# Blood in the urine: timing is a clue

IgA nephropathy often causes hematuria during or soon after a respiratory infection, usually with normal complement. Postinfectious GN often follows a symptom-free interval, whose length depends on the infection, with low C3. Neither pattern proves etiology. Dysmorphic red cells, red-cell casts and protein raise concern for glomerular injury. Assess BP, creatinine trend, potassium, urine output and pulmonary symptoms. Rapid deterioration, pulmonary bleeding, severe hypertension, oliguria or hyperkalemia require urgent escalation and focused nephrology-directed testing. Follow BP, kidney function, protein and complement recovery; persistent abnormalities need reassessment.

[KDIGO glomerular disease guidance](https://kdigo.org/guidelines/gd/)

Andrew Bland, MD, FACP, FAAP