A child presents with hematuria, hypertension, and periorbital edema. What is the most likely diagnosis?

The presentation of hematuria, hypertension, and periorbital edema in a child is highly indicative of post-streptococcal glomerulonephritis (PSGN). This condition often follows a streptococcal infection, particularly a recent skin or throat infection. The classic symptoms arise due to the inflammatory response in the glomeruli of the kidneys, leading to changes in kidney function.

Hematuria results from glomerular inflammation which disrupts the filtration barrier, allowing red blood cells to leak into the urine. Hypertension commonly occurs due to fluid overload and increased extracellular fluid volume caused by the kidneys' impaired ability to excrete sodium and water effectively. The periorbital edema is particularly characteristic in children with PSGN, as fluid retention is more visibly apparent in areas with loose connective tissue, such as around the eyes.

In contrast, IgA nephropathy typically presents with hematuria following infections but is not as commonly associated with periorbital edema or hypertension as prominently as PSGN, and it often has a more chronic course. Minimal change disease primarily presents with nephrotic syndrome features, such as significant proteinuria and edema, rather than the specific triad seen in this case.