Creatinine
Waste product filtered by kidneys
21 of 22 providers
Kidney Function
Men:0.74-1.35 mg/dL, Women:0.59-1.04 mg/dL
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
Optimal vs Standard Ranges
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)
Scientific Evidence
Creatinine Limitations in Early CKD Detection
Serum creatinine remains normal until kidney function declines by 50% or more, making it insensitive for early CKD detection. Small changes in creatinine reflect large changes in GFR, especially at low baseline levels. A rise from 0.8 to 1.2 mg/dL represents ~40% GFR loss. eGFR equations (using creatinine, age, sex, race) improve accuracy but still miss early kidney disease. Cystatin C or direct GFR measurement may be needed in some cases.
ACE Inhibitors and ARBs Slow CKD Progression
ACE inhibitors and ARBs reduce proteinuria and slow progression of CKD, especially in diabetic nephropathy. They may cause initial creatinine increase of 10-20% (acceptable unless rise exceeds 30%). Long-term use reduces risk of kidney failure by 20-30% and cardiovascular events by similar magnitude. Benefits outweigh initial creatinine rise in most patients.
SGLT2 Inhibitors for Kidney Protection
SGLT2 inhibitors (empagliflozin, dapagliflozin, canagliflozin) slow CKD progression in diabetics and non-diabetics. The DAPA-CKD and EMPA-KIDNEY trials showed 30-40% reduction in kidney failure, cardiovascular death, or eGFR decline. Benefits persist even in advanced CKD (eGFR as low as 20-25 mL/min). Now recommended as standard therapy for CKD with proteinuria.
Source:Heerspink HJL, et al. Dapagliflozin in patients with chronic kidney disease. N Engl J Med. 2020;383(15):1436-1446.
Protein Restriction in Advanced CKD
Low-protein diets (0.6-0.8 g/kg/day) in patients with eGFR <60 mL/min reduce uremic toxin accumulation, slow GFR decline, and may delay need for dialysis by months to years. However, overly restrictive protein (<0.6 g/kg) risks malnutrition. Requires dietitian supervision and adequate calorie intake. Benefits most pronounced in Stage 4-5 CKD.
Source:Fouque D, et al. Low protein diets for chronic kidney disease in non diabetic adults. Cochrane Database Syst Rev. 2009;(3):CD001892.
Acute Kidney Injury and Long-term Risk
Even a single episode of AKI increases risk of developing CKD by 3-10 fold and accelerates progression in those with existing CKD. Approximately 25% of patients who recover from AKI develop CKD within 1-3 years. This highlights importance of AKI prevention, prompt treatment, and long-term follow-up of creatinine and eGFR after any AKI episode.
Source:Coca SG, et al. Chronic kidney disease after acute kidney injury:a systematic review and meta-analysis. Kidney Int. 2012;81(5):442-448.
Which Providers Test Creatinine?
Full Provider Comparison
| Provider | Includes | Annual Cost | Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ (150 with ratios) |
 WHOOP Advanced Labs | ✓ | $349 | 65 |
 Labcorp OnDemand | ✓ | $398 | 30+ |
| ✓ | $486 | 40+ | |
| ✓ | $444 | 288 | |
| ✓ | $349 | 100+ | |
| ✓ | $761 | 54 | |
 Function Health | ✓ | $365 | 160+ |
| ✓ | $250 | 65 | |
| ✓ | $495 | 70+ | |
| ✓ | $895 | 100+ | |
| ✓ | $1950 | 150+ | |
| ✓ | $375 | 80+ | |
| — | $Varies | 75+ | |
| ✓ | $190 | 100+ | |
| ✓ | $99 | 50 | |
| ✓ | $124 | 60 | |
| ✓ | $199 | 50 | |
| ✓ | $499 | 120+ | |
| ✓ | $4188 | 70-80+ | |
| ✓ | $375 | 85 | |
| ✓ | $700 | 128 |
Frequently Asked Questions
What is Creatinine?
Waste product filtered by kidneys
What is the optimal range for Creatinine?
The standard reference range for Creatinine is Men:0.74-1.35 mg/dL, Women:0.59-1.04 mg/dL. Optimal ranges may differ based on individual health goals and expert recommendations.
Which blood test providers include Creatinine?
21 out of 22 blood testing providers include Creatinine in their panels. This biomarker is widely available across major providers.
What category does Creatinine fall under?
Creatinine is categorized under Kidney Function. This category includes biomarkers that help assess related aspects of health and wellness.
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:2026-02-20