[Use of MDRD equation to detect occult renal failure and reduce the risk of digitalis overdose].

INTRODUCTION: Digoxin overdose is closely related to Chronic Kidney Disease and creatinine dosage adjustment is usually needed. Our goal was to assess the advantages of serum creatinine and the MDRD equation to detect hidden renal insufficiency to reduce the overdose Digital risk.

METHODS: We describe all digoxin samples processed and registered in our hospital laboratory database for a year. Patients under 18 years and samples below therapeutic ranges were excluded. Chi square (p<0.05), ROC curves and logistic regression analysis were conducted. SPSS software was used.

RESULTS: Between 1228 digoxin samples taken to 679 patients (273 men, 77 +/- 10 years old , and 406 women 82 +/- 8 years old), 14% were over therapeutic range (28 men and 67 women). Significant differences were observed in over dosage between high creatinine group regarding to normal creatinine group (31% vs. 10% in men, 44% vs. 15% in women). ROC curves showed that the most accurate levels to predict digoxin over dosage were MDRD<56 ml/min/1.73 m(2) in men and MDRD<52 ml/min/1.73 m(2) in women. 68% of over dosage men had declines of MDRD levels, compared to 61% with high creatinine levels, 81% of over dosage women had declines of MDRD compared to 51% with elevated creatinine levels.

CONCLUSIONS: Even in patients with normal creatinine levels, chronic kidney disease enhances digoxin over dose risk. Using the decline of glomerular filtration rate estimated by the MDRD equation is better than elevated creatinine levels to detect digoxin overdose, thus constituting a very useful tool to reduce the risk of overdose, especially among women.