Multiple overnight urine collections may be used for estimating the excretion of electrolytes and creatinine.
We studied the excretion of sodium, potassium, calcium, magnesium, and creatinine in overnight and 24-h urines collected over a period of seven consecutive days from 28 Dutch boys, ages eight and nine years. The correlation coefficients for the relation between true mean overnight and true mean 24-h excretion ranged between 0.94 and 1.00 for sodium, calcium, magnesium, and creatinine and was equal to 0.61 for potassium. Generally the within-person coefficients of variation for overnight excretions (range, 33-52%) were greater than for 24-h excretions (range 16-35%). We conclude that overnight collections may replace 24-h collections in the case of young boys, but that generally more overnight than 24-h urine specimens are required to achieve a similar degree of precision. The exact number of urine specimens required varies with the aims of the study.
Knuiman
J T
JT
Department of Human Nutrition Wageningen Agricultural University, The Netherlands.
van Poppel
G
G
Burema
J
J
van der Heijden
L
L
Hautvast
J G
JG
D002118:Calcium / Q000652:urine; D002648:Child; D003404:Creatinine / Q000652:urine*; D004573:Electrolytes / Q000652:urine*; D006801:Humans; D008274:Magnesium / Q000652:urine; D008297:Male; D011188:Potassium / Q000652:urine; D012964:Sodium / Q000652:urine; D013048:Specimen Handling; D013223:Statistics as Topic
D004573:Electrolytes; D012964:Sodium; D003404:Creatinine; D008274:Magnesium; D011188:Potassium; D002118:Calcium