Renal excretion

Renal excretion

Kidney function is not mature in young children. The renal blood flow and filtration rate of the glomeruli is still low. The renal blood flow matures between the age of 5 to 12 months. The glomerular filtration rate reaches normal levels after 5 months. The resorption in the tubules is mature around 7 months of age.

Due to this difference

in timing of maturity of the different components of renal function, some drugs show a normal excretion pattern earlier than others.

Example:

digoxin and gentamicin (glomerular secretion) show a normal excretion pattern around 5 months, while penicillins (tubular excretion) are excreted normally after 7 months of age.

1

Since most drugs undergo glomerular secretion, neonates have a lower rate of renal excretion. 

2

A normal glomerular filtration rate is reached after 5 months of age and is