[Use of the Cocroft and Gault formula for evaluation of 24-hour urinary excretion of electrolytes].
Measurement of 24-hour electrolyte elimination requires exact urine collection over the period or study and cooperation of the individual being examined. These conditions are often not fulfilled. In an effort to be able to assess 24-hour elimination of Na+ and K+ in situations where urine collection is not absolutely complete, we developed a formula allowing to calculate the urinary elimination of the monitored electrolyte on the basis of its urinary concentration, urinary creatinine concentration, and urinary creatinine excretion using Cocroft and Gault's formula. The proposed formula is as follows: [formula: see text] This formula applies to men, when using it in women, a factor of 0.0015 has to be used instead of 0.0018. The method was used to measure urinary Na+ and K+ elimination in 60 hospitalized individuals after renal transplantation. Significant linear correlations were found between the values obtained by careful urine collection and the calculated (predicted) values using the above formula: r = 0.939, p < 0.001 with Na+ and r = 0.924, p < 0.001 with K+. The results provide support to the assumption that calculation of urinary Na+ and K+ elimination using the above formula may be useful in cases where urine collection over a period of 24 hours is not absolutely complete. (Tab. 1, Fig. 4, Ref. 2.)
Schuck
O
O
Institute of Clinical and Experimental Medicine, Prague, Czech Republic.
Marusova
L
L
Lanska
V
V
D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D008962:Models, Theoretical; D011188:Potassium / Q000652:urine*; D012964:Sodium / Q000652:urine*
D012964:Sodium; D011188:Potassium