Creatinine blood test: what it means
What it measures
The creatinine blood test measures the amount of creatinine in your blood. Creatinine is a normal waste product your body makes when you use your muscles and some muscle tissue breaks down; healthy kidneys filter it out of the blood and remove it in urine. Because creatinine is removed from the body almost entirely by the kidneys, its level in the blood is used as a general indicator of how well the kidneys are working. It may be measured on its own or as part of a routine metabolic panel.
Why it’s ordered
A clinician may order this test to check kidney health as part of a routine checkup, to help diagnose or monitor kidney disease, or to watch for side effects of certain medications on the kidneys. It may also be ordered when someone has possible symptoms of kidney disease (per MedlinePlus, these can include swelling, dry or itchy skin, fatigue, changes in how often you urinate, bloody or foamy urine, loss of appetite, muscle cramps, nausea, shortness of breath, trouble sleeping, and trouble concentrating), or for people at higher risk, such as those with diabetes, high blood pressure, heart disease, or a family history of kidney disease.
General reference range
These figures are general reference values only and are not a personal cutoff or diagnosis. MedlinePlus lists a general normal range of about 0.7 to 1.3 mg/dL (62 to 115 µmol/L) for men and about 0.5 to 0.95 mg/dL (44 to 84 µmol/L) for women, and notes that women often have lower levels because they typically have less muscle mass. What is "normal" for you depends on factors such as muscle mass, body size, diet, age, and activity level. MedlinePlus states that "Normal value ranges may vary slightly among different laboratories," and that some labs use different measurements or test different samples. The reference range printed on your own lab report — and how your clinician interprets it for your age, sex, and health — is what applies to you. A normal result also does not always rule out kidney problems, since levels can stay normal in early kidney disease.
If it’s high
This is a list of general possibilities, not a diagnosis or a complete list. A higher-than-normal creatinine level may be seen with kidney problems such as kidney damage or failure, kidney infection, reduced blood flow to the kidneys, or a blocked urinary tract, and can also be associated with conditions such as heart failure or diabetes. Importantly, MedlinePlus notes that a high level does not always mean a kidney problem — it may also be linked to dehydration, muscle disorders or muscle breakdown, intense exercise, a diet high in meat, or pregnancy-related conditions such as preeclampsia or eclampsia. Only a clinician can interpret what a high result means in your specific situation.
If it’s low
Low blood creatinine levels are less common. When reported, a lower-than-normal level may be associated with malnutrition, with conditions that reduce muscle mass (including muscle or nerve disorders), or with serious liver disease. These are general possible associations, hedged and incomplete — not a diagnosis. A clinician interprets a low result in the context of your overall health.
A result is not a diagnosis
Reference ranges vary by laboratory, age, sex, and method — the range on your own report is what applies to you. A single value out of range doesn’t confirm any condition; your clinician interprets it alongside your symptoms, history, and other results. This page is general information, not medical advice.
Medicines that can move this result
It blocks the kidney tubules from secreting creatinine into the urine, so creatinine backs up in the blood while the actual filtering rate is unchanged. In healthy volunteers the reported average rise is 15% to 35%, and it reverses when the drug stops.
Source ↗It competes with creatinine for the same exit route out of the kidney tubule, so a little more creatinine stays in the blood. The label states plainly that this does not signify worsening kidney function.
Source ↗It lowers prostaglandins, the hormone-like signals that keep blood flowing through the kidney, which can cut kidney blood flow and let creatinine climb. The label names the people at greatest risk: impaired kidney function, heart failure, liver dysfunction, anyone on a diuretic or ACE inhibitor, and the elderly. Stopping the NSAID is usually followed by a return to the pretreatment state.
Source ↗It relaxes the vessel carrying blood out of each filtering unit, which lowers the pressure that drives filtration, so creatinine can tick up after starting or after a dose increase. The label puts this at about 2% of people treated with lisinopril alone for high blood pressure, and calls the rise minor and reversible on stopping.
Source ↗This triglyceride and cholesterol medicine raises serum creatinine in some people. The label says the increases tend to return to baseline after the drug is stopped, that the clinical significance is unknown, and that kidney function should be monitored in people at risk.
Source ↗Given by IV, it can cause acute kidney injury, mainly interstitial nephritis and less often acute tubular necrosis. Rising BUN and creatinine are how that injury shows up, which is why the label says to monitor both vancomycin blood levels and kidney function during treatment.
Source ↗The kidney clears this HIV and hepatitis B drug, and it can injure the tubules, the kidney's reabsorbing pipes. The label requires creatinine clearance to be calculated before starting and monitored during treatment, and lists increased creatinine among reported kidney reactions.
Source ↗Kidney injury is this chemotherapy drug's main dose-limiting toxicity and is linked to damage of the kidney tubules. The label reports it in 28% to 36% of people after a single 50 mg/m2 dose, first appearing in the second week, and says kidney function must return to normal before the next dose.
Source ↗Do not stop a prescribed medicine over a lab number. These are recognised associations, not a finding about your result — your value may have nothing to do with any medicine you take, and the list is not complete. Bring it to whoever prescribed the drug; they can weigh it against why you are taking it.
Frequently asked
- What does the Creatinine blood test measure?
- The creatinine blood test measures the amount of creatinine in your blood. Creatinine is a normal waste product your body makes when you use your muscles and some muscle tissue breaks down; healthy kidneys filter it out of the blood and remove it in urine. Because creatinine is removed from the body almost entirely by the kidneys, its level in the blood is used as a general indicator of how well the kidneys are working. It may be measured on its own or as part of a routine metabolic panel.
- What is a normal Creatinine blood test range?
- These figures are general reference values only and are not a personal cutoff or diagnosis. MedlinePlus lists a general normal range of about 0.7 to 1.3 mg/dL (62 to 115 µmol/L) for men and about 0.5 to 0.95 mg/dL (44 to 84 µmol/L) for women, and notes that women often have lower levels because they typically have less muscle mass. What is "normal" for you depends on factors such as muscle mass, body size, diet, age, and activity level. MedlinePlus states that "Normal value ranges may vary slightly among different laboratories," and that some labs use different measurements or test different samples. The reference range printed on your own lab report — and how your clinician interprets it for your age, sex, and health — is what applies to you. A normal result also does not always rule out kidney problems, since levels can stay normal in early kidney disease.
- What does a high result mean?
- This is a list of general possibilities, not a diagnosis or a complete list. A higher-than-normal creatinine level may be seen with kidney problems such as kidney damage or failure, kidney infection, reduced blood flow to the kidneys, or a blocked urinary tract, and can also be associated with conditions such as heart failure or diabetes. Importantly, MedlinePlus notes that a high level does not always mean a kidney problem — it may also be linked to dehydration, muscle disorders or muscle breakdown, intense exercise, a diet high in meat, or pregnancy-related conditions such as preeclampsia or eclampsia. Only a clinician can interpret what a high result means in your specific situation.
- What does a low result mean?
- Low blood creatinine levels are less common. When reported, a lower-than-normal level may be associated with malnutrition, with conditions that reduce muscle mass (including muscle or nerve disorders), or with serious liver disease. These are general possible associations, hedged and incomplete — not a diagnosis. A clinician interprets a low result in the context of your overall health.
Other lab tests
Sources
General reference, not medical advice, and not a substitute for your clinician. Lab reference ranges and interpretation depend on the laboratory and on your individual situation — discuss your results with a licensed healthcare professional.