Blood Journal
Leading the way in experimental and clinical research in hematology


  1. GEORGE B. JERZY GLASS, M.D., Professor of Medicine and Chief,
  2. HELEN R. SKEGGS, Research Associate, and
  3. DUK HO LEE, M.D., Former Research Fellow
  1. Department of Medicine, New York Medical College—Metropolitan Medical Center, New York, New York, and Merck Sharp and Dohme Research Laboratories, West Point, Pa.
  2. Section of Gastroenterology, New York Medical Colleg
  3. Merck, Sharp and Dohme Research Laboratories, Westport
  4. Gastroenterology Research Laboratory, New York Medical College.


Administration of 6 intramuscular injections of 1000 µg. hydroxocobalamin every other day for 10 days enabled 15 individuals with initial vitamin B12 serum levels of 81 to 242 (mean 185 ± 44 µµg./ ml.) to maintain vitamin B12 concentration of the blood 6 months later at levels exceeding 3 times the pretreatment values. In 12 of these individuals who were studied for at least a 10-month period, vitamin B12 concentration in the serum 10 months after conclusion of injections was still double the initial pretreatment levels. This difference was highly significant statistically (p = 0.001). Of 11 patients followed for 15 months after conclusion of injections, in 7 the serum levels were still higher than before treatment.

No comparable results were ever reported with cyanocobalamin therapy.

  • Submitted March 9, 1965.
  • Accepted April 9, 1965.