A patient with the inability to maintain in vivo levels of bound cobalamin (Cbl) and manifestations of tissue deficiency of Cbl

✍ Scribed by James A. Begley; Peter T. Burkart; Dr. Charles A. Hall

• Publisher: John Wiley and Sons
• Year: 1986
• Tongue: English
• Weight: 610 KB
• Volume: 22
• Category: Article
• ISSN: 0361-8609
• DOI: 10.1002/ajh.2830220111

✦ Synopsis

A 39-year-old woman presented with mild anemia, glossitis, an increased MCV, a low serum cobalamin (Cbl) (vitamin BIZ), mild tissue deficiency of Cbl, but with neither malabsorption of Cbl, impaired intake, nor deficiency of or inactivity of transcobalamin I1 (TC 11). Because of a persistently low holo-TC I1 (TC I1 carrying Cbl as the (circulating complex of TC 11-Cbl), much of the evaluation was focused on the patient's TC 11. Her TC I1 promoted the uptake of Cbl, reacted with anti-TC 11, and bound Cbl in vitro. A test dose of 200 wg of cyanocobalamin (CN-Cbl) i.m. increased her holo TC I1 to levels higher than those in healthy persons, but with a much more abrupt fall to a subnormal level. Two milligrams of CN-Cbl i.m. followed by 100 pg i.m. monthly failed to maintain normal amounts of circulating TC 11-Cbl or to overcome the tissue deficiency of Cbl. One milligram i.m. weekly or daily p.0. corrected both. The low holo TC I1 was considered to be responsible for the clinical expression and may have been primary to the reduced amounts of total and holo R binder of Cbl in the circulation. This study of a newly recognized defect points out the need far circulating holo TC 11, a rational use of pharmacologic amounts of Cbl, and a possible interrelationship between TC I1 and the R binder of Cbl.