What does high creatinine mean?

Creatinine is a waste product made by your muscles. Healthy kidneys remove most creatinine from the blood and pass it into the urine. When a blood test shows a high creatinine, it can be a clue that the kidneys are not filtering as well as expected - but the number must always be interpreted in context.

Does a high creatinine always mean kidney disease?

No. Creatinine can rise because of dehydration, certain medicines, a recent illness, urinary blockage, very strenuous exercise, or a large muscle mass. It can also rise because of acute kidney injury or chronic kidney disease. This is why one isolated result rarely tells the whole story.

What matters more than the number alone?

The trend is extremely important. A creatinine of 150 micromol/L may mean something very different in a person whose usual level is 70 compared with someone whose level has been around 150 for years. Doctors also look at eGFR, urine protein, blood pressure, medications, previous results and sometimes a kidney ultrasound.

What should happen next?

If your creatinine is unexpectedly high, the usual next step is to confirm the result and look for a cause. This may include repeating the blood test, checking urine for protein or blood, reviewing medicines such as anti-inflammatory painkillers, assessing hydration and blood pressure, and deciding whether imaging or specialist review is needed.

When is it urgent?

Seek prompt medical assessment if a high creatinine is accompanied by very little urine, severe vomiting or diarrhoea, marked swelling, shortness of breath, confusion, severe weakness, or a known very high potassium level. These may indicate a more significant disturbance in kidney function or body chemistry.