ON THE DETERMINANTS OF THE CREATININE CLEARANCE - A POPULATION STUDY

The objective of this study was to define the normal urinary creatinin e clearance and its determinants. The creatinine clearance was measure d in both sexes in a large random Belgian population sample (BIRNH: Be lgian Interuniversity Research on Nutrition and Health) by measuring s erum creatinine and the 24 h urinary creatinine excretion. At a mean a ge of 50.8 years in 2,075 men and 50.1 years in 1,933 women the mean c reatinine clearance was 101 +/- 30.5 and 86.9 +/- 25.8 ml/min respecti vely. In multiple regression analysis the creatinine clearance in both sexes correlated negatively with age and positively with weight and 2 4 h urinary sodium, potassium, calcium and magnesium (all P < 0.0001), Total R(2) was 0.40 in men and 0.35 in women. After adjustment for ag e, height and weight no significant relationship exists between the 24 h urinary creatinine clearance and either systolic or diastolic blood pressure. Serum creatinine increased with age, more so in women, and was at all ages higher in men compared to women. The creatinine cleara nce decreased with age in both sexes. Our study demonstrates the exist ence of highly significant associations between urinary cations and th e creatinine clearance, independent of total caloric intake.