Calprotectin and ulcerative colitis: what it shows

Calprotectin is released by certain white blood cells when the bowel is inflamed. A stool sample can therefore help a clinician distinguish inflammation from some non-inflammatory causes of bowel symptoms. An elevated result may occur with ulcerative colitis, infection, some medicines or other bowel conditions. A result in a lower range makes active inflammation less likely, but interpretation depends on symptoms, age, medicines and the laboratory’s range.

Provide the sample exactly as instructed and tell the clinician about diarrhoea, blood, abdominal pain, recent infection and medicines such as anti-inflammatory painkillers. Do not stop prescribed treatment without advice. The clinician may repeat the test, arrange blood tests, or refer you for further assessment. Results are considered alongside your history and examination; they do not replace an endoscopic assessment when one is needed.

Seek urgent care for heavy rectal bleeding, severe or worsening abdominal pain, a swollen abdomen, repeated vomiting, fainting or signs of dehydration. Arrange a GP consultation for persistent diarrhoea, blood or mucus in stool, unexplained weight loss, night-time symptoms or recurrent abdominal pain. Prompt review helps distinguish a flare from infection and other causes.

Ask what your result means in the context of your symptoms, whether medicines or infection could affect it, and whether you need a repeat sample, specialist review or endoscopy. Ask how to recognise a possible ulcerative colitis flare.