KIDNEY-TO-LIVER RATIO - A SIMPLE SCINTIGRAPHIC PARAMETER FOR ROUTINE INDIVIDUAL RENAL-FUNCTION ASSESSMENT IN CHILDREN

DTPA renography is commonly used for measuring relative renal function . However, in patients with bilateral renal disease or solitary kidney s, split function studies are of no value. Available techniques to qua ntify individual renal function are either time consuming or inaccurat e. The authors validate the kidney-to-liver ratio at 3 minutes (K3/L3) as an index of renal function, showing excellent correlation with GFR . Normal K3/L3 ranges were then computed In 113 pediatric kidneys (age 2 days to 16 years) and 24 adults. Indicative of renal maturation, th e K3/L3 rapidly rose from a value of 1.32 at birth to 2.02 at 6 months . Subsequently, ft increased slowly to reach a peak of 2.34 at age 2, followed by gradual decline to adult values after age 5. This decrease is due likely to continued growth of the hepatic blood pool after ren al maturation. GFR followed the same maturation pattern to reach a pla teau around 2 years of age. K3/L3 reflects individual kidney function, and it requires no blood sampling or urine collection. By establishin g normal values at different stages of maturity, this method provides identification and quantification of renal dysfunction in infants, chi ldren, and adults.