Foundation:

methylmalonic aciduria is one of the most frequent organic acidurias and groups together a set of genetic defects, characterized by the excretion of elevated levels of urinemethyl malonic acid. The excretion of this metabolite may or may not be accompanied by elevated homocysteine ​​levels depending on the affected metabolic pathway.

Objective:

to describe the implementation of a laboratory methodology that combines methylmalonic acid and homocysteine ​​in the differential diagnosis and monitoring of methylmalonic aciduria in the period from 2013 to 2018.

Methods:

for patients with an increase in methylmalonic acid in the organic acid profile, homocysteine ​​was quantified in plasma and urine. The identification of methylmalonic acid was performed by gas chromatography / mass spectrometry, while the homocysteine ​​quantification by high performance liquid chromatography.

Results:

chromatographic methods allowed the identification and quantification of methylmalonic acid and homocysteine, respectively. Homocysteine ​​was quantified in seven patients with increased levels of methylmalonic aciduria. Homocysteine ​​levels in four of them were higher than normal values, suggesting aciduria combined with homocystinuria. Three of the patients with combined methylmalonic aciduria under treatment showed a decrease in the levels of both metabolites, corresponding to a satisfactory evolution.

Conclusions:

simultaneous determination of both markers allowed differential diagnosis and biochemical monitoring of this disease.

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