Kidney Health 9 min read·Updated 22 July 2026 Clinician-reviewed

Protein in Urine (Proteinuria)

A UK Consultant Nephrologist on what protein in urine means, why it is one of the most important early markers of kidney disease, and the steps your GP or renal team will take.

  • Clinically Reviewed
  • NHS & NICE Aligned
  • UK Evidence-Based
  • Last Reviewed 22 July 2026

Professor Mohammed Mahdi Althaf

Consultant Nephrologist & Acute Physician

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Professor Mohammed Mahdi Althaf

MD, MSc, PgDip (Clin Ed), FRCP, FHEA, FASN

Consultant Nephrologist & Acute Physician · GMC 7216325

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Direct answer

Protein in urine (proteinuria) is an early warning sign that kidney filters are damaged. It is measured by urine ACR. Persistent A2 or A3 proteinuria needs blood-pressure control, often ACE inhibitors/ARBs, diabetes management, and sometimes referral to nephrology.

Key recommendation: Proteinuria = leaky kidney filters; predicts CKD and heart risk.

Quick answer

✓ Best choices

  • Plant proteins: tofu, tempeh, beans, lentils, chickpeas
  • Eggs and oily fish
  • Lean chicken or turkey in measured portions

✓ Foods to limit

  • Processed meats with phosphate additives
  • Very large daily servings of red meat
  • Unsupervised high-protein shakes and powders

Key takeaway

Protein in urine (proteinuria) is an early warning sign that kidney filters are damaged. It is measured by urine ACR. Persistent A2 or A3 proteinuria needs blood-pressure control, often ACE inhibitors/ARBs, diabetes management, and sometimes referral to nephrology.

Who should be cautious

People on dialysis, post-transplant, pregnant or breastfeeding, or taking prescription medication — confirm with your renal team before changes.

Protein in Urine (Proteinuria)

Why proteinuria matters

Healthy kidney filters keep albumin (the main blood protein) in the bloodstream. When filters are damaged — by diabetes, high blood pressure, inflammation or other diseases — albumin leaks into urine. Proteinuria is both a marker of existing kidney damage and a driver of further damage. People with proteinuria have a higher risk of CKD progression and cardiovascular events, even if eGFR is normal.

How proteinuria is measured

The NHS standard is the urine ACR (albumin-creatinine ratio) on an early-morning urine sample. ACR corrects for urine concentration, making it more reliable than a simple dipstick. Dipstick 'trace' or '+' results should be confirmed with ACR. NICE recommends ACR testing for adults with diabetes, hypertension, or any risk factor for CKD.

Kidney Vitality is a daily multivitamin developed using renal nutrition principles. It sits alongside food, not in place of it. See the formulation.

Causes of protein in urine

Common causes: diabetic kidney disease (the most common cause of proteinuria in the UK), high blood pressure nephropathy, glomerulonephritis (inflammation of the kidney filters), minimal change disease, IgA nephropathy, and less commonly myeloma or amyloid. Transient causes: UTI, fever, strenuous exercise, dehydration, and heart failure.

What your GP will do

  1. Repeat the ACR to confirm persistence. 2. Check eGFR, full blood count, blood glucose/HbA1c, lipids, and blood pressure. 3. Review medications (NSAIDs, some herbal supplements). 4. Start or optimise ACE inhibitor or ARB if BP allows — these reduce protein leak. 5. Refer to nephrology if ACR > 70, eGFR < 30, or if the cause is unclear.

What you can do

Keep blood pressure well controlled (home monitoring helps). Reduce salt to under 6 g/day. Keep diabetes well controlled if applicable. Avoid regular NSAID use (ibuprofen, naproxen). Do not smoke. Maintain a healthy weight. These steps reduce proteinuria and slow CKD progression.

Stages of Kidney Disease Explained
Related reading: Stages of Kidney Disease Explained.

Key practical tips

Designed for quick scanning — what to order, what to avoid, sensible portions, common mistakes.

  • Use the palm of your hand as a protein portion guide
  • Distribute protein across the day, not all in one meal
  • Confirm your target with your renal dietitian — it changes by stage

Clinical guidance

TL;DR summary

Protein in urine (proteinuria) is an early warning sign that kidney filters are damaged. It is measured by urine ACR. Persistent A2 or A3 proteinuria needs blood-pressure control, often ACE inhibitors/ARBs, diabetes management, and sometimes referral to nephrology.

Key takeaways
  • Proteinuria = leaky kidney filters; predicts CKD and heart risk.
  • Urine ACR is the standard NHS test: A1 normal, A2 moderate, A3 severe.
  • Transient proteinuria happens after exercise, fever or UTI.
  • ACE inhibitors and ARBs reduce protein leak and protect kidneys.
  • Persistent proteinuria on repeat testing needs investigation.
Kidney Diet & Nutrition Considerations

Protein needs in CKD are individual. Most adults with CKD stages 3–4 do well on 0.6–0.8 g/kg/day; people on dialysis usually need 1.0–1.2 g/kg/day. Quality matters: a Mediterranean-style mix of plant protein, fish, eggs and modest poultry generally outperforms a meat-heavy diet for kidney protection.

Foods to prioritise

  • Plant proteins: tofu, tempeh, beans, lentils, chickpeas
  • Eggs and oily fish
  • Lean chicken or turkey in measured portions

Foods to limit

  • Processed meats with phosphate additives
  • Very large daily servings of red meat
  • Unsupervised high-protein shakes and powders

Potassium, phosphate and protein needs vary between individuals — please confirm personal targets with your renal team or dietitian. Browse the Kidney Diet Hub for more guides in this cluster.

Frequently asked questions

What does protein in urine mean?

Protein in urine — called proteinuria — means the kidney filters are leaking albumin into the urine. It is one of the earliest signs of kidney damage and a strong predictor of CKD progression and cardiovascular risk.

What is a normal urine ACR?

Urine ACR (albumin-creatinine ratio) categories: A1 = < 3 mg/mmol (normal to mildly increased); A2 = 3–30 mg/mmol (moderately increased); A3 = > 30 mg/mmol (severely increased). Persistent A2 or A3 needs investigation.

Can exercise or a cold cause protein in urine?

Yes — transient proteinuria can occur after vigorous exercise, fever, dehydration, a urinary tract infection, or a cold. This is why GPs repeat the test — a single positive dipstick is not diagnostic. Persistent proteinuria on two or more tests 1–2 weeks apart is more significant.

How is proteinuria treated?

Treatment targets the cause and protects the kidneys. Common steps: blood pressure control (often with ACE inhibitors or ARBs, which also reduce protein leak), diabetes optimisation, statin therapy for cardiovascular risk, salt reduction, and avoiding nephrotoxic drugs. In some cases a kidney biopsy is needed to find the underlying disease.

How much protein should I eat with kidney disease?

Most adults with CKD stages 3–4 do well on around 0.6–0.8 g of protein per kilogram of body weight per day, while adults on dialysis usually need 1.0–1.2 g/kg/day. Your exact target should be set by your renal dietitian based on your stage, weight and bloods.

Nutritional challenges in kidney disease

Many people living with kidney disease have to limit foods because of potassium, phosphate, diabetes, dialysis, appetite changes or simply the time it takes to cook from scratch every day. That can make it harder to keep daily nutrition balanced — particularly for vitamins and minerals that food alone may not fully cover.

Kidney Vitality is a UK-formulated daily nutritional support product designed by Consultant Nephrologist Professor Mohammed Mahdi Althaf with renal nutrition in mind from the start. It keeps doses moderate, leaves out added potassium, phosphate and magnesium, and avoids megadose vitamin A — sitting alongside a kidney-friendly diet, not replacing it.

Why Kidney Vitality fits this need

Built around UK renal guidance

Aligned with NICE NG203, KDIGO 2024 and UK Kidney Association proteinuria guidance.

Designed by a UK Consultant Nephrologist

Formulated and reviewed by Professor Mohammed Mahdi Althaf (GMC 7216325).

Evidence-based by design

Plain-English test explanations and actionable next steps.

Designed by a UK Consultant Nephrologist

Ready to support your kidney health?

If you have been researching kidney health, supplements, CKD nutrition or kidney-friendly living, Kidney Vitality was developed specifically around those principles by Professor Mohammed Mahdi Althaf (GMC 7216325). Developed using renal nutrition principles.

  • Designed Using Renal Nutrition Principles
  • No Added Potassium
  • No Added Phosphorus
  • UK Manufactured
  • One capsule daily
  • UK GMP — BRCGS, NSF GMP, Halal
Subscribe & Save — £20.39/monthCheck your current multivitamin

✓ Free UK tracked delivery  ·  ✓ Delivered every 30 days  ·  ✓ Pause or cancel anytime  ·  ✓ Never run out

ComparisonKidney VitalityTypical high-street multivitamin
Added potassiumNoneOften included
Added phosphateNoneOften included (E338–E452)
Vitamin A (retinol)No megadoseOften high-dose retinol
Kidney-focused formulationYesNo — general population
Consultant Nephrologist involvementYes (GMC 7216325)No
UK GMP manufacturedYes (BRCGS, NSF GMP)Varies

Food supplement. Not a medicine and not a treatment for kidney disease. Speak with your GP, pharmacist or renal team before starting any new supplement, especially in advanced CKD, on dialysis, post-transplant, pregnant or breastfeeding.

Clinical reviewer

Professor Mohammed Mahdi Althaf

Consultant Nephrologist

Acute Physician

GMC 7216325

View Full Biography

Professor Mohammed Mahdi Althaf is a UK Consultant Nephrologist and Acute Physician with a special interest in chronic kidney disease, AKI prevention and renal nutrition. He combines hospital practice with patient education and clinical guidance review.

View professional profile →
View Credentials
  • MD
  • MSc
  • PgDip (Clin Ed)
  • FRCP
  • FHEA
  • FASN

About this article

Written for UK patients and based on:

  • NICE guidance
  • NHS resources
  • British Dietetic Association guidance
  • Kidney Care UK resources
View methodology

Each article is researched against current UK clinical guidance (NICE NG203, NG118, NG136), NHS patient resources, KDIGO and KDOQI international guidelines, and the British Dietetic Association Renal Nutrition Group. Drafts are written by the Kidney Vitality editorial team and reviewed by a UK Consultant Nephrologist before publication. Content is reviewed on a rolling basis and updated when guidance changes.

Editorial standards

  • Clinically reviewed
  • NHS-aligned
  • NICE-aligned
  • Evidence-based
  • Reviewed before publication
View full editorial process

Every article is researched and written by the Kidney Vitality editorial team using current UK clinical guidance (NICE NG203, NG118, NG136), NHS patient resources, KDIGO/KDOQI international guidelines, and British Dietetic Association renal nutrition guidance. Drafts are reviewed for clinical accuracy by Professor Mohammed Mahdi Althaf, MD, MSc, PgDip (Clin Ed), FRCP, FHEA, FASN (Consultant Nephrologist & Acute Physician, GMC 7216325) before publication. Content is updated when UK guidance changes.

References (4)View Sources
  1. NICE NG203: Chronic kidney disease — assessment and management
  2. KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of CKD
  3. KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update
  4. British Dietetic Association — Renal Nutrition Group

Medical disclaimer

This content is educational only and does not replace personalised medical advice.

Read full disclaimer

This page is general information, not personal medical advice. If you have chronic kidney disease, are on dialysis, have had a kidney transplant, are pregnant or breastfeeding, or take prescription medication, please confirm any supplement with your GP, pharmacist or renal team before starting.

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