Anesthetic implications of the child with homocystinuria.

We present a 7 1/2-year-old girl with type I homocystinuria who required anesthetic care during repair of bilateral ectopia lentis. Homocystinuria is an autosomal recessive disorder and represents the second most common error of amino acid metabolism. Defective function of the enzyme cystathionine synthetase results in elevated serum levels of methionine and homocysteine. Physiologic disturbances include an increased risk of thromboembolic events and hypoglycemia. Perioperative measures to prevent thromboembolic events include diet therapy to lower serum methionine and homocysteine levels, adequate preoperative hydration, maintenance of intraoperative cardiac output, and the use of pneumatic stockings to prevent peripheral stagnation of blood. Hypoglycemia is thought to be due to alterations in insulin release associated with high levels of circulating sulfur-containing amino acids such as methionine. Perioperative measures include normalization of serum methionine and administration of exogenous glucose during periods of fasting.