[Comparative quantitative clinico-chemical analysis of the characteristics of 24-hour urine and morning urine].

Ten clinical chemical parameters were used to investigate the relationship between morning urine and 24-hour urine in 80 healthy probands. During the period of the investigation there were no dietary restrictions. A period of at least 4 hours was required between the previous micturation and the collection of morning urine. The following parameters were determined: sodium, potassium, chloride, creatinine, urea, uric acid, glucose, calcium, inorganic phosphorus and total protein. Every parameter, with the exception of total protein, was determined without prior manual dilution, by a fully mechanized procedure, using a multichannel analyser SMA 12/60 (Technicon) adapted for routine purposes. The data showed: The scatter of the excretory values is generally lower in 24-hour urine than in morning urine, but collectively the reference intervals are relatively wide. Almost without exception, there is a significant correlation between excretion in the 24-hour and morning urines, but the average correlation coefficient is only 0.5. The determined reference intervals (10/90 percentile) for the concentrations of the parameters in 24-hour and morning urines are largely in agreement. It is concluded from the data that the composition of morning urine of apparently healthy probands adequately reflects excretion of 24 hours. It remains to be seen whether this is also true for pathological states.