9, Number 10 & 11)