Chemotherapy-induced suppression of serum holotranscobalamin

Abstract

e20639 Purpose: Chemotherapy-induced damage to the stomach and small intestine may inhibit the absorption of vitamin B12. To assess the risk of chemotherapy causing acute vitamin B12 deficiency, we primarily measured the active form of vitamin B12, holotranscobalamin, but also total serum B12, methylmalonic acid, and total homocysteine. Experimental Design: We studied 21 patients that were actively on chemotherapy and recorded values for holotranscobalamin, total serum B12, methylmalonic acid, total homocysteine, and cystatin-c. Measurements were taken both before and after four doses of chemotherapy. T-tests were employed to determine statistical significance. Results: There was a statistically significant drop in holotranscobalamin after chemotherapy in eighteen out of twenty-one patients (p = 2.64x10–3). Three patients were vitamin B12 deficient as defined by total B12 < 300 pg/ml. Neither methylmalonic acid (p = 3.95x10–1), nor total homocysteine (p = 4.34x10–1), showed any significant changes. Conclusions: Chemotherapy caused an acute deficiency of the only metabolically active form of vitamin B12, holotranscobalamin, despite B12 supplementation. We suggest monitoring patients for changes in holotranscobalamin to ensure that prolonged deficiency does not occur. The clinical implications of acute lowering of holotranscobalamin remain unknown. No significant financial relationships to disclose.