In children and adolescents the evaluation of proteinuria is cumbersom
e because of the need to obtain timed urine collections. The protein/c
reatinine ratio (using a Coomassie blue binding technique and a kineti
c Jaffe reaction, respectively) measured in 134 pediatric patients wit
h renal disease aged 2 months to 16 years correlated closely with the
overnight urine protein excretion rates using the statistical approach
suggested by Bland and Altman to compare methods of measuring same qu
antity.;The upper limit of urinary protein/creatinine ratio measured i
n 252 healthy children and adolescents aged 4 to 19 years was shown to
be 19 mg/mmol. No age-related differences in urinary protein excretio
n were noted in healthy subjects. The random urine protein/creatinine
ratio provides an accurate assessment of quantitative protein excretio
n and avoids errors and difficulties associated with timed urine colle
ction.