A6-month-old male infant was sent to a quaternary referral hospital from a tertiary referral hospital with a possible diagnosis of a fatty acid oxidation disorder.
HISTORY OF PRESENTING ILLNESSThe infant was well until 4 weeks before admission at the quaternary referral hospital. He, along with the rest of his family, experienced an acute gastroenteritic illness with vomiting and watery diarrhea. Although his siblings and parents recovered, he did not, and because of concerns of a presumed secondary lactose intolerance he was changed from his usual Similac (Ross Products, Abbott Laboratories, Columbus, Oh) formula to a soy-based formula (Alsoy, Nestle Inc, Eau Claire, Wisc) about one week into his illness. He became more lethargic and hypotonic with persisting vomiting and diarrhea, and was admitted to a tertiary referral hospital.
PAST HISTORYHe was born to nonconsanguineous parents of Italian (father) and Hungarian-French (mother) descent. He had two female siblings both of whom had been well in the past, and there was no family history of notable diseases. During pregnancy his mother had a laparoscopic cholecystectomy at 20 weeks' gestation, and he was born by Cesarean delivery at term because of fetal bradycardia. There were no other problems in the perinatal period. He had been well before this current illness, with appropriate growth parameters and development. He was fed a combination of breast milk and formula (Similac, Ross Pharmaceuticals). Cereals were introduced at 5 months along with other age-appropriate foods such as bananas and some vegetables.
TERTIARY REFERRAL HOSPITALSymptoms of diarrhea and poor feeding had persisted for approximately two weeks before admission to the tertiary referral hospital, where he was found to be weak, floppy, and lethargic but easily rousable. He had massive hepatomegaly, with the liver edge palpable in the right iliac fossa, which had not been previously noted on several abdominal examinations. There was no splenomegaly, ascites, or signs of chronic liver disease. He was not clinically jaundiced despite elevated conjugated bilirubin. An Escherichia coli urinary tract infection (UTI) was Initial hematology and biochemical results are shown in Tables I and II. Of note is the presence of hypoglycemia, hypokalemia, hypophosphatemia, low plasma carnitine levels, hepatic dysfunction and coagulopathy. Other investigations that were normal included venous blood gas, plasma lactate, amino acids, creatine kinase, galactosemia screen, and routine urinalysis (ketones negative). Gas chromatography mass spectroscopy analysis of urinary organic acids showed elevated dicarboxylic acids with hypoketosis at the time of hypoglycemia. Urinary succinylacetone was negative. Serology for hepatitis viruses A, B, and C was negative. An echocardiogram demonstrated thickening of the interventricular septum, suggestive of a possible cardiomyopathy. An abdominal ultrasonogram showed an enlarged, heterogeneous liver with increased echogenicity and normal portal flow. A liver biopsy was performed ...