An inborn error of ketone body catabolism resulting in intermittent episodes of ketoacidosis. The potential presence of cerebral edema, raised intracranial pressure, vomiting, and tachypnea makes this medical condition a serious clinical problem requiring immediate attention. There is no evidence that it is associated, as in older patients, with an uncontrolled diabetes mellitus.
SCOT Deficiency; Succinyl-CoA:3-Oxoacid-CoA Transferase Deficiency; Succinyl-CoA: Ketoacid-CoA Transferase Deficiency; Succinyl-CoA Acetoacetate Transferase Deficiency.
Less than 25 cases have been reported in the literature.
Autosomal recessive. Gene map location is chromosome 5p12-p13. Prenatal diagnosis can be made because cultured amniocytes have measurable succinyl-CoA:3-ketoacid CoA transferase (SCOT) activity.
SCOT, the key enzyme of ketone body utilization, is an extrahepatic mitochondrial matrix enzyme necessary for synthesis of acetoacetyl-CoA by transfer of a CoA moiety from succinyl-CoA to acetoacetate. Ketoacidosis is caused by SCOT deficiency resulting in reduced ketone body utilization.
Laboratory findings include SCOT deficiency, together with ketonuria. Normal levels of plasma amino acids, lactic acid, ammonia, glucose, and organic acids other than beta-hydroxybutyrate and acetoacetate are seen.
Severe intermittent ketoacidosis in ketogenic situations (fasting, febrile illness, any cause of stress) with no symptoms between episodes. There is persistent ketonuria, even in postprandial times. Age of onset is variable; however, a neonatal onset is common. The main clinical symptoms are vomiting, tachypnea, and cerebral edema (potentially raised intracranial pressure).
Precautions before anesthesia
Need to exclude diabetes mellitus and type I glycogen storage disease. It is highly recommended to ensure adequate fluid resuscitation and pharmacological treatment. Treatment consists of limiting protein intake, providing adequate calorie intake, and preventing aggravation of ketosis by providing alkaline therapy at the onset of any intercurrent infection. Check blood glucose, electrolyte levels, and blood gases with acid-base status.
Risk of pulmonary aspiration during induction of anesthesia is increased. The possible presence of associated cerebral edema and potentially raised intracranial pressure must raise significant concerns. It is important to control the electrolytes, especially when the patient is affected with severe vomiting and tachypnea. Maintain adequate hydration while closely monitoring blood gases in the perioperative period and postoperative recovery are paramount to the management of these patients.
No known specific pharmacological implications with this condition. Infections may exacerbate ketoacidosis further. The threshold to use antibiotics should therefore be low.
Other conditions to be considered
Other constitutional causes of ketosis in children (differential diagnosis is made by enzyme assay), and medical conditions part of this evaluation are: