Lower hemoglobin concentrations and subsequent decline in kidney function in an apparently healthy population aged 60 year and older

BackgroundAnemia and decreased kidney function are recognized as risk factors for morbidity and mortality in the elderly. The role of hemoglobin in renal function changes among elderly patients is not fully understood.MethodsOf 1500 people screened, 121 normotensive non-diabetic elderly patients were recruited, and underwent biochemistry examinations at the baseline, second and fourth years of a 4-year longitudinal study. Serum creatinine and calculated renal parameters, including the Cockroft–Gault (CG) formula, Modification of Diet in Renal Disease (MDRD) Study and abbreviated MDRD (abMDRD) equations were used to evaluate renal function and progression of kidney disease. Chronic kidney disease (CKD) was defined as a glomerular filtration rate (GFR) of < 60 ml/min/1.73 m2. Multivariate regression analyses were used to explore predictors for decline in renal parameters.ResultsAges ranged from 60 to 81 year (mean: 71.8 ± 3.8). Baseline hemoglobin concentrations ranged from 11.9 to 17.3 g/dl (mean: 14.1 ± 1.1). Serum creatinine increased and CG creatinine clearance (CrCl), MDRD and abMDRD GFR decreased during follow-up (all p ≤ 0.001). The prevalence of CKD significantly increased only in those with baseline hemoglobin concentrations of < 14 g/dl (p ≤ 0.03, based on findings of both MDRD and abMDRD GFR). Baseline hemoglobin correlates with 4-year changes of MDRD and abMDRD GFR in univariate (both p < 0.001) and multivariate regression analyses (both p < 0.05).ConclusionsThis longitudinal study revealed that the aging process was associated with decline of renal function in the elderly. Because hemoglobin concentrations are an independent predictor for subsequent decline in kidney function, it should be considered in the assessment of renal disease and GFR in the elderly.