Specific Management: Metabolic Illness

Children may present in a variety of ways, including reduced level of consciousness. Four main metabolic causes are briefly described here.

Hyperglycaemia

Diabetic ketoacidosis is diagnosed if capillary glucose is >11, pH<7.3 and ketones in the urine. This should be managed as per the NICE guidelines. [16]

Hypoglycaemia

A metabolic cause should be considered if blood glucose less than 2.6 mmol/l.

Past medical history of consanguinous relationship should be sought. The child should be examined to look for physical clues which may suggest an underlying metabolic problem, such as dysmorphism, hypotonia, failure to thrive and enlarged liver.

The causes of hypoglycaemia in children include severe sepsis, exogenous or endogenous insulin excess, disorders of hormone production: Addison’s disease, growth hormone deficiency or congenital adrenal hyperplasia, disorders of fatty acid oxidation e.g. medium chain acyl CoA dehydrogenase deficiency (MCAD), organic acidurias/acidaemias and glycogen storage disorders. [1]

Treatment of hypoglycaemia

As per APLS [5] guidelines, the treatment is with 2 ml/kg of 10% dextrose bolus. An infusion of 10% dextrose solution should be given to maintain normal blood glucose: between 4-7 mmol/l.

Hyperammonaemia

High ammonia levels are neurotoxic. A plasma ammonia level of 200 micromol/l is significantly raised and needs actively treating.   The higher the peak or the longer the level remains high the worse the prognosis.  A level of 200 micromol/l can be reduced with a sodium benzoate infusion.  If the levels remain high or are greater than 500 micromol/l, emergency haemodialysis is required. [5]

Non-hyperglycaemic ketoacidosis

Inherited conditions: organic acidopathies, amino acidopathies, fatty acid oxidative defects, mitochondrial electron transport chain defects and urea cycle enzyme defects can present as acute encephalopathy with a pH <7.3 and ketones in the urine.

Further investigations include plasma lactate, plasma and urinary amino acids and urinary organic acids.  Advice should be sought from a metabolic medicine unit and careful monitoring of fluid balance to avoid raised intracranial pressure is required.