Marked association between obesity and glomerular hyperfiltration: a cross-sectional study in an African population.
BACKGROUND
Obesity and African American ethnicity are established independent risk factors for the development of chronic kidney disease. No data exist about the association between obesity and renal hemodynamics in the African region.


METHODS
Cross-sectional study.


METHODS
301 nondiabetic participants (97 lean, 108 overweight, and 96 obese) of African descent with a positive family history of hypertension from the Seychelles islands.


METHODS
Body mass index (BMI).


RESULTS
Glomerular hyperfiltration, glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and filtration fraction.


METHODS
GFR and ERPF were measured using inulin and para-aminohippurate clearances, respectively. Participants' baseline demographics, laboratory data, and blood pressure were measured using standard techniques.


RESULTS
The prevalence of glomerular hyperfiltration (defined as GFR >or=140 mL/min) increased across BMI categories (7.2%, 14.8%, and 27.1% for lean, overweight, and obese participants, respectively; P < 0.001). Higher BMI was associated with higher median GFR (99, 110, and 117 mL/min for lean, overweight, and obese participants, respectively; P < 0.001), ERPF (424, 462, and 477 mL/min, respectively; P = 0.01), and filtration fraction (0.23, 0.24, and 0.25; P < 0.001). Multivariate analyses adjusting for age, sex, blood pressure, fasting glucose level, and urinary sodium excretion and accounting for familial correlations confirmed the associations between high BMI (>25 kg/m(2)) and increased GFR, ERPF, and filtration fraction. No association between BMI categories and GFR was found with adjustment for body surface area.


CONCLUSIONS
Participants had a positive family history of hypertension.


CONCLUSIONS
Overweight and obesity are associated with increased GFR, ERPF, and filtration fraction and a high prevalence of glomerular hyperfiltration in nondiabetic individuals of African descent. The absence of associations between BMI categories and GFR indexed for body surface area raises questions regarding the appropriateness of indexing GFR for body surface area in overweight populations.
Department of Medicine, Service of Nephrology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
Grégoire
G
Wuerzner
Menno
M
Pruijm
Marc
M
Maillard
Pascal
P
Bovet
Claude
C
Renaud
Michel
M
Burnier
Murielle
M
Bochud
D000328:Adult; D015992:Body Mass Index; D003430:Cross-Sectional Studies; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006439:Hemodynamics; D006801:Humans; D007668:Kidney / Q000098:blood supply; D007678:Kidney Glomerulus / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009765:Obesity / Q000208:ethnology* / Q000503:physiopathology*; D050177:Overweight / Q000208:ethnology / Q000503:physiopathology; D012039:Regional Blood Flow; D012750:Seychelles / Q000453:epidemiology