Differential Diagnosis of an Infant or Child Presenting with Acidosis and/or Ketosis

Description

An infant or child presenting with acidosis and/or ketosis may have an inborn error of metabolism or simply a physiologic response to fasting, vomiting or diet. By looking at the pattern of laboratory test findings some possible explanations for the patient's condition can be identified.

Presenting groups:

(1) metabolic acidosis with ketosis

(2) metabolic acidosis without ketosis

(3) ketosis without metabolic acidosis

Metabolic acidosis:

(1) pH < 7.30

(2) PCO2 < 30 mm Hg

(3) serum bicarbonate < 15 mmol/L (mEq/L)

Ketosis: ketonuria, increase in ketone bodies

Metabolic Acidosis with Ketosis

Glucose Levels	Additional Testing	Diagnostic Considerations
increased	high ammonia	ketolytic defects
increased	normal or low ammonia	branched chain organic acidurias
normal	high lactate	congenital lactic acidosis respiratory chain disorders organic acidurias
normal	normal lactate	maple syrup urine disease, late onset form ketolytic defects organic acidurias short chain acylCoA dehydrogenase
decreased	high lactate often with hepatomegaly	gluconeogenesis defects respiratory chain defects
decreased	normal lactate	maple syrup urine disease, late onset form branched chain organic acidurias acetoacetyl CoA thiolase adrenal insufficiency

Metabolic Acidosis without Ketosis

Lactate	Glucose	Diagnostic Considerations
increased	normal	pyruvate dehydrogenase deficiency
increased	decreased	fatty acid oxidation disorders hydroxymethylglutaryl-CoA lyase glucose 6 phosphatase deficiency fructose biphosphatase deficiency
normal	normal	renal tubular acidosis I and II pyroglutamic aciduria

Ketosis without Metabolic Acidosis

Glucose Levels	Additional Testing	Diagnostic Considerations
normal glucose	intermittent ketosis	fasting catabolism recurrent vomiting (physiologic ketonuria) short chain acyl CoA dehydrogenase hydroxy short chain acyl dehydrogenase
normal glucose	permanent ketosis	medium chain triglyceride enriched diet and ketotic diet ketolytic defects
fasting hypoglycemia	with hepatomegaly and post-prandial hyperlactacidemia	glycogenosis type III glycogen synthetase deficiency
fasting hypoglycemia	without hepatomegaly	recurrrent ketotic hypoglycemia hypoglycemia due to adrenal disorders hydroxy short chain acyl dehydrogenase medium chain acyl CoA dehydrogenase glycogen synthetase deficiency ketolytic defects

ketolytic defects: oxoacyltransferase deficiency, thiolase deficiency

branched chain organic acidurias: methylmalonic acid (MMA), propionic acid (PA), isovaleric acid (IVA)

congenital lactic acidosis: pyruvate carboxylase (PC) deficiency, multiple carboxylase deficiencies, ketoglutarate dehydrogenase (KGDH) deficiency, lipoamide oxidoreductase (E3) deficiency

gluconeogenesis defects: fructose diphosphatase (FDP) deficiency, glucose 6 phosphatase (G6P) deficiency, glycogen synthase deficiency

organic acidurias: 3-hydroxyisobutyric aciduria, others

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Description

Specialty

ICD-10