The most common type of acute renal failure in neonates is:

• A. Prerenal
• B. Intrinsic
• C. Postrenal
• D. Glomerular Disease

Answer: (A)

In neonates, the most common type of acute kidney injury is due to decreased renal perfusion, known as prerenal azotemia. This happens when blood flow to the kidneys is reduced from factors like volume depletion, sepsis, hypotension, or perinatal asphyxia. Because the kidney itself isn’t primarily damaged, restoring perfusion quickly reverses the dysfunction, making this the frequent scenario in newborns. Clinically, you’d see signs of reduced effective circulating volume and oliguria, with laboratory patterns often showing a preserved or high BUN/creatinine ratio and a low fractional excretion of sodium, reflecting the kidney’s attempt to hold onto sodium and water.

Intrinsic renal disease, such as acute tubular necrosis, stems from direct injury to kidney tissue and is less common in neonates, though it can occur after severe illness or nephrotoxin exposure. Postrenal obstruction due to congenital urinary tract anomalies is possible but relatively rare in the newborn period. Glomerular diseases are uncommon in this age group.

So the key idea is that neonatal AKI most often arises from reduced kidney perfusion rather than primary kidney injury.