Renal function in the oldest-old on an acute geriatric ward

Evaluation of renal function and relation to risk factors for renal failure in very old patients admitted to an acute geriatric ward.

Retrospective chart review of patients aged 80 years and over, admitted to the acute geriatric ward from August 1998 till August 1999. Recorded data were: age, gender, previous medical history, primary diagnosis, medication use, weight, serum creatinine, BUN, sodium, potassium, cholesterol, urine and ultrasound of the kidney. The creatinine clearance was estimated by the Cockcroft-Gault formula, the glomerular filtration rate by the MDRD equation.

220 (60 males/160 females) patients were included. The mean serum creatinine on admisssion and discharge was 1.17 +/- 0.45 mg/dL and 1.11 +/- 0.48 mg/dL respectively. The mean estimated creatinine clearance in the very old was 38.11 +/- 12.04 mL/min on admission and 39.00 +/- 11.01 mL/min on discharge. Renal failure arbitrarily defined as an estimated creatinine clearance on admission of less than 30 mL/min was found in 26.4% of the patients. Only a significant correlation between failure to thrive and renal failure was found (p < 0.0001). The correlation coefficient between the Cockcroft-Gault and the MDRD formula was r = 0.66 (p < 0.0001); between the Cockcroft-Gault and the reciprocal serum creatinine was r = 0.60 (p < 0.0001) and between the MDRD and the reciprocal serum creatinine was r = 0.87 (p < 0.0001).

The weak correlation between the Cockcroft-Gault and other estimations of GFR in the acutely ill elderly, confirms the need to have a reliable estimation of glomerular filtration rate in the elderly. Renal failure defined as a Cockgroft-Gault <30 mL/min is found in 26.4% of the oldest-old admitted to an acute geriatric department. The elderly with renal failure is more often admitted for failure to thrive. No great differences were observed between renal function on admission and discharge.