Proteinuria

The abnormal urinary excretion of increased amounts of protein, most commonly albumin, reflecting glomerular or tubular dysfunction and serving as a marker of renal disease or systemic pathology. Either measured with a 24-hour urine collection or a spot urine test of albumin-to-creatinine ratio (ACR).

• Normal: <150 mg/day (ACR <3 mg/mmol)

• Microalbuminuria (Mild): 30 - 300 mg/day (ACR 3 - 30 mg/mmol)

• Moderate: 300 mg - 3.5 g/day (ACR >30 mg/mmol)

• Nephrotic syndrome: >3.5 g/day (ACR >300 mg/mmol)

Causes

• Renal disorders causing impaired protein reabsorption

  • Chronic kidney disease

  • Glomerulonephritis

  • Nephrotic syndrome

  • Diabetic nephropathy

  • Hypertensive nephropathy

  • Lupus nephritis

• Systemic and vascular causes

  • Heart failure

  • Multiple myeloma

  • Systemic inflammatory diseases

• Urinary tract infection

• Other causes

  • Transient proteinuria due to fever, exercise, dehydration, or acute illness

  • Pregnancy-related renal changes