AKI: Prerenal Vs Intrarenal

A child with several days of vomiting, dry mucous membranes, tachycardia, and scant urine may have functional AKI: glomerular filtration has fallen because the kidneys are underperfused, but the kidney tissue is initially intact. This is the physiology traditionally called prerenal AKI. A child who becomes oliguric after shock, sepsis, a nephrotoxic medication, or prolonged hypoxia may instead have structural AKI, traditionally called intrinsic or intrarenal AKI. Tubules, interstitium, glomeruli, or renal blood vessels have been injured. Acute tubular injury is the common structural pattern after sustained ischaemia or toxic exposure. The distinction guides treatment, but it is not a permanent boundary. Ongoing functional hypoperfusion can progress to tubular injury. A “fluid-responsive” cause that is not corrected promptly may become a kidney-cell injury that no longer reverses simply when perfusion is restored. A third category matters: post-obstructive AKI. Bilateral obstruction, obstruction of a solitary functioning kidney, or an obstructed urinary catheter can raise pressure upstream and reduce filtration. In a child, congenital urinary tract abnormalities, stones, blood clots, or catheter problems may be relevant. Canadian paediatric guidance uses *functional* and...