Variation of protein content of urine in a 24-hour period.

Variation of the protein content in urine of patients known to excrete protein in excessiveamountswas studied. Variation in different specimensobtained from the same patient on a particular day and from day to day were studied. A total of 293 urine specimensexcreted over a 3to 6-day period by 25 patients were examined. No particular pattern of protein excretion was observed. The morning specimen was not the specimen with the highest protein content. This could occur at any time during the day. It is suggestedthat only a 24-hour collection can give a true indication of protein spillage. A commercial paper strip test was compared with the qualitative sulfosalicylic acid reaction and a quantitative biuret procedure. The strip test is satisfactory for screeningpurposesexcept for highly colored urines, in which case the sulfosalicylic acid procedure is recommended.