Unexplained low serum vitamin B|2 (Br) concentrations have been reported in multiple myeloma (MM), with or without associated clinical manifestations of B r deficiency. Raised serum levels of methylmalonic acid (MMA) are a sensitive and specific marker for biochemical B|; deficiency in the absence of significant renal impairment. We defined biochemical evidence of presumed Bp deficiency as a finding of serum MMA above the normal reference range (mean ±3SD) with or without raised total homocysteine (tHCY) in the absence of significant renal disease (creatinine <2.0 mg/dl). Five of 42 patients with MM had serum Br below normal (<170 pg/ml). Three of these had raised MMA and tHCY; one had raised MMA alone. None had serum creatinine >2.0 mg/dl. In a further six patients with normal serum Bp, two had raised MMA and tHCY and four had raised MMA alone. All had serum creatinine <2.0 mg/dl. The occurrence of presumed B |2 deficiency observed in a high proportion of our patients with MM (11 of 42 or 26% with raised metabolites not explained by significant renal impairment) may be the result of increased B]2 requirements in this condition. Increased uptake and accumulation of Bp has been reported in myeloma cells in culture (Ermens A. et al. Eur.J.Haematol 50:57,1993). B|2 administration to patients with MM may accelerate tumor growth (Schleinitz N, et al. Leuk.Res. 22:287, 1998) and supplements of this vitamin may, therefore, be contraindicated in patients with clonal plasma cell dyscrasias. It is possible that analogues or inhibitors of Bp may prove useful in the management of MM.
|Original language||English (US)|
|Issue number||11 PART II|
|State||Published - 2000|
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