Diagnostic method for cobalamin deficiency

Abstract

A method of diagnosing cobalamin deficiency in warm-blooded animals is described. In one embodiment, this method comprises the measurement of methylmalonic acid levels in cerebral spinal fluid to determine if such levels exceed normal range. A finding of elevated levels indicates a cobalamin deficiency. In another embodiment, the method comprises the measurement of methylmalonic acid levels in cerebral spinal fluid and serum. A finding that the ratio of methylmalonic acid in cerebral spinal fluid to that in serum is above normal is indicative of a cobalamin deficiency. Additionally, a method for assessing the effectiveness of cobalamin therapy is described. The effectiveness of therapy is assessed by determining whether cerebral spinal fluid levels of methylmalonic acid have returned to normal, or by determining whether the ratio of methylmalonic acid in cerebral spinal fluid to that in serum has returned to normal range. A method for distinguishing cobalamin deficiency from renal failure in warm-blooded animals having excessive serum MMA levels is also described. This method comprises determining the ratio of CSF MMA to serum MMA. A finding that the CSF MMA/serum MMA ratio is above normal or elevated is indicative of the presence of Cbl deficiency, whereas a finding that the CSF MMA/serum MMA ratio is below normal is indicative of renal failure.