Eighty measurements of plasma creatinine concentration, height:creatinine ratio, 
and plasma beta 2 microglobulin concentration were made on 72 children (age 4 
months-18.5 years) with known renal disease. Results were compared with 
simultaneous measurements of glomerular filtration rate using plasma clearance 
of 51Cr edetic acid to assess the performance of each test as an initial 
screening procedure of renal insufficiency. Height:creatinine index less than 
2.1 was found to have a higher sensitivity and predictive value of a normal 
result than the other tests and is therefore the preferred test for a screening 
procedure.