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Five-minute Practitioner: October 2008

Only got five minutes? Then just read these key points on: inflammatory bowel disease, irritable bowel syndrome and familial hypercholesterolaemia

Only got five minutes? Then just read these key points on: inflammatory bowel disease, irritable bowel syndrome and familial hypercholesterolaemia

Inflammatory bowel disease

Ulcerative colitis (UC) and Crohn's disease together constitute inflammatory bowel disease (IBD).

UC always affects the rectum and then progresses to a variable extent around the colon, but never extends into the small bowel. Crohn's disease may occur anywhere in the GI tract.

Patients with distal colonic disease tend to present with rectal bleeding. This may be associated with the passage of mucus and/or diarrhoea, although if the disease is very distal the number of bowel motions may be normal or the patient may even be constipated, with bleeding being the predominant feature. Patients with more extensive colonic disease can present with bloody diarrhoea and the passage of mucus. Associated systemic symptoms including weight loss and lethargy may also be present. Small bowel Crohn's disease may present more insidiously, with generalised symptoms of weight loss, anorexia, tiredness and incidental iron deficiency anaemia.

Initially, FBC, U&Es, LFTs, CRP, tissue transglutaminase and ESR should be performed. Three stool samples should be sent for microscopy, culture and sensitivity.

The treatment of IBD depends on both its severity and its site.

Irritable bowel syndrome

IBS is not just a motility disorder of the colon but a condition that affects the whole length of the GI tract.

In the past, the psychological aspects of the condition have probably been overemphasised. Stress does not cause IBS, although it affects consultation behaviour and exacerbates the condition.

The principal symptoms of IBS are abdominal pain, which can occur at any site; abdominal bloating, which may be accompanied by an actual increase in girth; and a disturbed bowel habit: about one-third of patients have constipation, one-third diarrhoea and one-third alternate between the two. Many patients also complain of non-colonic symptoms.

All patients with suspected IBS should have an FBC, ESR or plasma viscosity, CRP and serological screening for coeliac disease.

Familial hypercholesterolaemia

Familial hypercholesterolaemia (FH) has an autosomal dominant pattern of inheritance and the most common mutation involves the LDL receptor.

It is estimated that heterozygous FH affects 1 in 500 people in the UK but the vast majority remain undiagnosed, with only 15,000 patients currently identified. It can result in significantly raised LDL cholesterol levels and if left untreated patients have a high risk of premature CHD, with a >50% risk in men by the age of 50 and >30% in women by the age of 60. If treated early, most patients will have a normal life expectancy.

Homozygous FH is a rare condition, with an estimated prevalence of one in a million in the UK. In homozygous FH plasma LDL cholesterol can exceed 10mmol/l. Symptoms become apparent in childhood and patients are at risk of early coronary mortality.

The guideline suggests that FH should be suspected in adults with a total cholesterol >7.5mmol/l, especially if there is a strong personal or family history of premature CHD. GPs should confirm that the LDL cholesterol is >4.9mmol/l on two blood samples. Other causes of hypercholesterolaemia, such as thyroid, renal and hepatic disease, should be excluded before a diagnosis of FH is made.

The diagnosis should be formalised using the Simon Broome criteria.

A clinical diagnosis of homozygous FH should be considered in adults with an LDL cholesterol >13mmol/l and in children with an LDL cholesterol >11mmol/l.

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