Frothy urine

Specialty: Nephrology and urology.

• macroscopic proteinuria
• persistent foam in the urine

Why it occurs

• Nephrotic syndrome (glomerulopathies such as membranous nephropathy, minimal change disease or focal segmental glomerulosclerosis with massive albumin loss)
• Diabetic nephropathy (advanced glomerular microvascular damage with micro and macroalbuminuria)
• Lupus glomerulonephritis (deposition of immune complexes in the glomerulus due to the activity of systemic lupus erythematosus)
• Renal amyloidosis (extracellular deposition of amyloid fibrils that disrupt the glomerular filtration barrier)
• Malignant arterial hypertension (glomerular endothelial damage induced by extremely high systemic pressures)

Initial workup

Urine test strip for semi-quantification of proteins; 24-hour urine collection to quantify total protein and creatinine clearance, or determination of the protein/creatinine ratio (UPCR) or albumin/creatinine ratio (UACR) in an isolated first morning urine sample; serum quantification of albumin, total proteins and lipid profile; Ultrasound-guided percutaneous renal biopsy for definitive histopathological diagnosis if nephrotic range proteinuria (>3.5 g/24h) without obvious systemic cause is confirmed.

Standard management

• Enalapril — 5-20 mg every 12 hours orally, ACE inhibitor to reduce intraglomerular pressure through vasodilation of the efferent arteriole, reducing proteinuria; monitor potassium and creatinine) or Losartan (50-100 mg daily, angiotensin II receptor antagonist as an alternative if you have cough due to ACE inhibitors
• Furosemide — 20-80 mg daily orally for the management of edema, adjusting according to fluid balance
• Atorvastatin (20-40 mg daily for the management of hypercholesterolemia secondary to nephrotic syndrome).