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Blood Test Tracker

Urine Protein (Dipstick)

A strip test that gives a rough estimate of the protein in your urine, reported as negative, trace, or 1+ to 4+.

AI-verified against cited sources. Awaiting expert reviewAlso called PRO, PROTLOINC 20454-5

What it is

Healthy kidneys keep most protein in your blood, so only a small amount reaches your urine. A test strip dipped in your urine changes color when protein is there, and the lab reports how strong the color is: negative, trace, then 1+ to 4+. Some labs print the matching amount in mg/dL instead. The strip mostly reacts to albumin, the main protein that leaks through damaged kidney filters. It is a quick check, not an exact measurement.

Why it matters

Protein in the urine can be one of the earliest signs that the kidney filters are under strain. It can show up before you feel any symptoms. Small amounts are also common for harmless, short-lived reasons such as exercise, fever or concentrated urine. Because the strip is a rough tool, a positive result is usually followed by a repeat sample and a lab test called ACR or PCR, which compares protein to creatinine. What matters most is whether protein keeps showing up over several months.

If it’s high

A reading of 1+ or higher means the strip found more protein than usual in that sample. Often this is temporary. If protein keeps showing up on repeat samples, it can be a sign that the kidney filters are under strain, and your clinician may order more tests. A higher grade means more protein, but a strip cannot tell you the cause.

Common causes

  • Dehydration or very concentrated urine
  • Hard exercise
  • Fever or illness
  • Standing for a long time (orthostatic proteinuria), which goes away after lying down
  • Emotional or physical stress
  • Pregnancy, including preeclampsia, which clinicians follow closely
  • A urinary tract infection
  • Menstrual blood or vaginal fluid in the sample
  • Kidney damage from conditions such as diabetes, high blood pressure or inflammation of the kidney filters
  • Heart failure
  • Less often, bladder problems or unusual proteins in the blood, such as in multiple myeloma

What can help

  • Ask your clinician about repeating the test on a first-morning sample
  • Ask whether a urine albumin-to-creatinine ratio (ACR) is a good next step
  • If you have diabetes or high blood pressure, ask how often your kidneys and urine protein should be checked

What can affect your result

  • Urine concentration: strips do not adjust for how dilute or concentrated the urine is
  • Exercise, fever, stress and long periods of standing
  • Menstrual blood and vaginal discharge in the sample
  • Urinary tract infection
  • Pregnancy
  • X-ray contrast dye in the 3 days before the test
  • Strip brand: makers match color grades to mg/dL differently
  • Type of protein: strips react mostly to albumin and can miss other proteins
  • Dehydration or very concentrated urine can make the reading higher, and very dilute urine can hide a low level of protein.
  • Hard exercise, fever and stress can cause temporary protein in the urine.
  • Menstrual blood or vaginal fluid in the sample can add protein.
  • A urinary tract infection can add protein.
  • X-ray contrast dye (given for a scan) in the 3 days before the test can affect the result.
  • Phenazopyridine (a urinary pain-relief medicine) and quaternary ammonium compounds (found in some antiseptics and disinfectants) can make the strip read falsely high.
  • Strips react mostly to albumin and can miss other proteins, such as light chains (Bence Jones proteins).
  • Strip brands match color grades to mg/dL differently, and there is no standard between manufacturers.

A first-morning sample is preferred when protein is being followed up, because it varies less within a person and helps rule out protein that appears only when you are upright. A random sample is acceptable if a first-morning one is not available. A strip shows the protein in the sample you gave that day. Temporary causes such as exercise or fever may be gone on a repeat sample. Kidney damage is judged by results that last at least 3 months.

When to talk to a clinician

Talk with your clinician soon about any result of 1+ or higher, or if protein shows up again on a repeat sample. Contact a clinician promptly if protein comes with swelling in your hands, feet or around your eyes, foamy or bloody urine, or shortness of breath. If you are pregnant, tell your clinician about any positive protein result.

Questions you could ask

  • Given my health history, should my kidneys also be checked with a blood test such as eGFR?
  • Should we repeat this on a first-morning sample?
  • Would a urine albumin-to-creatinine ratio (ACR) or protein-to-creatinine ratio (PCR) give a clearer picture?
  • Could exercise, dehydration, a recent illness or how I collected the sample explain this?
  • How often should my kidney function and urine protein be checked?

Questions people ask

What do trace, 1+, 2+, 3+ and 4+ mean?

They are grades of color on the strip. Roughly, trace is 5 to 10 mg/dL, 1+ is about 30, 2+ about 100, 3+ about 300 and 4+ about 1,000 mg/dL. Brands differ, and the strip does not adjust for how dilute your urine is, so treat the grade as a rough guide.

My dipstick was negative or trace. Does that rule out protein loss from the kidneys?

No. Strips can miss small amounts of albumin and other proteins, and dilute urine can hide protein. For people at risk of kidney disease, guidelines prefer a lab test of albumin against creatinine (ACR) over a strip.

Can exercise, dehydration or a fever cause protein in my urine?

Yes. These are common, short-lived causes. If protein is found, your clinician may ask you to repeat the test on another day, ideally with a first-morning sample.

What is orthostatic proteinuria?

It is a benign form where protein appears in the urine after you have been upright for a long time and is gone after you have been lying down. A first-morning sample, collected after hours of lying down, helps tell it apart from other causes.

Why does my lab report mg/dL instead of plus signs?

Some labs print the amount that matches each grade, such as 30, 100 or 300 mg/dL, rather than 1+, 2+ or 3+. Others use +, ++ and +++. They are describing the same strip reading. Ask your lab if you are unsure how to read yours.

Show the science and sources

For clinicians and researchers

Protein pads respond mainly to albumin and can miss low-molecular-weight proteins such as light chains (Bence Jones proteins) and low concentrations of globulins (AFP 2022, AFP 2005). Approximate protein equivalents per grade are trace 5-10, 1+ 30, 2+ 100, 3+ 300 and 4+ 1,000 mg/dL (AFP 2022 Table 4). Brands differ, and many labs print mg/dL (for example 30, 100, 300) instead of plus signs. KDIGO 2012 Table 7 maps reagent strip results to proteinuria categories: negative to trace corresponds to A1 (PCR below 150 mg/g), trace to + to A2 (PCR 150-500 mg/g), and + or greater to A3 (PCR above 500 mg/g), with the caveat that the relationship is approximate and depends on urine concentration. KDIGO 2024 states that strips measuring total protein are insufficiently sensitive, do not adjust for urinary concentration, are only semiquantitative and are not standardized between manufacturers, and advises confirming positive strips with a laboratory ACR or PCR. False positives come from alkaline or concentrated urine, phenazopyridine and quaternary ammonium compounds. False negatives come from dilute or acidic urine and from non-albumin proteinuria (AFP 2022 Table 2). Labcorp prints 'Negative/Trace' as the reference for this line. In a tertiary-center cohort of 11,229 patients, dipstick protein alone had an AUC of 0.77 for a urine ACR of 30 mg/g or more or a PCR of 0.15 g/g or more, rising to 0.82 when specific gravity was added (McAdams 2024). A first-morning sample is preferred because it correlates well with 24-hour excretion, varies less within a person and is required to exclude orthostatic proteinuria (KDIGO 2024). Chronic kidney disease requires abnormalities present for at least 3 months.

LOINC 20454-5 (primary), 5804-0, 57735-3, 50561-0, 2887-8. Specimen: urine.

Sources

  1. Protein in Urine, MedlinePlus (U.S. National Library of Medicine)
  2. Urine protein dipstick test, MedlinePlus Medical Encyclopedia (U.S. National Library of Medicine) (2025)
  3. Office-Based Urinalysis: A Comprehensive Review, American Family Physician 2022;106(1):27-35B (2022)
  4. Urinalysis: A Comprehensive Review, American Family Physician 2005;71(6):1153-1162 (2005)
  5. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, Kidney International 105(4S):S117-S314 (2024)
  6. KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease, Kidney International Supplements 2013;3(1):1-150 (2013)
  7. Specific Gravity Improves Identification of Clinically Significant Quantitative Proteinuria from the Dipstick Urinalysis, Kidney360 2024 (2024)
  8. Urinalysis: What It Is, Purpose & Results, Cleveland Clinic (2024)
  9. Urinalysis, Complete With Microscopic Examination (test 003772), Labcorp
  10. Urinalysis, Complete (test 003772) sample patient report with reference intervals, Labcorp (2026)
  11. LOINC codes verified with the NLM Clinical Tables LOINC search (e.g. 20454-5), U.S. National Library of Medicine

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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