Folate replacement therapy

If severe methotrexate toxicity occurs, reduced folate replacement therapy with 5-formyltetrahydrofolate... 

Symptoms associated with folate deficiency are similar to those seen in patients with vitamin B12 deficiency, with the absence of neurologic symptoms. Although the symptoms of anemia will improve with folate replacement and a partial hematologic response will occur, the neurologic manifestations of vitamin B12 deficiency will not be reversed with folic acid replacement therapy and consequently may become irreversible if not treated. 

Carney, M. W. P., and Sheffield, B. F., 1970, Associations of subnormal serum folate and vitamin Bj2 values and effects of replacement therapy, J. Nerv. Ment. Dis. 150 404. 

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