Creatinine
Creatinine is a waste product from muscle breakdown of creatine phosphate that is cleared almost entirely by glomerular filtration. It is the standard marker of kidney filtration and is used with age, sex, and race to estimate GFR. Levels rise with acute or chronic kidney disease, dehydration, and high muscle mass, and fall with low muscle mass or liver disease.
Units: mg/dL; some labs report µmol/L (µmol/L = mg/dL × 88.4). Check the units on your report before comparing to any range here.
Optimal range: who says what
Institutions, researchers and practitioners draw the line in different places. Each position is listed with who holds it and, where a document states it, a link. How we verify ranges.
- Institution or study0.63-1.16 mg/dL (men)Age/sex reference intervals (Pottel et al. 2008, Clin Chim Acta)Reference interval, not an optimal target; stable from age 20 to 70 with a mean of 0.90 mg/dL. Muscle mass moves creatinine, so kidney function is judged by eGFR
- Institution or study0.48-0.93 mg/dL (women)Age/sex reference intervals (Pottel et al. 2008, Clin Chim Acta)Reference interval, not an optimal target; stable from age 20 to 70 with a mean of 0.70 mg/dL. Muscle mass moves creatinine, so kidney function is judged by eGFR
- Lab reference intervalMen: 0.74-1.35 mg/dL, Women: 0.59-1.04 mg/dLWhat a lab report flags against. A lab interval is not an optimal target.
21 of 21 itemized panels
Kidney Function
What is Creatinine?
Creatinine is a waste product produced by your muscles from the breakdown of creatine phosphate, a molecule that stores energy for muscle contraction. Your body produces creatinine at a relatively constant rate based on your muscle mass—typically 1-2 grams per day. This waste product is filtered out of your blood by your kidneys and excreted in urine.
Because creatinine production is steady and it is freely filtered by the kidneys without being reabsorbed, serum creatinine is an excellent marker of kidney filtration function. When kidney function declines, creatinine accumulates in the blood and serum levels rise. However, creatinine is not perfect: it is affected by muscle mass, age, sex, diet (cooked meat intake), and certain medications.
Creatinine is used to calculate eGFR (estimated glomerular filtration rate), which provides a more accurate assessment of kidney function than creatinine alone. Because muscular individuals naturally have higher creatinine, and elderly or frail individuals have lower creatinine, the absolute value must be interpreted in context. Small changes in creatinine can represent significant changes in kidney function, especially at lower baseline levels.
Why Creatinine Is Your Primary Kidney Function Marker
- Kidney function screening: Most widely used marker to detect reduced kidney filtration. Elevated creatinine indicates impaired kidney function
- eGFR calculation: Combined with age, sex, and race, creatinine is used to calculate eGFR, which stages chronic kidney disease
- Medication dosing: Many drugs are cleared by kidneys and require dose adjustment based on creatinine/eGFR
- Early detection limitation: Creatinine rises only after 50% or more kidney function is lost, so normal creatinine doesn't guarantee healthy kidneys
- Muscle mass indicator: Can reflect muscle wasting in chronic illness or sarcopenia in elderly (low creatinine)
- Acute kidney injury detection: Rapid rise in creatinine (>0.3 mg/dL in 48 hours) indicates acute kidney injury requiring urgent evaluation
Interpretation bands (curated, PMID-backed)
Holder: OptimizeBiomarkers editorial synthesis of: Chronic kidney disease and mortality risk: a systematic review (Tonelli et al., 2006); Renal impairment and outcomes in heart failure: systematic review and meta-analysis (Smith et al., 2006); Estimated glomerular filtration rate and albuminuria for prediction of cardiovascular outcomes: a collaborative meta-analysis of individual participant data (Matsushita et al., 2015). No single paper sets these cutoffs; for attributed targets see who says what.
OptimalMen: 0.8-1.2 mg/dL, Women: 0.6-1.0 mg/dL▼
- Indicates healthy kidney function with eGFR typically >90 mL/min/1.73m²
- Reflects good muscle mass and normal kidney filtration
- Athletes and muscular individuals may be at higher end of range or slightly above without indicating kidney disease
- Elderly and low muscle mass individuals may be at lower end
Borderline ElevatedMen: 1.2-1.5 mg/dL, Women: 1.0-1.3 mg/dL▼
- May indicate early kidney dysfunction (eGFR 60-90 mL/min) or high muscle mass
- Requires investigation with eGFR calculation and urinalysis
- Check for proteinuria, diabetes, hypertension
- Rule out dehydration, recent high protein meal, or strenuous exercise
- Retest in 3 months
- If eGFR 60-90 with no other abnormalities, may be normal for muscular individuals
Elevated (Stage 2-3 CKD)Men: 1.5-3.0 mg/dL, Women: 1.3-2.5 mg/dL▼
- Indicates moderate kidney dysfunction (eGFR 30-60 mL/min, Stage 2-3 CKD)
- Requires nephrology evaluation, investigation of underlying cause (diabetes, hypertension, glomerulonephritis), and management to slow progression
- Check urinalysis for protein/blood, kidney ultrasound
- Start ACE inhibitor or ARB if proteinuria present
- Monitor every 3-6 months
- Address cardiovascular risk factors aggressively
Severely Elevated (Stage 4-5 CKD)>3.0 mg/dL (men), >2.5 mg/dL (women)▼
- Indicates advanced kidney disease (eGFR <30 mL/min, Stage 4-5 CKD) or acute kidney injury
- Requires urgent nephrology referral
- eGFR <15 mL/min (Stage 5) requires dialysis or transplant planning
- Check for uremic symptoms (nausea, fatigue, confusion, pericarditis)
- Monitor electrolytes (potassium, phosphate), anemia, bone health
- Adjust all medication dosing
- Prepare for renal replacement therapy (dialysis or transplant)
- Chronic kidney disease and mortality risk: a systematic review.
- Renal impairment and outcomes in heart failure: systematic review and meta-analysis.
- Estimated glomerular filtration rate and albuminuria for prediction of cardiovascular outcomes: a collaborative meta-analysis of individual participant data.
What raises or lowers Creatinine
Causes of high Creatinine
- Chronic kidney disease: Diabetes (most common cause), hypertension, glomerulonephritis, polycystic kidney disease, chronic interstitial nephritis, prolonged obstruction
- Acute kidney injury: Dehydration/volume depletion (pre-renal), sepsis/shock, nephrotoxic drugs (NSAIDs, aminoglycosides, contrast dye), rhabdomyolysis (muscle breakdown), obstruction (kidney stones, enlarged prostate, tumors)
- Medications: NSAIDs, ACE inhibitors/ARBs (can increase creatinine), trimethoprim, cimetidine (interfere with creatinine secretion without true kidney dysfunction)
- High muscle mass: Athletes, bodybuilders naturally have higher creatinine without kidney disease
- High protein diet: Recent consumption of cooked meat (contains creatine/creatinine) can temporarily increase levels
- Dehydration: Concentrates creatinine and reduces kidney perfusion
- Rare: Gigantism, acromegaly (excess growth hormone)
Causes of low Creatinine
- Low muscle mass: Elderly, sarcopenia, cachexia, muscular dystrophy, prolonged immobilization
- Malnutrition: Inadequate protein intake, anorexia, malabsorption
- Chronic diseases: Advanced cancer, liver cirrhosis (reduced creatine synthesis), chronic heart failure
- Pregnancy: Increased GFR and blood volume lower creatinine
- Vegetarian/vegan diet: Lower creatine/creatinine production from meat-free diet
Symptoms when Creatinine is high or low
When high
- Early CKD (creatinine 1.5-2.5): Often asymptomatic; fatigue, mild nausea may occur
- Moderate to Advanced CKD (creatinine >2.5): Fatigue and weakness, poor appetite and weight loss, nausea and vomiting, metallic taste, sleep disturbances, decreased urine output or foamy urine (if proteinuria), swelling (legs, ankles, face)
- Severe CKD/Uremia (creatinine >5-8): Confusion and difficulty concentrating (uremic encephalopathy), shortness of breath (fluid overload, acidosis), itching (uremic pruritus), muscle cramps and restless legs, chest pain (pericarditis—medical emergency)
- Acute kidney injury: Rapid rise in creatinine with decreased urine output, confusion, nausea
Symptoms correlate more with eGFR than creatinine level. Two people with same creatinine may have different symptoms based on chronicity, rate of rise, and muscle mass. Uremic symptoms with creatinine >8-10 mg/dL indicate need for dialysis.
When low
Low creatinine rarely causes symptoms but may indicate:
- Muscle wasting (sarcopenia): Loss of muscle mass, weakness, frailty (common in elderly)
- Malnutrition: Inadequate protein intake or chronic illness
- Chronic diseases: Cancer, liver disease, muscular dystrophy
- Pregnancy: Dilutional effect and increased GFR lower creatinine
Very low creatinine (<0.5 mg/dL) warrants evaluation for muscle wasting, malnutrition, or chronic disease. Not typically dangerous itself but indicates underlying issues.
How to move Creatinine
Effect sizes (how much something moves the marker) appear only where the paper cited under the item states them. Talk to your clinician before starting or changing any medication or supplement.
Slow Progression of Chronic Kidney Disease
- ACE inhibitors or ARBs: First-line therapy if proteinuria or diabetes present. Reduce proteinuria and slow CKD progression. A small early rise in creatinine is expected and usually acceptable
- SGLT2 inhibitors: Empagliflozin, dapagliflozin slow CKD progression, especially in diabetics. Reduce cardiovascular events and kidney failure
- Blood pressure control: Treat to the blood pressure target your clinician sets. Lower BP slows kidney damage
- Glycemic control: If diabetic, keep HbA1c at the target your clinician sets. Poor glucose control accelerates kidney decline
- Treat underlying cause: Address glomerulonephritis, autoimmune disease, obstruction, or other reversible causes
Dietary Modifications for Kidney Health
- Moderate protein intake: If eGFR <60, limit to 0.6-0.8 g/kg daily to reduce kidney workload. Too low causes malnutrition; work with dietitian
- Reduce sodium: <2000-2300 mg daily. High sodium worsens hypertension and proteinuria
- Limit phosphate: If advanced CKD (eGFR <45), restrict phosphate-rich foods (dairy, processed foods, cola) to <800-1000 mg/day
- Potassium management: If hyperkalemia (K+ >5.0), limit high-potassium foods (bananas, oranges, potatoes, tomatoes)
- Adequate hydration: 2-3 liters daily unless fluid restriction needed (advanced CKD with fluid retention)
- Avoid nephrotoxins: NSAIDs (ibuprofen, naproxen), excessive protein supplements, herbal supplements (aristolochic acid)
Manage Complications of CKD
- Anemia treatment: If hemoglobin <10 g/dL, consider erythropoietin-stimulating agents (ESAs) and iron supplementation. Your nephrologist sets the hemoglobin target
- Bone health: CKD causes secondary hyperparathyroidism. Monitor calcium, phosphate, PTH, vitamin D. Supplement vitamin D, use phosphate binders if needed
- Metabolic acidosis: If bicarbonate <22 mEq/L, consider sodium bicarbonate supplementation to slow CKD progression
- Hyperkalemia management: Avoid potassium-rich foods, use potassium binders (patiromer, sodium zirconium cyclosilicate) if needed
- Cardiovascular protection: CKD greatly increases CV risk. Statin therapy, aspirin, intensive BP control reduce events
Address Acute Kidney Injury (if Rapid Rise)
- Identify cause: Pre-renal (dehydration, low blood pressure), renal (drug toxicity, contrast dye, glomerulonephritis), post-renal (obstruction from stones, enlarged prostate)
- Stop nephrotoxic medications: NSAIDs, aminoglycosides, vancomycin, contrast dye, ACE inhibitors (temporarily)
- Restore volume: IV fluids if dehydrated or hypotensive. Correct underlying shock or bleeding
- Relieve obstruction: Foley catheter if urinary retention, urology consultation if kidney stones or prostatic obstruction
- Monitor closely: Check creatinine daily until stable or improving. Watch for hyperkalemia, acidosis, volume overload
Optimize Muscle Mass (if Low Creatinine)
- Low creatinine (<0.6 mg/dL in men, <0.5 in women) may indicate sarcopenia or malnutrition rather than superior kidney function
- Resistance training: Weight training two to three times a week builds muscle, and creatinine rises with muscle mass
- Adequate protein: 1.2-1.6 g/kg daily, especially in elderly. Combine with exercise for muscle synthesis
- Creatine supplementation: 3-5g daily creatine monohydrate increases muscle creatine stores, strength, and muscle mass. Will increase creatinine slightly (normal)
- Address hormones: Low testosterone in men or growth hormone deficiency can cause muscle wasting. Consider evaluation if low creatinine with low muscle mass
When to retest
- Baseline: Healthy adults should check creatinine every 1-2 years as part of routine screening
- If borderline elevated: Retest in 3 months with eGFR, urinalysis. If stable and eGFR >60, may be normal variant
- If elevated with CKD: Stage 3 CKD (eGFR 30-60): Every 3-6 months. Stage 4-5 CKD (eGFR <30): Every 1-3 months
- After medication changes: If starting ACE inhibitor, ARB, or SGLT2 inhibitor, recheck in 1-2 weeks (a small rise is expected; a large one needs review). If starting nephrotoxic drugs, monitor closely
- During acute illness: If hospitalized or acutely ill, check daily until stable
- After acute kidney injury: Monitor every 3-7 days until creatinine returns to baseline, then follow up at 3 and 6 months (AKI raises the risk of later CKD)
- Diabetics and hypertensives: Annual creatinine/eGFR screening to detect early kidney disease
Scientific Evidence
Creatinine Overestimates Kidney Function
In 171 patients with glomerular disease, creatinine clearance averaged 1.64 times inulin clearance because damaged tubules secrete creatinine, and this secretion rose as filtration fell. Creatinine therefore overestimated GFR and blunted the apparent change as disease progressed.
Source: Limitations of creatinine as a filtration marker in glomerulopathic patients.
ARB Slows Diabetic Kidney Disease
In 1,715 hypertensive patients with kidney disease from type 2 diabetes, irbesartan lowered the risk of doubling creatinine, end-stage kidney disease or death by 20% versus placebo and 23% versus amlodipine, independent of blood pressure. Creatinine rose 24% more slowly than with placebo.
Which Providers Test Creatinine?
Cheapest: Oura Health Panels at $99/year. Most comprehensive: Function Health, 160+ biomarkers for $365/year.
21 panels that include it, cheapest first
| Provider | Annual Cost | Total Biomarkers | $/Biomarker |
|---|---|---|---|
| $99 | 50 | $1.98 | |
| $190 | 100+ | $1.90 | |
| $250 | 65 | $3.85 | |
| $297 | 100+ | $2.97 | |
 Labcorp OnDemand | $338 | 50+ | $6.76 |
 Superpower | $349 | 100+ | $3.49 |
| $349 | 75+ | $4.65 | |
 WHOOP Advanced Labs | $349 | 65 | $5.37 |
 Function Health | $365 | 160+ | $2.28 |
| $365 | 100+ | $3.65 | |
| $375 | 108 | $3.47 | |
| $449 | 83 | $5.41 | |
| $495 | 80+ | $6.19 | |
| $499 | 100+ | $4.99 | |
| $700 | 138 | $5.07 | |
| $829 | 54 | $15.35 | |
| $895 | 100+ | $8.95 | |
| $996 | 59 | $16.88 | |
| $1188 | 70+ | $16.97 | |
| $1198 | 40+ | $29.95 | |
| $1950 | 130+ | $15.00 |
$/Biomarker is annual cost divided by the panel's advertised biomarker count, not the price of this one test. We track 23 blood test providers (32 plans); 21 of those plans are itemized marker by marker. Compare all of them.
11 providers not itemized in our matrix
We have not itemized these marker by marker (some sell tests one at a time), so this page cannot say whether they offer Creatinine. Check with them directly.
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Experts discussing Creatinine
Podcast episodes where clinicians and researchers cover this marker in depth. Curated by hand; an episode is listed only when the marker is a substantial topic, not a passing mention.
Frequently Asked Questions
What is the optimal range for Creatinine?
Published positions differ: 0.63-1.16 mg/dL (men) (Age/sex reference intervals (Pottel et al. 2008, Clin Chim Acta)); 0.48-0.93 mg/dL (women) (Age/sex reference intervals (Pottel et al. 2008, Clin Chim Acta)). Lab reference interval: Men: 0.74-1.35 mg/dL, Women: 0.59-1.04 mg/dL. That is what a lab report flags against, not an optimal target.
Which blood test providers include Creatinine?
21 of the 21 blood testing panels we itemize marker by marker include Creatinine in their panels. This biomarker is widely available across major providers.
Related: YouBoost rates lifestyle and supplement interventions by evidence.
Medical Disclaimer
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
Last reviewed Sep 23, 2026 · First published Sep 30, 2025