Renal hypoplasia

Renal hypoplasia
Other names	Hypoplastic kidneys
An ultrasound scan of a hypoplastic right kidney in an adult male.
Specialty	Nephrology
Complications	Anuria, chronic kidney disease, glomerular hyperfiltration, hypertension, proteinuria, sepsis, urinary tract infection, urinary tract obstruction, urolithiasis[1][2]
Types	Simple, oligomeganephronic, segmental, cortical
Causes	Mutation of the genes HNF1B, PAX2, PBX1[1]
Diagnostic method	Ultrasound
Differential diagnosis	Renal dysplasia, oligomeganephronia[3]
Frequency	1 in 400 births[4]

Renal hypoplasia is a congenital abnormality in which one or both of the kidneys are smaller than normal,^[5] resulting in a reduced nephron number^[1] but with normal morphology.^[4]

It is defined as abnormally small kidneys, where the size is less than two standard deviations below the expected mean for the corresponding demographics, and the morphology is normal.^[4][1] The severity of the disease depends on whether hypoplasia is unilateral or bilateral, and the degree of reduction in the number of nephrons.^[1]