Protein in Urine: What Does It Mean and What Happens Next?

Protein in urine means the test found more protein than the small amount urine normally contains. Healthy kidney filters keep most protein, especially albumin, in the blood. A raised result can be temporary, or, if it persists on repeat testing, it can be a sign that the kidneys are damaged.

This guide is for adults who have been told a urine test showed protein. It explains common causes, the tests involved and what to ask. It cannot tell you why your result was raised or whether you have kidney disease.

If you are pregnant or gave birth in the last few weeks and protein was found in your urine, follow your maternity team's advice promptly. The NHS lists protein in urine with high blood pressure as an early sign of pre-eclampsia. Seek urgent help through your maternity unit, or local urgent services, for a severe headache, vision changes such as blurring or flashing lights, pain below the ribs, vomiting, or sudden swelling of the face, hands or feet.

Outside pregnancy, Cleveland Clinic advises contacting a healthcare provider for these symptoms with protein in urine:

• Swelling of the face, belly, legs or feet.
• Shortness of breath.
• Dizziness, weakness or feeling lightheaded.
• Passing urine much more often than usual, or pain when passing urine.

Most people with protein in urine have no symptoms, which is why it is usually found on a routine test. When symptoms do occur, Cleveland Clinic and the National Kidney Foundation describe foamy or bubbly urine and swelling, for example puffiness around the eyes in the morning or swollen ankles.

Causes fall broadly into temporary and longer-lasting groups. MedlinePlus notes that levels can rise briefly without an underlying disease. Cleveland Clinic and the National Kidney Foundation list similar temporary triggers, while persistent protein is more often linked to long-term conditions.

• Temporary: strenuous exercise, dehydration, fever or infection, stress and, according to Cleveland Clinic, cold exposure.
• Positional (orthostatic): more protein after standing for long periods and normal after lying down; Cleveland Clinic notes this can occur in younger people.
• Longer-lasting: diabetes, high blood pressure, heart disease or heart failure, and conditions that inflame the kidney filters (glomerular disease).
• Less common: autoimmune conditions such as lupus, multiple myeloma, and some medicines or toxins. Do not stop a prescribed medicine yourself; discuss it with the prescriber.

A dipstick is a chemical strip that changes colour when protein is present. It is quick and often part of a routine urinalysis, but it gives an approximate reading.

The albumin-creatinine ratio (ACR, also called uACR) measures albumin, the main protein leaked by damaged kidney filters, and compares it with creatinine in the same sample. NIDDK explains that this ratio helps estimate how much albumin would pass into the urine over a whole day, without a 24-hour collection. Some services use a protein-creatinine ratio (PCR) instead, or ask for a 24-hour urine collection because protein levels vary through the day.

Units differ by country, so check which one your report uses. In US units, NIDDK describes a result of 30 mg/g or less as normal, and the National Kidney Foundation calls 30 to 299 mg/g moderately increased and 300 mg/g or higher severely increased. The NHS uses mg/mmol: under 3 is category A1, 3 to 30 is A2 and over 30 is A3.

These categories describe the urine result only. Kidney function also depends on the blood test eGFR, and the two are read together. For a single low eGFR, see the separate guide on that result. Always use the reference range on your own report, as labs differ.

Usually not. Because protein can rise briefly, a single raised result is normally confirmed. NIDDK says the test may be repeated one or two more times. The National Kidney Foundation suggests repeating a first raised ACR within 3 to 6 months and notes that a result confirmed above the normal range within that time may indicate kidney disease, even when eGFR is normal.

Tell the clinician about anything that might have affected the sample, such as hard exercise, fever, an infection or dehydration. Ask whether a first-morning sample is wanted and follow the service's collection instructions.

Persistent protein usually prompts a look for a cause and a plan for monitoring. The NHS advises regular testing for people with protein or blood in the urine without a known cause, and for higher-risk groups such as people with diabetes, high blood pressure, cardiovascular disease or a family history of kidney disease. NIDDK advises yearly urine albumin checks for people with diabetes.

Further assessment may include blood tests, blood pressure and blood sugar checks, an ultrasound of the kidneys and, in some cases, referral to a kidney specialist. Drinking extra water does not treat proteinuria, according to Cleveland Clinic. Treatment, if needed, targets the underlying cause.

Bring copies of urine and blood results, including earlier ones. These questions can help clarify the plan.

• Was protein found on a dipstick only, or was an ACR or PCR measured? What was the number and unit?
• Could exercise, fever, infection or dehydration have affected this sample?
• When should the test be repeated, and how should I collect the sample?
• What did my eGFR, blood pressure and blood sugar show?
• If protein persists, what will you look for next, and how often will it be monitored?
• Which symptoms should make me seek help before the next review?

On SameCase, patients and verified doctors share de-identified cases. Reading how others with protein in urine were followed up, such as how repeat tests were timed or which results their clinician asked about, can help you prepare questions.

Similar cases cannot interpret your result or predict what will happen. Use them to prepare for appointments, and rely on your own clinician for decisions.