Disorders of the serum lipoproteins. II. Hyperlipoproteinaemic states

Hyperlipidaemia in children

Hyperlipidaemia in children is most commonly expressed as hypercholesterolaemia. "Normal values" for serum cholesterol, if defined statistically, vary between communities, and levels of cholesterol in childhood above which an increased risk of coronary heart disease in adult life may be expected have not been firmly established. It is suggested that serum cholesterol concentration over 250 mg/dl (6.47 mmol/l) in a child over 1 year of age merits detailed investigation, including full lipoprotein analysis, and levels of serum cholesterol between230 and 250 mg/dl (5.95-6.47 mmol/l) should be repeated with further studies if indicated. Secondary hyperlipoproteinaemia rarely presents diagnostic problems but must always be excluded. The only primary hyperlipoproteinaemia likely to be encountered in childhood is familial hyperbetalipoproteinaemia in its common heterozygous form. The most effective means to date of lowering serum cholesterol in this condition is cholestyramine, but the long-term consequences of therapy are not known and treatment should at present be limited to children from high-risk families. Long-term follow-up is essential and until results of such studies are available population screening is unjustified.

Classification of hyperlipidaemias

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Medium chain triglycerides in paediatric practice

Medium chain triglycerides (MCT) bypass the steps necessary for the absorption of long chain fats (LCT), and so have theoretical grounds for their use in various disease states, particularly malabsorptive disorders. In childhood, MCT have particular advantages since they allow restriction of dietary long chain fats without limiting the intake of protein necessary for growth while providing adequate calories. In malabsorptive states, MCT have been used mostly in cystic fibrosis, where they may reduce steatorrhoea. However, the long-term growth patterns of these children are dependent on the extent and severity of their chest disease. MCT may be a useful source of calories for those with anorexia due to infection or liver disease and in babies recovering from meconium ileus. The decrease in offensive stools, flatus, and abdominal discomfort improves well-being and social acceptability which is important for many schoolchildren and adolescents. Rectal prolapse may be helped. Where there is loss of the small intestinal absorptive surface, particularly after massive small bowel resection, MCT can help to maintain weight and nutrition. They may also be a useful supplementary nutritional measure in patients severely affected with coeliac disease while awaiting response to a gluten-free diet, and in patients with regional enteritis. In children with liver disease, MCT provide a ready source of calories while avoiding the loss of fat in their stools. Infants with neonatal hepatitis or biliary atresia remain well nourished, and some older children with liver disease grow more rapidly and have fewer and less offensive stools and less abdominal discomfort. Where an abnormal number of faecal organisms colonize the small intestine (`contaminated small bowel syndrome' or `blind loop syndrome') intraluminal bile salts become deconjugated and cause steatorrhoea. A combination of antibiotic and surgical treatment is usually indicated, but MCT can be used to improve nutrition before operation and may be indicated for associated conditions, such as massive intestinal resection. MCT have also been helpful in patients with defective chylomicron formation due to a-β-lipoproteinaemia. In the congenital and less commonly encountered acquired lymphatic disorders in childhood, MCT have given encouraging results. This group includes patients with gross protein and fat loss due to intestinal lymphangiectasia and others with lymphatic anomalies at other sites. Hyperchylomicronaemia (familial fat-induced hypertriglyceridaemia) responds well to dietary treatment with MCT.