Factors associated with creatinine clearance changes following gentamicin therapy

The relationship between creatinine clearance changes during gentamicin therapy and several patient and therapeutic variables was studied in a prospective, multicenter trial. Adult patients in three hospitals who were receiving gentamicin in doses based on lean body weight and creatinine clearance were studied. Pre- and post-therapy serum creatinine measurements were obtained for 62 patients (Group 1); only 45 of the patients had both pre- and post-therapy creatinine clearance measurements (Group 2). Other data collected for correlation with creatinine clearance changes were: body temperature, age, sex, blood pressure, albumin level, previous and concomitant therapy with nephrotoxic drugs, hematocrit, peak and trough gentamicin levels, and duration of therapy. In Group 2 patients, only peak gentamicin level, concomitant therapy, sex, and previous furosemide therapy correlated significantly (p less than or equal to 0.05) with change in creatinine clearance during gentamicin therapy. The first two variables decreased creatinine clearance, the last variable increased creatinine clearance, and women tended to have more of a decrease in clearance than did men. Sex, peak gentamicin level, prior furosemide therapy and concomitant cephalothin therapy explain about 50% of the renal function changes during gentamicin therapy, and should be considered in monitoring gentamicin therapy.