---
title: "Creatinine test: what it measures, normal levels, what a high creatinine means, and creatine vs creatinine"
type: biomarker
url: "https://www.test-well.com/biomarkers/creatinine"
also_known_as:
  - creatinine
  - creatinine, serum
category: Metabolic Health
units:
  - mg/dL
order_price_usd: 20.99
order_item: Basic Metabolic Panel
order_url: "https://www.test-well.com/tests/basic-metabolic-panel"
reviewed_at: 2026-09-20
---

# Creatinine test: what it measures, normal levels, what a high creatinine means, and creatine vs creatinine

> Creatinine is measured with a standard blood draw after an 8–12 hour fast. A typical reference range is 0.740 – 1.35 mg/dL (male, age 18+; more bands below). At TestWell it's $20.99 all-in as Basic Metabolic Panel, results in 1–3 business days, drawn at Quest or Labcorp. An out-of-range result is a prompt to look closer, not a diagnosis.

Creatinine is a waste product your muscles make at a steady rate and your kidneys filter out of the blood. Because production is constant, the level in blood is a mirror of how well the kidneys are filtering: it climbs when filtration falls. Adults typically run about 0.74 to 1.35 mg/dL (men) and 0.59 to 1.04 mg/dL (women), and the lab converts the result into an eGFR that puts kidney function on a 0-to-100-plus scale.

Also known as: creatinine, creatinine, serum.

## Key facts

| Fact | Value |
| --- | --- |
| Units | mg/dL |
| Sample | Blood draw |
| Fasting | 8–12 hours |
| Results | 1–3 business days |
| Price | $20.99 |
| Labs | Quest or Labcorp · BioReference in NY/NJ |

## What does a creatinine test measure?

Every time a muscle contracts it burns creatine phosphate for energy, and a small, predictable fraction of that creatine breaks down into creatinine. The amount produced each day depends mainly on how much muscle you carry, which is why a large, muscular man runs higher than a small woman and why levels are so steady from week to week in the same person. Creatinine has no job in the body; it is simply a waste product that drifts into the blood and has to be removed.

The kidneys do the removing. Blood passes through roughly a million filtering units in each kidney, the glomeruli, which let creatinine through into the urine while holding back cells and proteins. A little more is actively pushed into the urine by the kidney tubules. Because production is constant and clearance is almost entirely by filtration, the concentration left in blood is a direct read on filtering capacity: when filtration halves, creatinine roughly doubles.

A serum creatinine test measures that concentration in milligrams per deciliter (mg/dL). It is included in the basic and comprehensive metabolic panels, the kidney or renal panel, and most routine blood work, so most people have had one without asking for it. On its own the number is only half the story; the lab uses it to calculate eGFR, described below, and clinicians read it alongside BUN and, increasingly, cystatin C.

## Who should get a creatinine test?

Chronic kidney disease causes no symptoms until it is advanced, so the people who most need a creatinine test are the ones at risk rather than the ones who feel unwell. The National Kidney Foundation and the American Diabetes Association recommend at least yearly testing for anyone with diabetes or high blood pressure, the two conditions behind most kidney disease in the United States. Cardiovascular disease, a family history of kidney failure, obesity, and age over 60 are the other common reasons to check regularly.

Medications are a second large group. Non-steroidal anti-inflammatory drugs taken daily, lithium, certain antibiotics and antivirals, some chemotherapy agents and the contrast dye used in CT scans can all injure the kidneys, and a baseline creatinine before starting them, then periodic checks, is standard practice. Metformin, several blood-pressure medicines and many other drugs are dosed according to kidney function, so the result also changes how other prescriptions are written.

People on GLP-1 medicines, testosterone therapy or peptide protocols usually have creatinine on their monitoring panel, and anyone who takes creatine or eats a very high-protein diet should know their baseline, because both raise creatinine without harming the kidneys, as explained in the creatine vs creatinine section. Symptoms that do warrant a test rather than a routine check include swelling of the ankles or around the eyes, foamy urine, urinating far more or less than usual, persistent fatigue with nausea, and muscle cramps or itching that has no other explanation.

## How to get a creatinine test and prepare for it

Creatinine is rarely ordered alone. The usual routes are a basic metabolic panel, which adds glucose, electrolytes and BUN; a comprehensive metabolic panel, which adds liver markers and proteins as well; or a dedicated kidney panel that pairs it with BUN, electrolytes and eGFR. You can have any of these ordered by your doctor, or order one online from TestWell and have blood drawn at a Quest or Labcorp patient service center, with a licensed physician reviewing the order and results in your portal within a few business days.

Preparation is simple but matters more than people expect. Arrive normally hydrated; dehydration concentrates the blood and can push creatinine above the reference range in a person with healthy kidneys. Skip strenuous exercise for 24 to 48 hours, because muscle breakdown after a hard workout releases extra creatinine. Avoid a large meal of cooked meat the evening before or the morning of the draw, since cooking converts the creatine in meat into creatinine that is absorbed directly into the blood. Fasting is not required for creatinine itself, though the metabolic panels it travels in are often drawn fasting for the glucose result.

Tell the ordering physician about creatine supplements, trimethoprim or cimetidine (both block the tubular secretion of creatinine and raise the level without changing filtration), and any recent contrast scan. If a result is being compared with an earlier one, having it drawn at the same lab, at a similar time of day and under similar conditions removes most of the noise.

## What is the normal range for Creatinine?

| Population | Reference range |
| --- | --- |
| Male, age 18+ | 0.740 – 1.35 mg/dL |
| Female, age 18+ | 0.590 – 1.04 mg/dL |

Reference intervals differ slightly between labs; the range printed on your report is the one to interpret against. Ranges are usually set so 95% of healthy people fall inside them.

## Normal creatinine levels and how eGFR is calculated

Reference ranges differ by sex because they differ by muscle mass. Mayo Clinic Laboratories reports 0.74 to 1.35 mg/dL for adult men and 0.59 to 1.04 mg/dL for adult women; other laboratories publish ranges within a few hundredths of these, and the report you receive will show the range for the lab that ran the sample. Children run lower, older adults with less muscle run lower for the same kidney function, and a very muscular adult can sit slightly above the range with perfectly healthy kidneys.

Because the same creatinine value means different things in a 25-year-old bodybuilder and an 80-year-old woman, laboratories convert it into an estimated glomerular filtration rate. The equation in use across the United States since 2021, CKD-EPI 2021, combines creatinine with age and sex and no longer includes a race term. The result is expressed in mL/min/1.73 m², where anything at or above 90 is normal filtration, 60 to 89 is mildly reduced (which is common and usually insignificant in older adults without other signs of kidney damage), 45 to 59 is mildly to moderately reduced, 30 to 44 moderately to severely reduced, 15 to 29 severely reduced, and below 15 is kidney failure.

One limitation is important to understand: creatinine is a late marker. Filtration can fall by close to half before creatinine leaves the reference range, which is why an eGFR of 65 with a creatinine that still reads normal is worth attention, and why clinicians pair the blood test with a urine albumin-to-creatinine ratio. Albumin leaking into urine (30 mg/g or more) often shows kidney damage years before eGFR falls.

| eGFR (mL/min/1.73 m²) | KDIGO category | What it usually means |
| --- | --- | --- |
| 90 or higher | G1 — normal or high | Normal filtration; kidney disease only if there is another sign of damage such as albumin in the urine |
| 60–89 | G2 — mildly decreased | Common with age; not chronic kidney disease unless there is also albuminuria or another marker of damage |
| 45–59 | G3a — mild to moderate decrease | Chronic kidney disease if it persists 3 months; medication review and yearly monitoring |
| 30–44 | G3b — moderate to severe decrease | Closer monitoring, nephrology referral is common, blood pressure and diabetes control become central |
| 15–29 | G4 — severely decreased | Nephrology care; planning for kidney replacement therapy begins |
| Below 15 | G5 — kidney failure | Dialysis or transplant evaluation |

_KDIGO 2024 GFR categories. Chronic kidney disease is defined as GFR below 60 or a marker of kidney damage persisting for more than 3 months._

## High creatinine: what it usually means

The common causes come first. In someone with no kidney history, a mildly high creatinine is most often explained by dehydration, a heavy workout in the previous day or two, a large meat meal, creatine supplementation or simply a lot of muscle. Repeating the test under standard conditions, well hydrated and rested, resolves many of these on its own. A creatinine that stays high on a repeat draw is where the kidney work-up begins.

Reduced kidney filtration is the cause that matters. Long-standing diabetes and high blood pressure account for most cases and damage the kidneys slowly, so the creatinine creeps up over years. Faster rises come from acute kidney injury: severe dehydration or blood loss, sepsis, a blockage in urine flow from an enlarged prostate or kidney stones, and drugs including NSAIDs, contrast dye and some antibiotics. Glomerular diseases such as lupus nephritis and IgA nephropathy, polycystic kidney disease and rhabdomyolysis (massive muscle breakdown, which floods the blood with creatinine and can itself injure the kidney) are less common but important causes.

Two things separate a kidney cause from a muscle or medication cause. The first is eGFR read together with cystatin C: cystatin C is produced by all cells rather than by muscle, so an eGFR calculated from cystatin C that agrees with the creatinine-based one confirms a filtration problem, while a normal cystatin C eGFR points back to muscle mass, diet or a secretion-blocking drug. The second is the urine: albumin, blood or protein in the urine indicates kidney damage, whereas a clean urinalysis with a high creatinine in a muscular person on creatine is reassuring.

## Low creatinine: usually about muscle, not kidneys

A low creatinine almost never signals a kidney problem, because kidneys that filter well simply keep the level at the low end of normal. Instead it reflects low production: small body size, low muscle mass from age, inactivity or prolonged illness, an amputation, malnutrition or a very low-protein or vegan diet, and advanced liver disease, where less creatine is made in the first place. Pregnancy lowers creatinine too, because filtration rises by about half in the second trimester and dilutes the blood.

The practical consequence of a low creatinine is not the value itself but what it does to eGFR. Because the equation assumes average muscle mass, a frail or sarcopenic person can have a reassuring eGFR while true filtration is considerably lower. KDIGO recommends adding cystatin C in exactly this situation, and dosing decisions for kidney-cleared drugs in older or very thin patients often rely on it.

## Creatine vs creatinine

Creatine is a nutrient; creatinine is its waste product. Creatine is made by the liver and kidneys from amino acids, obtained from meat and fish, and stored in muscle as creatine phosphate, where it regenerates ATP during short bursts of effort. That is why creatine monohydrate is the most studied sports supplement. Creatinine is what creatine becomes when it is used and broken down, and it is measured only because it happens to be a convenient marker of kidney filtration.

Taking creatine raises creatinine. Loading doses can lift serum creatinine by roughly 0.1 to 0.3 mg/dL, sometimes enough to move a result just above the reference range and lower the calculated eGFR by several points, even though the kidneys are filtering normally. Multiple controlled trials in healthy adults have found no evidence that creatine at standard doses damages the kidneys; the elevated creatinine is a production artifact, not a filtration failure. The same is true of a diet very high in cooked meat.

If you supplement, tell the ordering clinician and either pause creatine for about a week before a baseline test or ask for cystatin C alongside creatinine, which is unaffected by supplementation and settles the question. A high creatinine in a creatine user with a normal cystatin C eGFR and a clean urinalysis is a supplement effect, not kidney disease.

## What happens after an abnormal creatinine result

A single high creatinine is repeated before anything is concluded, typically within a few weeks and under standard conditions: normal hydration, no hard training for two days, no large meat meal, creatine paused if practical. A repeat in range with a normal eGFR closes the question for most people. A repeat that is still high leads to the standard kidney work-up: a urine albumin-to-creatinine ratio, a urinalysis, cystatin C if muscle mass or medications could be confounding the picture, and a review of every medication and supplement for anything that raises creatinine or injures the kidney.

Chronic kidney disease is diagnosed only when reduced eGFR or a marker of damage persists for more than 3 months, so the timeline is measured in months, not days, unless the rise is steep or accompanied by symptoms. When it is confirmed, the priorities that slow it down are well established: blood pressure control, glucose control in diabetes, avoiding NSAIDs and other nephrotoxins, and medicines such as SGLT2 inhibitors that protect the kidney, prescribed and adjusted by the treating clinician. Symptoms such as rapidly worsening swelling, very little urine, confusion or shortness of breath alongside a high creatinine need same-day medical care.

## What does a high Creatinine mean?

Creatinine is a waste product cleared by the kidneys; a high level means the kidneys are filtering less — or that there is more muscle producing it. Dehydration, high meat intake, creatine supplements, intense exercise and certain medications (NSAIDs, some blood-pressure drugs, trimethoprim) raise it transiently. eGFR translates creatinine into kidney function; a persistent eGFR under 60 for three months defines chronic kidney disease.

### Common causes of high Creatinine

1. Dehydration
2. Acute or chronic kidney disease (diabetes and high blood pressure are the leading causes)
3. High muscle mass, creatine supplements, large meat meals, intense exercise
4. Medications: NSAIDs, ACE inhibitors/ARBs (small rise expected), trimethoprim, cimetidine, some antibiotics
5. Urinary obstruction (enlarged prostate, stones)

### Symptoms that go with high Creatinine

- Usually none until kidney function is significantly reduced
- Swelling, fatigue, reduced urine output, nausea when advanced

### What clinicians usually check next

- Repeat well-hydrated, without creatine or heavy exercise for 48 hours
- Urine albumin-to-creatinine ratio and urinalysis
- Cystatin C–based eGFR when muscle mass could be skewing creatinine
- Blood pressure and A1c review; kidney ultrasound if persistently reduced

### Seek care promptly if

- A sharp rise in creatinine with very little urine, swelling or breathlessness — same-day care

**Can creatine supplements raise creatinine?** Yes — creatine breaks down to creatinine, so users often read slightly high without any kidney problem. Stop for a few days and repeat, or ask for a cystatin C.

## What does a low Creatinine mean?

A low creatinine usually reflects low muscle mass — older age, small frame, prolonged illness or malnutrition — and occasionally pregnancy (higher filtration), liver disease or a very low-protein diet. It is rarely a kidney problem in itself; it does make creatinine-based eGFR overestimate kidney function, which is where cystatin C helps.

### Common causes of low Creatinine

1. Low muscle mass: older adults, small body size, muscle-wasting conditions
2. Pregnancy
3. Liver disease, malnutrition, vegetarian diets
4. Overhydration (dilution)

### Symptoms that go with low Creatinine

- None from the creatinine itself

### What clinicians usually check next

- Usually none; consider cystatin C if accurate kidney function matters
- Nutrition and muscle assessment if unexpected

**Is low creatinine dangerous?** No. It's a marker of low muscle mass rather than disease, though it can make kidney function look better than it is.

## How do you get tested for Creatinine?

| Order | Type | Price | Includes |
| --- | --- | --- | --- |
| [Basic Metabolic Panel](https://www.test-well.com/tests/basic-metabolic-panel) | Single test | $20.99 | This marker |

## Quest vs Labcorp vs BioReference

| Lab | Available | Price | Notes |
| --- | --- | --- | --- |
| Quest Diagnostics | Yes | $20.99 | Choose Quest at checkout; walk-in patient service centers in every state TestWell serves outside NY and NJ. |
| Labcorp | Yes | $21.99 | Choose Labcorp at checkout; walk-in patient service centers in every state TestWell serves outside NY and NJ. |
| BioReference (NY & NJ) | Yes | $22.99 | New York and New Jersey orders route here automatically — state rules keep Quest and Labcorp from accepting self-ordered draws. |

## Common questions about Creatinine

### What is a normal creatinine level?

Roughly 0.74 to 1.35 mg/dL for adult men and 0.59 to 1.04 mg/dL for adult women, using the Mayo Clinic Laboratories ranges; your report shows the range for the lab that ran the test. Men run higher because they carry more muscle. The number is interpreted through eGFR, where 90 or above is normal filtration.

### What is the difference between creatinine and eGFR?

Creatinine is the measured concentration of the waste product in blood. eGFR is calculated from that creatinine together with your age and sex (CKD-EPI 2021) to estimate how many milliliters of blood your kidneys filter per minute. eGFR is the number kidney disease is staged on; creatinine is the raw ingredient.

### Does creatine raise creatinine?

Yes. Creatine supplements increase creatinine production and can raise the blood level by about 0.1 to 0.3 mg/dL, lowering calculated eGFR without any change in real kidney filtration. Controlled studies have not found kidney damage from standard doses. Pause creatine for about a week before testing, or ask for cystatin C, to get a clean read.

### Do I need to fast for a creatinine test?

Not for creatinine itself. The basic and comprehensive metabolic panels it is usually part of are often drawn fasting because they include glucose. What matters more for creatinine is arriving hydrated, skipping heavy exercise for a day or two and avoiding a large cooked-meat meal beforehand.

### What is a dangerous creatinine level?

There is no single cutoff, because the same value means different things at different ages and muscle masses. A creatinine that puts eGFR below 30, a level that has doubled from a previous result, or a high result with very little urine, swelling, confusion or shortness of breath all need prompt medical attention.

### Do I need a doctor's order to test my creatinine?

No. TestWell's licensed physician network reviews and approves your order — usually within minutes. You can place an order online without an in-person visit or a referral from your own doctor.

### How long does it take to get Creatinine results?

Most Creatinine results are available in 1–3 business days after your specimen arrives at the lab. You'll get an email the moment your results are ready, with everything viewable in your TestWell portal.

### How much does a Creatinine test cost?

Our Basic Metabolic Panel starts at $20.99. That's the all-in price — no copays, no insurance hoops, no surprise bills. HSA and FSA cards are accepted.

### Do I need to fast before my Creatinine test?

Yes — for the most accurate result, fast for 8–12 hours before your blood draw. Water is fine; coffee, food, and supplements are not. Your prep instructions will be included with your order.

### Which lab will process my Creatinine test?

Your test will be processed by Quest Diagnostics, Labcorp, or BioReference depending on which is closest to you and which lab carries the test. All three are CLIA-certified and trusted by hospitals nationwide. You'll choose your lab during checkout from 4,000+ locations.

## Keep reading

- [CMP vs BMP: What's the Difference, and Which Metabolic Panel Do You Need?](https://www.test-well.com/guides/cmp-vs-bmp)
- [How to Read Your Blood Test Results](https://www.test-well.com/guides/how-to-read-your-blood-test-results)
- [Metabolic Lab Testing: Which Panel Do You Actually Need?](https://www.test-well.com/guides/metabolic-lab-testing)
- [GLP-1 Lab Monitoring: Bloodwork for Ozempic, Wegovy, Mounjaro & Zepbound](https://www.test-well.com/guides/glp1-lab-monitoring)
- [Fatigue: which blood tests?](https://www.test-well.com/symptoms/fatigue)
- [Swollen ankles and legs: which blood tests?](https://www.test-well.com/symptoms/swollen-ankles)
- [Frequent urination: which blood tests?](https://www.test-well.com/symptoms/frequent-urination)
- [Nausea: which blood tests?](https://www.test-well.com/symptoms/nausea)
- [Muscle cramps: which blood tests?](https://www.test-well.com/symptoms/muscle-cramps)
- [Itchy skin without a rash: which blood tests?](https://www.test-well.com/symptoms/itchy-skin)
- [Before your test: Hydration](https://www.test-well.com/prep/hydration)
- [Before your test: Exercise](https://www.test-well.com/prep/exercise)
- [Before your test: Creatine supplements](https://www.test-well.com/prep/creatine-supplements)
- [Before your test: Keto and high-protein diets](https://www.test-well.com/prep/keto-and-high-protein-diets)
- [Before your test: Common medications](https://www.test-well.com/prep/medications)
- [Before your test: Fasting](https://www.test-well.com/prep/fasting)

## Sources

- [Mayo Clinic Labs](https://www.mayocliniclabs.com/test-catalog/overview/8472)
- [MedlinePlus (NIH) — Creatinine Test](https://medlineplus.gov/lab-tests/creatinine-test/)
- [National Kidney Foundation — CKD-EPI Creatinine Equation (2021)](https://www.kidney.org/professionals/kdoqi/gfr_calculator)
- [KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease](https://kdigo.org/guidelines/ckd-evaluation-and-management/)
- [NIDDK (NIH) — Chronic Kidney Disease Tests & Diagnosis](https://www.niddk.nih.gov/health-information/kidney-disease/chronic-kidney-disease-ckd/tests-diagnosis)
- [International Society of Sports Nutrition — Position Stand: Safety and Efficacy of Creatine Supplementation (2017)](https://doi.org/10.1186/s12970-017-0173-z)

## Related biomarkers

- [Glucose](https://www.test-well.com/biomarkers/glucose)
- [eGFR](https://www.test-well.com/biomarkers/egfr)
- [BUN](https://www.test-well.com/biomarkers/bun)
- [ALT](https://www.test-well.com/biomarkers/alt)
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- [Reference range lookup tool](https://www.test-well.com/tools/reference-range-lookup)
- [Lab unit converter](https://www.test-well.com/tools/lab-unit-converter)
- [All biomarkers](https://www.test-well.com/biomarkers)

---

Medically reviewed by Youmna DiStefano, MD (Medical Reviewer, TestWell); last reviewed 2026-09-20. Review policy: https://www.test-well.com/reviewers/youmna-distefano-md

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