High creatinine: what does it mean?

Maybe you had a routine check at work, a medical before travel, or tests at a hospital outpatient clinic. The report came back from the lab with creatinine marked H for high, and now you are wondering what it means. Some people describe it simply as "creatinine iko juu".

This guide explains the test in plain language. It covers what creatinine is, why a result can be high, what other information a clinician usually looks at, and how to find appropriate follow-up in Mombasa. It is written to help you understand your result and prepare for a conversation with a doctor. It is not a diagnosis.

What creatinine is

Your muscles use a substance called creatine to store energy. Every day, a small, fairly steady amount of it breaks down into creatinine, a waste product that passes into the blood. The kidneys filter creatinine out of the blood and it leaves the body in urine.

Because muscles make creatinine at a fairly steady rate, the level in the blood stays fairly stable from day to day in a healthy person. If the kidneys filter less well, creatinine can build up and the blood level rises. That is why it is used as a marker of kidney function.

The amount you make depends mostly on how much muscle you have. A young, muscular man will usually have a higher creatinine than an older woman with less muscle, even if both have healthy kidneys. This is one reason there is no single "normal" number for everyone.

In Kenya, most labs report creatinine in micromoles per litre (µmol/L). Some reports use milligrams per decilitre (mg/dL). The numbers look very different, so always compare your result with the reference range and unit printed on your own report.

Why doctors measure it

Creatinine is one of the most common blood tests in the world. It is cheap, widely available, and gives useful information about how well the kidneys are filtering. A doctor may request it:

• as part of a routine check or a general blood panel, often labelled "U&E", "UECs" or "renal function tests";
• because you have a condition that can affect the kidneys, such as diabetes or high blood pressure (many people call this presha);
• before starting, or while taking, medicines that are cleared by the kidneys or that can affect them;
• when you are unwell, dehydrated or in hospital, to check that the kidneys are coping;
• to follow kidney function over time in someone already known to have a kidney condition;
• before some scans that use contrast dye.

The main value of creatinine is that it is used to calculate eGFR, the estimate of kidney filtering. More on that below.

Why a result may be high

A creatinine result above the lab's reference range can have many explanations. Some involve the kidneys and some do not. Your clinician will think about which ones fit your situation. The list below is to help you understand that conversation, not to work out the cause yourself.

Reasons that are not about kidney damage

• Dehydration. If you have not been drinking enough, have had vomiting or diarrhoea, or have been sweating heavily in the Mombasa heat, the kidneys receive less blood flow and creatinine can rise. This often improves once you are well hydrated, although a clinician will still want to check.
• High muscle mass. People with a lot of muscle, such as manual workers, athletes and bodybuilders, naturally make more creatinine.
• Recent heavy exercise. Hard training or physical work in the day or two before the test can raise the level for a short time.
• A large meat meal. Cooked meat contains creatine and creatinine. A big serving of nyama choma or other meat in the hours before a blood test can push the result up for a while. Creatine supplements used for gym training can do the same.
• Some medicines. A few medicines raise creatinine in the blood by stopping the kidneys from releasing it into the urine, without harming kidney filtering. Examples include trimethoprim (part of co-trimoxazole, often called Septrin) and some HIV medicines. Other medicines can genuinely reduce kidney function in some situations (see below). Only a clinician can tell these apart.
• Lab and sample factors. Different labs use different methods, and results can vary slightly between them. Some substances in the blood can interfere with some methods, and a delay before the sample is processed can affect the result. Small differences between two labs are expected.

Reasons that involve the kidneys

• A sudden drop in kidney function, called acute kidney injury (AKI). This can happen with severe dehydration, serious infections, some medicines, or a blockage to urine flow. It develops over hours or days and often needs prompt medical attention.
• Chronic kidney disease (CKD), a long-term reduction in kidney function or kidney damage lasting more than 3 months. Common causes include diabetes and high blood pressure.
• Medicines that can affect kidney function, especially anti-inflammatory painkillers (NSAIDs) such as ibuprofen and diclofenac, particularly when someone is also dehydrated or taking certain blood pressure medicines or water tablets. Some blood pressure medicines also cause a small, expected rise in creatinine when first started, which doctors check with a repeat test.
• Blockage to urine flow, for example from an enlarged prostate or kidney stones.
• Other kidney conditions, such as inflammation of the kidney filters (glomerulonephritis) or inherited kidney conditions.

For a fuller explanation of each reason, read causes of high creatinine.

Why one result doesn't tell the whole story

A single blood test is a snapshot of one moment. Many of the factors above can change from one day to the next. So clinicians rarely make a decision about kidney health based on one creatinine number. Instead, they usually ask:

• Is there an older result to compare with? A result that has been stable for years means something different from one that has jumped recently. Bring any old reports you have, even from other hospitals or labs.
• Does it stay high when repeated? A repeat test, often after a few days or weeks depending on the situation, shows whether the first result was a one-off.
• What is the eGFR? The creatinine number is turned into an estimate of kidney filtering that takes account of age and sex.
• What does the urine show? A urine albumin test (ACR) can show kidney damage even when creatinine and eGFR look normal.
• How are you? Symptoms, other illnesses, medicines and blood pressure all help to explain the result.

It also works the other way. A creatinine within the lab range does not always mean the kidneys are fully healthy. Someone with low muscle mass, such as an older or very slim person, may have a "normal-looking" creatinine even when kidney filtering is reduced. This is another reason eGFR and urine tests matter.

eGFR and kidney function

GFR stands for glomerular filtration rate. It describes how much blood the kidneys filter each minute. Measuring GFR directly is complicated, so labs estimate it. This estimate is called eGFR.

International guidance from KDIGO (Kidney Disease: Improving Global Outcomes) recommends estimating GFR with a validated equation, rather than judging kidney function from creatinine alone. The equation combines your creatinine result with your age and sex. A common one is the CKD-EPI equation. Many Mombasa labs print the eGFR next to the creatinine. If yours does not, a clinician can calculate it.

A higher eGFR means better filtering. The relationship with creatinine is not a straight line: when kidney filtering falls, creatinine rises slowly at first and then more steeply. A small change in creatinine can therefore reflect a meaningful change in eGFR.

In some people eGFR based on creatinine is less reliable, for example those with very high or very low muscle mass, amputations, or some long-term illnesses. KDIGO suggests that clinicians may then use another blood marker, cystatin C, to get a more accurate estimate. Not every lab offers this test.

Read more in eGFR explained and the creatinine test.

Other tests that may be relevant

Because creatinine is only one piece of the picture, clinicians often add other tests. Which ones depends on your history and examination. Common ones include:

• Urine albumin-to-creatinine ratio (ACR). Albumin is a protein that healthy kidneys keep in the blood. Finding it in the urine is an early sign of kidney damage. KDIGO recommends assessing ACR alongside eGFR. See urine ACR test.
• Urinalysis (urine dipstick and microscopy). Checks for blood, protein, sugar and signs of infection. See urinalysis.
• Urea and electrolytes, including sodium and potassium. These are often run in the same panel as creatinine.
• Blood sugar and HbA1c, to check for diabetes, which is a common cause of kidney disease.
• Blood pressure checks, sometimes repeated or measured at home.
• Full blood count, as long-term kidney disease can cause anaemia (low haemoglobin).
• Kidney ultrasound, which shows the size and shape of the kidneys and can reveal a blockage. See kidney ultrasound.

When a clinician looks at kidney health, KDIGO groups urine albumin results into three categories:

Kidney risk is judged by combining the eGFR category (G) and the albuminuria category (A). For a single overview, see kidney function tests.

When follow-up may be appropriate

Follow-up is common after a creatinine result outside the reference range. It does not mean something serious has been found. It means a clinician wants more information. Follow-up may be especially appropriate if:

• your creatinine is above the lab range, or your eGFR is below 60;
• there is albumin, protein or blood in your urine;
• you have diabetes, high blood pressure, heart disease, or a family history of kidney disease;
• your result has risen compared with an earlier one;
• you take long-term medicines that can affect the kidneys, including regular painkillers;
• you have symptoms such as swelling of the feet or face, foamy urine, or changes in how much you pass urine.

Follow-up usually starts with a general doctor or physician, who may repeat the test, order a urine ACR, review your medicines and check your blood pressure. Some people will later be referred to a nephrologist. Guidelines suggest specialist input in situations such as a very low eGFR (below 30), a high level of albumin in the urine, a fast fall in kidney function, or a sudden unexplained rise in creatinine. Read when to see a nephrologist.

CKD is only diagnosed when kidney changes are present for more than 3 months. So a clinician will often want at least two results some time apart before using that term.

When to discuss results with a healthcare professional

It is a good idea to discuss any creatinine result marked high, or any eGFR below the range on your report, with a doctor or clinical officer. That is true even if you feel well, because early kidney changes usually cause no symptoms. Try to arrange this within the next few weeks, or sooner if your doctor or lab has asked you to.

To make the appointment useful, bring:

• the lab report, and any earlier kidney results you have;
• a list of all your medicines, including painkillers, herbal remedies and supplements;
• your recent blood pressure and blood sugar readings, if you have them;
• a note of any symptoms and when they started.

Our list of questions to ask your doctor can help you prepare, and what to do after a high creatinine result walks through the steps.

Find kidney care in Mombasa

Kidney tests and follow-up are available across Mombasa, including on Mombasa Island, in Nyali, Bamburi, Likoni and Changamwe. Options include hospital outpatient clinics, private laboratories, general practitioners, physicians and nephrologists. The right starting point depends on your result and your health.

• If you need a test or a repeat test, see kidney testing in Mombasa.
• If your doctor has suggested a kidney specialist, see nephrologists in Mombasa.
• For an overview of services, see kidney care in Mombasa.

Explore the high creatinine guide

Each page below goes deeper into one question.

Frequently asked questions

Does high creatinine mean I have kidney disease?

Not on its own. A single high creatinine result can have several explanations, including dehydration, high muscle mass, a recent large meat meal, hard exercise, some medicines and differences between lab methods. Kidney disease is assessed using eGFR and a urine albumin test (ACR) together, and chronic kidney disease is only diagnosed when changes last for more than 3 months. A clinician puts these pieces together.

What is a normal creatinine level?

There is no single normal number for everyone. Reference ranges differ between labs and depend on age, sex and muscle mass. Use the range printed on your own report, and ask your clinician what your result means for you.

Can drinking more water lower my creatinine?

If a result was raised because you were dehydrated, it may come down once you are well hydrated. Drinking large amounts of water does not repair the kidneys, and some people with kidney or heart conditions are advised to limit fluids. Ask your clinician how much you should drink before a repeat test.

Should I repeat the creatinine test?

Repeating the test is a common next step, because one result is a snapshot. Your clinician will decide when to repeat it and whether to add other tests such as a urine ACR. It helps to repeat it in similar conditions: well hydrated, and without very hard exercise or a large meat meal in the day before.

Is creatinine the same as eGFR?

No. Creatinine is the blood test. eGFR is an estimate of how well the kidneys filter, calculated from your creatinine together with your age and sex using a validated equation. Many labs print both on the same report.

Do I need to see a kidney specialist for high creatinine?

Many people with a raised creatinine are first assessed and followed up by a general doctor or physician. Referral to a nephrologist (kidney specialist) may be considered in some situations, for example when eGFR is very low, when there is a lot of albumin in the urine, or when kidney function is falling quickly. Your doctor can advise on this.

Can I get creatinine tested in Mombasa?

Yes. Creatinine is a routine blood test offered by many hospital labs and private laboratories in Mombasa. Kidney testing is usually most useful when a clinician has requested it and will review the result with you.

This page explains what a test or condition involves. It is not a diagnosis and does not replace advice from a doctor who knows your history. Your results should be interpreted together with your symptoms, other tests and a clinical assessment. Medical disclaimer.