[Severe lactic acidosis requiring continuos haemodiafiltration in a young patient with unrecognized metabolic abnormality. Case report].

Background: Lactic acidosis (LA) is the most common form of metabolic acidosis, defined by lactate values greater than 5 mmol/L and pH<7.34. The pathogenesis of LA involves hypoxic causes (type A) and non-hypoxic (type B), often coexisting. Identification and removal of the trigger are mandatory in the therapeutic management of LA. The case: A 38 years-old male patient entered the Emergency Ward for dyspnea, fever, vomiting and hyporexia. An important respiratory distress with hyperventilation due to severe LA was found, together with severe hypoglicemia, without renal impairment. Past medical history unremarkable, except for reported episodic hypoglicemia in the childhood, with fructose "intolerance", without any other data. No evidence of intoxications, septic shock or significant cytolysis. No drugs causing LA. The patient underwent orotracheal intubation, glucose infusion, and continuous haemodiafiltration for 36-hrs. A rapid general improvement was obtained with stabilization of acid-base balance. A diagnosis of fructose-1,6-diphosphatase deficiency was made. It is an autosomical recessive gluconeogenesis abnormality, with recurrent episodes of hypoglicemia and lactic acidosis after fasting, potentially lethal. The therapy is based on avoiding prolonged fasts, glucose infusion, and a specific diet, rich in glucose without fructose intake.

Conclusions: The presence of not-otherwise-explained lactic acidosis in young patients has to place the suspect of an underlying and unknown metabolic derangement; in these cases, the involvement of the nephrologist appears to be pivotal for the differential diagnosis of the abnormalities of the acid-base balance, and for setting the best treatment.