To the Editor.
—Although well documented in the medical literature,1,2 the effect of diet on the creatinine clearance is often overlooked. Creatinine is present in meat and is absorbed to a substantial extent from the gastrointestinal tract. Cooking of foods for prolonged periods seems to enhance conversion of creatine to creatinine.3 Because of the recent popularity of "slow cooker" electric crock pots, I undertook a brief study. Five-hour collections of urine were obtained after a beef meal cooked for eight hours and, several days later, after a dairy meal. The first collection contained 565 mg of creatinine in a volume of 480 mL, while the second collection had 382 mg of creatinine in a volume of 530 mL. With a fasting serum creatinine level of 1.2 mg/dL, the calculated creatinine clearance was 158 mL/min after the meat meal and 107 mL/min after the dairy meal.While the fact