Fatty kidney, hypertension, and chronic kidney disease: the Framingham Heart Study

Abstract

Ectopic fat depots may mediate local and systemic disease. Animal models of diet-induced obesity demonstrate increased fat accumulation in the renal sinus. The association of renal sinus fat with hypertension, chronic kidney disease, and other metabolic disorders has not been studied in a large, community-based sample. Participants from the Framingham Heart Study (n=2923; mean age: 54 years; 51% women) underwent quantification of renal sinus fat area using computed tomography. High renal sinus fat ("fatty kidney") was defined using sex-specific 90th percentiles in a healthy referent subsample. Multivariable linear and logistic regression was used to model metabolic risk factors as a function of fatty kidney and log-transformed renal sinus fat. Multivariable models were adjusted for age, sex, and outcome-specific covariates and then additionally adjusted for body mass index or abdominal visceral adipose tissue. The prevalence of fatty kidney was 30.1% (n=879). Individuals with fatty kidney had a higher odds ratio (OR) of hypertension (OR: 2.12; P<0.0001), which persisted after adjustment for body mass index (OR: 1.49; P<0.0001) or visceral adipose tissue (OR: 1.24; P=0.049). Fatty kidney was also associated with an increased OR for chronic kidney disease (OR: 2.30; P=0.005), even after additionally adjusting for body mass index (OR: 1.86; P=0.04) or visceral adipose tissue (OR: 1.86; P=0.05). We observed no association between fatty kidney and diabetes mellitus after adjusting for visceral adipose tissue. In conclusion, fatty kidney is a common condition that is associated with an increased risk of hypertension and chronic kidney disease. Renal sinus fat may play a role in blood pressure regulation and chronic kidney disease.

Figure 1. Prevalence of Chronic Kidney Disease (CKD) by Fatty Kidney and Abdominal Visceral Adipose Tissue (VAT) Distribution Patterns

CKD_cys is defined as eGFR<60 mL/min/1.73m², based on the Cystatin-C only CKD-EPI equation. CKD_crea is defined as eGFR<60 mL/min/1.73m², based on the modified MDRD Study Equation. Not fatty kidney and normal VAT (Group 1); Fatty kidney and Normal VAT (Group 2); Not fatty kidney and high VAT (Group 3); ■ Fatty kidney and high VAT (Group 4). For comparison, CKD_cys and CKD_crea status at the 7^th Offspring exam cycle are presented. P-values are adjusted for age and sex. CKD_crea available in 2943 participants (Group 1 N=1437; Group 2 N=236; Group 3 N=605; Group 4 N=665). CKD_cys available in 1206 participants with cystatin-C measures (Group 1 N=375; Group 2 N=122; Group 3 N=273; Group 4 N=436).