This Article  • References  • Full text PDF  • Send to a friend  • Save in My Folder  • Save to citation manager  • Permissions  Citing Articles  • Citation map  • Citing articles on HighWire  • Contact me when this article is cited  Related Content  • Similar articles in JAMA  Social Bookmarking   What's this?

A Clinically Benign Cause of Cobalamin Pseudodeficiency

Ralph Carmel, MD

JAMA. 1983;250(14):1886-1890.

Abstract
A patient with R-binder deficiency lacked this cobalamin-binding protein in serum, saliva, gastric juice, and leukocytes, as demonstrated by cobalamin-binding ability and radioimmunoassay. The patient's condition was first detected because of a low serum cobalamin (vitamin B₁₂) level. His level of serum cobalamin, however, which was carried largely by transcobalamin II, was not as decreased as in the initial cases reported and was higher by some assays than by others. The demonstration of normal bone marrow morphological appearance and deoxyuridine suppression test findings, lack of attributable neurological dysfunction, and absence of methylmalonic aciduria make clear that deficiency of R binder, whose function is unknown, did not produce notable disturbance of cobalamin metabolism. This entity is probably not as rare as originally thought. It must be considered in the differential diagnosis of low serum cobalamin levels, even among elderly patients, whose conditions often tend to be automatically diagnosed as pernicious anemia.

(JAMA 1983;250:1886-1890)

Author Affiliations
From the Department of Medicine, University of Southern California School of Medicine and Los Angeles County-University of Southern California Medical Center, Los Angeles.

Footnotes
Reprint requests to USC School of Medicine, 2025 Zonal Ave, Los Angeles, CA 90033 (Dr Carmel).

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter     What's this?

THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES

An update on cobalamin deficiency in adults
Dali-Youcef and Andres
QJM 2009;102:17-28.
ABSTRACT | FULL TEXT  

Haptocorrin (Transcobalamin I) and Cobalamin Deficiencies
Carmel
Clin. Chem. 2007;53:367-368.
FULL TEXT  

Effect of Vitamin B12 Treatment on Haptocorrin
Morkbak et al.
Clin. Chem. 2006;52:1104-1111.
ABSTRACT | FULL TEXT  

Screening for Serum Total Homocysteine in Newborn Children
Refsum et al.
Clin. Chem. 2004;50:1769-1784.
ABSTRACT | FULL TEXT  

Mild Transcobalamin I (Haptocorrin) Deficiency and Low Serum Cobalamin Concentrations
Carmel
Clin. Chem. 2003;49:1367-1374.
ABSTRACT | FULL TEXT  

Holo-Transcobalamin Is an Early Marker of Changes in Cobalamin Homeostasis. A Randomized Placebo-controlled Study
Nexo et al.
Clin. Chem. 2002;48:1768-1771.
ABSTRACT | FULL TEXT  

Cobalamin Deficiency in General Practice. Assessment of the Diagnostic Utility and Cost-Benefit Analysis of Methylmalonic Acid Determination in Relation to Current Diagnostic Strategies
Holleland et al.
Clin. Chem. 1999;45:189-198.
ABSTRACT | FULL TEXT  

The Deoxyuridine Suppression Test Identifies Subtle Cobalamin Deficiency in Patients Without Typical Megaloblastic Anemia
Carmel and Karnaze
JAMA 1985;253:1284-1287.
ABSTRACT