Not all sugars are equal: galactose interference leading to false hyperglycaemia in a case of classical galactosaemia.

OBJECTIVES: Classical galactosaemia (OMIM #230400) is an inborn error of carbohydrate metabolism caused by deficiency of the enzyme galactose-1-phosphate uridyl transferase (GALT). CASE PRESENTATION: We report a case of a female infant who presented with vomiting, failure to thrive, hepatic transaminitis and a discrepancy between point-of-care (POC) glucometer (Accu-chek® Inform II, Roche Diagnostics, Germany) and capillary blood glucose (ABL90 Flex Plus© blood gas analyser) testing results, raising the suspicion for a diagnosis of classical galactosaemia. This was attributed to suspected analytical interference from markedly elevated blood galactose, due to a known limitation of the POC glucometer specificity for the monosaccharide sugars glucose and galactose. This led to falsely elevated glucose readings on POC glucometer testing in the presence of a high galactose concentration. Reduced GALT enzyme activity and genetic testing subsequently confirmed a diagnosis of classical galactosaemia. CONCLUSIONS: Identification of discrepancies in certain POC glucometers and capillary blood gas or venous glucose measurements by the clinical biochemistry laboratory may indicate POC glucometer interference and raise suspicion for a diagnosis of classical galactosaemia in the newborn setting.