Clinician Guides 7 min read·Updated 16 July 2026 Clinician-reviewed

Creatinine Blood Test Results Explained

A UK Consultant Nephrologist-led plain-English guide to your serum creatinine result — what it is, what affects it, and how supplements can skew the number.

  • Clinically Reviewed
  • NHS & NICE Aligned
  • UK Evidence-Based
  • Last Reviewed 16 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

Creatinine is a muscle waste product filtered by the kidneys. Typical UK ranges: ~60–110 µmol/L (men), ~45–90 µmol/L (women). Dehydration, high-protein meals, hard exercise and creatine supplements can raise it without real kidney damage. Pause creatine 1–2 weeks before testing.

Key recommendation: Creatinine reflects muscle mass as well as kidney function.

Quick answer

✓ Best choices

  • Vegetables, lower-potassium fruit and whole grains
  • Sensible portions of fish, eggs, chicken or tofu
  • Olive oil and unsalted nuts in small amounts

✓ Foods to limit

  • Added salt and ultra-processed foods
  • Phosphate additives in processed meats and ready meals
  • Sugary and energy drinks

Key takeaway

Creatinine is a muscle waste product filtered by the kidneys. Typical UK ranges: ~60–110 µmol/L (men), ~45–90 µmol/L (women). Dehydration, high-protein meals, hard exercise and creatine supplements can raise it without real kidney damage. Pause creatine 1–2 weeks before testing.

Who should be cautious

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

Why this matters in chronic kidney disease

In chronic kidney disease (CKD), the kidneys gradually lose their ability to filter waste, balance electrolytes and clear excess nutrients. That means substances which are completely safe at typical doses in a healthy adult — including some vitamins and minerals — can build up or place added strain on the kidneys as function declines.

That's why UK renal nutrition guidance from NICE (NG203), KDOQI 2020 and the British Dietetic Association Renal Nutrition Group all take a cautious, individualised view of supplementation in CKD. The aim is to support overall nutrition without adding to the kidneys' workload.

Putting this into practice

If you're choosing a daily supplement and you have reduced kidney function, the most practical checks are simple: read the label, look at the doses, and look for what isn't added. Renal teams typically flag high-dose vitamin A (retinol), large doses of vitamin C, and any added potassium, phosphate or magnesium — these are the four ingredients most often singled out in routine dietetic reviews.

A evidence-based daily supplement keeps doses moderate, names the things it deliberately leaves out, and is formulated with renal nutrition in mind from the start — not adapted after the fact.

What to discuss with your renal team

Before starting any new vitamin or supplement, share the full label with your GP, renal pharmacist, dietitian or nephrologist. They will already know your blood results, prescribed phosphate binders, vitamin D regime and any active medication interactions — and can confirm whether a evidence-based daily supplement is appropriate alongside your current plan.

If you are on dialysis, are pregnant, are breastfeeding, or have had a kidney transplant, this conversation matters even more. The guidance on this page is general education, not a substitute for personalised clinical advice.

Vitamins for CKD Stage 3
Related reading: Vitamins for CKD Stage 3.

Key practical tips

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

  • Cook from scratch when you can
  • Read sodium labels (≤ 0.3 g per 100 g is low)
  • Take any concerns to your GP or renal team early

Clinical guidance

TL;DR summary

Creatinine is a muscle waste product filtered by the kidneys. Typical UK ranges: ~60–110 µmol/L (men), ~45–90 µmol/L (women). Dehydration, high-protein meals, hard exercise and creatine supplements can raise it without real kidney damage. Pause creatine 1–2 weeks before testing.

Key takeaways
  • Creatinine reflects muscle mass as well as kidney function.
  • Muscular people naturally sit at the higher end of normal.
  • Creatine monohydrate can raise creatinine artificially.
  • Pause creatine 1–2 weeks before kidney blood tests.
  • Kidney Vitality contains no creatine and no megadose protein.
Kidney Diet & Nutrition Considerations

Diet is one of the most powerful tools you have to look after your kidneys. UK renal guidance points to a Mediterranean-style, reduced-salt pattern: plenty of vegetables, lower-potassium fruit, whole grains, sensible protein, beans and pulses in moderation, oily fish and olive oil. Personal targets — for potassium, phosphate, protein and fluid — should be set by your renal team based on your bloods.

Foods to prioritise

  • Vegetables, lower-potassium fruit and whole grains
  • Sensible portions of fish, eggs, chicken or tofu
  • Olive oil and unsalted nuts in small amounts

Foods to limit

  • Added salt and ultra-processed foods
  • Phosphate additives in processed meats and ready meals
  • Sugary and energy drinks

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 is serum creatinine?

Creatinine is a waste product produced by muscle activity at a roughly constant rate. Healthy kidneys filter it out into the urine, so the level in the blood reflects kidney filtering capacity. It is the basis of the eGFR calculation.

What is a normal creatinine level?

Typical UK reference ranges are roughly 60–110 µmol/L for adult men and 45–90 µmol/L for adult women, but ranges vary by lab. Muscular people sit at the higher end; smaller people sit lower.

What can raise creatinine without true kidney damage?

Dehydration, very high-protein meals before the test, intense exercise in the previous 24–48 hours, creatine monohydrate supplements, and certain medicines (e.g. trimethoprim, cimetidine) can raise creatinine without truly reducing kidney function.

What can lower creatinine?

Low muscle mass, pregnancy, very low-protein diets and significant weight loss can lower creatinine. This means eGFR may overestimate kidney function in people with low muscle mass.

Should I stop creatine supplements before blood tests?

Yes — most renal teams suggest pausing creatine monohydrate for 1–2 weeks before kidney blood tests so the result reflects your true kidney function. Tell your GP about all supplements before testing.

Does Kidney Vitality affect creatinine?

Kidney Vitality does not contain creatine or megadose protein and is not expected to alter creatinine results. It is designed as evidence-based daily nutritional support, not a performance supplement.

What foods are good for kidney health?

A Mediterranean-style, mostly plant-based, reduced-salt diet is the most consistent evidence-based pattern for kidney health. Build meals around vegetables, lower-potassium fruit, whole grains, fish, eggs or tofu, beans and pulses in moderation, and olive oil.

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

Written by a UK Consultant Nephrologist

Professor Mohammed Mahdi Althaf (GMC 7216325) leads our clinical content.

Supplement-aware

We explain how common supplements can affect kidney blood tests.

Plain-English explanations

No jargon — designed to help patients understand their own results.

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). Nephrologist Developed Daily Multivitamin.

  • No Added Potassium
  • No Added Phosphorus
  • No Added Iron
  • 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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