Protein in urine (proteinuria): what it means, causes, dipstick grades and what to check next

Protein detected on the urine dipstick. Normally negative; the dipstick mainly detects albumin, graded trace to 4+ (roughly 15–30, 30, 100, 300 and 1,000 mg/dL).

Trace amounts are common after exercise, fever, dehydration or standing all day; persistent 1+ or more is confirmed with a urine albumin-to-creatinine ratio and points to kidney filter damage from diabetes, hypertension or glomerular disease.

Full reference table, citations and testing options: Protein in Urine biomarker page.

1. Transient proteinuria — strenuous exercise in the last 24–48 hours, fever and acute illness, dehydration, cold exposure, emotional stress, seizures, a heart-failure flare or a urinary tract infection
2. Orthostatic (postural) proteinuria — protein only after hours upright, absent in a first-morning sample; benign and common in adolescents and young adults
3. Diabetic kidney disease — the most common cause of persistent albuminuria in adults; the UACR rises years before creatinine does
4. High blood pressure — hypertensive nephrosclerosis, usually with modest protein and a slowly falling eGFR
5. Glomerular disease — IgA nephropathy, membranous nephropathy, focal segmental glomerulosclerosis, minimal change disease, lupus nephritis, post-infectious glomerulonephritis; heavy protein, often with blood and casts
6. Preeclampsia — new protein after 20 weeks of pregnancy with a blood pressure of 140/90 or higher; always urgent
7. Tubular and interstitial disease — interstitial nephritis from NSAIDs, proton-pump inhibitors or antibiotics, heavy metals, inherited tubular disorders; small proteins the tubules fail to reabsorb
8. Overflow proteinuria — light chains in multiple myeloma, which the dipstick largely misses; detected by sulfosalicylic acid or urine protein electrophoresis
9. False positives — very alkaline urine (pH above 8), antiseptic contamination (chlorhexidine, benzalkonium), visible blood or pus in the sample, highly concentrated urine

• None at all in most people — protein is found on a routine test
• Foamy or frothy urine when the amount is large
• Swelling of the ankles, legs, hands or around the eyes, and weight gain from fluid, in nephrotic-range protein loss
• In pregnancy: headache, visual disturbance, upper abdominal pain and swelling with the protein — preeclampsia

• Repeat the dipstick on a first-morning, clean-catch sample two or more weeks later, outside illness and exercise — a negative repeat means transient or orthostatic proteinuria
• Quantify a persistent positive with a urine albumin-to-creatinine ratio (below 30 mg/g normal, 30–300 moderately increased, above 300 severely increased) or a protein-to-creatinine ratio
• Serum creatinine with eGFR, a complete urinalysis with microscopy for blood, casts and cells, and a blood pressure reading
• Fasting glucose or hemoglobin A1c, and a lipid panel and serum albumin when the protein is heavy
• A kidney ultrasound and a nephrology referral when the UACR is above 300 mg/g, the eGFR is below 60 or falling, or blood and casts accompany the protein
• Treatment that lowers protein starts at the moderately increased stage — ACE inhibitors or ARBs, SGLT2 inhibitors, blood-pressure and glucose control — so the early finding is the one worth acting on

Follow-up tests available at TestWell: Lipid Panel ($19.99), Hemoglobin A1c Test ($18.99), Glucose Test ($14.99).