Ácido metilmalônico no diagnóstico das anemias megaloblásticas

Abstract

The main causes of megaloblastic anemia are the deficiencies of vitamin B12 and/or folic acid and it is very important the differential diagnosis between these deficiencies, since the administration of folic acid to patients with vitamin B12 deficiency can correct the hematologic changes, without preventing the progression of neurological disease. The neurological manifestations of vitamin B12 deficiency can occur even when plasma levels of this vitamin are within the reference values, so that it is also very important the diagnosis of subclinical disease. The determination of parameters associated with vitamin B12, such as methylmalonic acid and homocysteine, have emerged as additional tools to improve the diagnosis of subclinical disease, and has also facilitated the realization of the differential diagnosis between vitamin B12 and folic acid. Thus, the determination of these parameters is a tool with great potential to improve the diagnosis of megaloblastic anemia in clinical laboratories. Considering the limitations related to the determination and interpretation of plasma levels of vitamin B12, the main objective of this review is to alert the professionals who deal with this issue on the importance of subclinical disease and the latest laboratory methods potentially applicable for improving the diagnosis of this condition. However, many gaps still exist regarding the proper approach and confirmation of suspected cases of vitamin B12 deficiency and/or folic acid, which undoubtedly will demand further study.