High creatinine: what it means and what to do

Creatinine is a waste product made when your muscles use energy. According to MedlinePlus, the kidneys remove it from the body in urine. If the kidneys aren’t working well, creatinine builds up in the blood and the number goes up.

The normal level depends on body size and muscle mass, which is why women usually have lower levels than men, and every lab uses its own range. This page explains the tests in general; what your result means is something the doctor explains in your visit. To understand other tests, see how to read your lab results.

The NIDDK explains that kidney function is checked with two tests, and creatinine is used to calculate the first:

• Estimated glomerular filtration rate (eGFR): calculated from creatinine, it shows how well your kidneys filter. According to the NIDDK, 60 or more is in the normal range, under 60 may mean kidney disease, and 15 or less is called kidney failure.
• Urine albumin (albumin-to-creatinine ratio): a healthy kidney lets almost no albumin through. According to the NIDDK, 30 mg/g or less is normal and more than 30 may be a sign of damage; it is often repeated to confirm.
• Blood creatinine: goes up when the kidneys filter less.

According to MedlinePlus, creatinine can rise because of:

• Kidney disease, sudden or chronic
• Dehydration: see dehydration, common in Puerto Rico’s heat
• Something blocking the flow of urine
• Muscle damage
• Some medicines that affect the kidney or the test result
• Pregnancy problems such as preeclampsia

MedlinePlus explains that diabetes and high blood pressure are the two most common causes of chronic kidney disease. Diabetes is very common in Puerto Rico: according to a CDC analysis, 14.4% of adults had diagnosed diabetes in 2021, the highest of any US state or territory. The NIDDK also notes that Hispanic people are more likely to develop kidney failure.

The NIDDK recommends a kidney check every year if you have diabetes, and asking your doctor how often if you have high blood pressure, heart disease or a family history of kidney failure. See type 2 diabetes and high blood pressure.

You see Dr. Diana Nieves Castro, MD, a Puerto Rico–licensed general practice physician with several years of emergency-department experience, in English or Spanish. She reviews your results with you, your history of diabetes and blood pressure, how much water you drink and all your medicines and supplements.

We evaluate, diagnose and treat. If needed, we give you a lab order to repeat creatinine, calculate eGFR, check urine albumin and other tests such as potassium at a lab near you. If appropriate, the doctor adjusts your medicines and we send your prescription to your pharmacy. For diabetes and blood pressure, see chronic care.

According to the NIDDK, your primary care doctor refers you to a nephrologist (kidney specialist) if your case is complicated, if the disease is getting worse quickly or if it is advanced. If you need a kidney ultrasound, we refer you for that too.

Price. Results from another doctor or lab are reviewed in a US$79 doctor visit. The US$49 follow-up visit is for reviewing results of labs our doctor ordered. Request a visit online 24/7 — we confirm your time by email or text.

Anti-inflammatory pain relievers (NSAIDs). The NIDDK warns that ibuprofen, naproxen and other anti-inflammatories, which are also in many cold medicines, can damage the kidneys, especially if you already have kidney disease, diabetes or high blood pressure. Ask the doctor what you can use for pain.

Metformin. According to MedlinePlus, your doctor checks your kidney function before and during metformin treatment, and with kidney disease it sometimes should not be used. Don’t stop it on your own: the doctor reviews your case.

Supplements and remedies. MedlinePlus advises checking with your doctor before taking any over-the-counter medicine, vitamin, herb or supplement if you have kidney disease.

MedlinePlus explains that chronic kidney disease often causes no symptoms until it is advanced, so testing is the only way to know. When symptoms appear, they can include the ones below (muscle cramps also have many other causes):

• Tiredness and feeling unwell
• Poor appetite and nausea
• Itching and dry skin
• Swelling of the hands, ankles or feet
• Peeing less, or getting up at night to pee
• Cramps or trouble concentrating

For your safety, go to the emergency room or call 911 if:

• You are barely peeing or have stopped peeing
• You have swelling with shortness of breath
• The lab tells you your potassium is very high, or you have palpitations or faint
• You have confusion, seizures or vomiting that won’t stop