Are your creatinine levels normal? How to tell and what to do if they're high

• Creatinine levels are measured to gauge how well a person's kidneys are functioning.
• Normal creatinine levels are between 0.7 to 1.3 mg/dL for men, and 0.6 to 1.1 mg/dL for women.
• To lower your creatinine levels, manage chronic conditions, stay hydrated, and drink water.

Creatinine is a waste product of normal muscle activity, specifically the breakdown of the amino acid derivative creatine.

The evaluation of creatinine levels is a common way for doctors to assess someone's kidney health. A healthy kidney filters waste products like creatinine out of the blood to exit out of the body in urine. If your kidneys aren't working properly creatinine can build up in the blood, which could be a sign of kidney disease.

"A lot of systemic type diseases like kidney disease, chronic heart disease, and diabetes can cause an elevation in creatinine levels," says S. Adam Ramin, MD, a urologist and medical director of Urology Cancer Specialists. "Because of that, creatinine level tests can help us determine the general health of a person."

Here's how to read the results of a creatinine test, and depending on those results, how to lower your creatinine levels.

What is a creatinine test?

A creatinine test measures creatinine levels in your blood and is typically part of the blood work panel you get at an annual physical, says Christopher Brede, MD, a urologist with Spectrum Health.

However, in some cases, doctors will order a creatinine test outside of regular blood work if they suspect a kidney issue, Brede says.

There are four types of creatinine tests:

1. Creatinine urine test, which collects your urine over a 24-hour period.
2. Creatinine blood test (serum creatinine) is the most common type and measures the level of creatinine in the blood.
3. Creatinine kinase, which measures how much creatinine kinase, a type of protein, is in the blood. This is used to diagnose conditions like muscular dystrophy and other illnesses that cause abnormal breakdown or inflammation of the muscles.
4. Creatinine clearance test, which involves a blood draw and 24-hour urine collection. It offers a more in-depth analysis of creatinine levels and kidney function. Doctors may order it when they're concerned about kidney or heart disease.

How to interpret your creatinine levels

In general, normal levels for a creatinine blood test are:

• Males: 0.7 to 1.3 milligrams per deciliter (mg/dL)
• Females: 0.6 to 1.1 mg/dL

However, what's considered normal can vary based on a person's size, muscle mass, age, and race. Therefore, "patients should inquire with their health care provider what an expected level would be for them individually," Brede says.

This is especially true since slightly elevated levels might not indicate an underlying health problem, says Ramin. In fact, creatinine levels can temporarily rise due to intense exercise, which is why you should inform your doctor if you've done an intense workout in the past two days before the test.

If your levels are above 1.2 for women or 1.4 for men, your kidneys may not be functioning properly. Kidney failure may occur in the range of 6 to 10 mg/dL, Ramin says, but largely depends on the person. For example, some people may experience kidney failure at 3 mg/dL.

If your creatinine blood test shows elevated levels, a creatinine clearance test may be ordered since they can give a more in-depth analysis of kidney health.

How to lower creatinine levels

If your creatinine levels are elevated, you should work with your doctor to understand why they're high, Brede says. That will help you determine how to lower them.

Some ways you may be able to lower your creatinine levels include:

• Managing chronic diseases. Since chronic health conditions like diabetes and high blood pressure are risk factors for kidney disease, managing them may lower creatinine levels, says Brede.
• Avoiding creatine supplements, which one case study linked to higher creatinine levels, likely due to the fact creatine breaks down into creatinine.
• Staying hydrated: Drinking 125 ounces of water a day for men and 91 ounces for women may reduce creatinine levels by helping the kidneys filter waste more efficiently, says Ramin.
• Eating more fiber: A small 2013 study found that people with kidney disease who ate 23 grams of fiber per day had lower creatinine levels than they did while eating a lower-fiber diet.
• Decreasing meat consumption. A small 2014 study of both healthy people and those with diabetes and kidney disease found that people who ate a meat-based meal had temporarily higher creatinine levels than those who ate a non-meat meal with a similar amount of protein. Therefore, eating meat occasionally shouldn't be a problem, but consistent meat consumption may elevate levels.
• Changing medications. Several medications, including some antibiotics and antihistamines, can raise creatinine levels.

Insider's takeaway

Creatinine tests measure the amount of creatinine in your bloodstream or urine to determine how well your kidneys are working. While creatinine tests are part of routine blood panels, your doctor may order them more frequently if you have an underlying condition like diabetes or heart disease.

What's "normal" in terms of creatinine levels will vary depending on multiple factors, like muscle mass, gender, and age. Even your diet and exercise routine can temporarily elevate creatinine levels. However, in general, creatinine levels above 1.2 mg/dL for women and 1.4 mg/dL for men may be a sign of impaired kidney function.

If your creatinine test comes back with elevated levels, talk to your doctor about what may be causing it and how you can best address it. They may suggest you alter your diet or modify your medications.