Cbl - Cobalamin (vitamin B12) an essential nutrient manufactured only by certain microorganisms and contained only in foods of animal origin.
5-deoxyadenosyl cobalamin - a form of the vitamin with coenzyme activity
Me-cobalamin - methyl cobalamin, a form of the vitamin with coenzyme activity.
CN-Cobalamin - cyanocobalamin, commercially available form of vitamin B12.
OH-Cobalamin - Hydroxycobalamin, commercially available form of vitamin B12.
IF - Intrinsic Factor, a glycoprotein secreted in the stomach necessary for the absorption of normal levels of vitamin B12. A failure of secretion of IF leads to vitamin B12 deficiency and the condition of pernicious anaemia.
TC - transcobalamin, the transport protein required for the cellular uptake of Cbl into most tissues and carrying the minor fraction of serum Cbl.
HoloTC - holotranscobalamin, TC with Cbl bound.
HC-haptocorrin, the first CBP encountered in saliva or gastric juice. Most Cbl in serum is bound to HC; despite this genetic absence is benign.
HoloHC-holohaptocorrin, HC with Cbl bound.
Cobalamin Binding Proteins (CBP) - the nomenclature can be quite confusing,the suggested terminology for CBPs is as follows (from Markle HV, Crit Rev Clin Lab Sci, 1996;33,247-356).

SAM-S-adenosyl methionine, important in mammalian biochemistry as a methyl donor.
Methionine synthase- the enzyme responsible for the methylation of homocysteine to methionine. This enzyme requires both methylcobalamin and 5-methyl-tetrahydrofolate.
(t)Hcy- (total)homocysteine, increased in deficiencies of B12, folate and B6 (pyridoxine).
dUST-deoxyuridine suppression test, this test is a sensitive indicator that megaloblastosis is the result of impaired thymidine synthesis due to insufficient folate or Cbl. Bone marrow is cultured in the presence of 3H-thymidine. It is an expensive and time consuming test.
MCV- mean cell (or corpuscular) volume, a measure of the size of the red blood cell. A raised MCV is not unique to megaloblastic anaemia (MA) and is frequently found in other conditions unrelated to Cbl or folate deficiency.
PBAT- protein bound absorption test, designed to demonstrate that whilst the patient may be able to absorb free B12 food cannot be processed sufficiently. The diagnostic accuracy of this test has not been confirmed and standardisation is an issue.
Schilling test- a test designed for the purpose of diagnosing pernicious anemia.
PA-Pernicious anaemia, a form of anaemia resulting from deficiency of vitamin B12. This in turn results either from a failure to produce intrinsic factor or from dietary deficiency of the enzyme. PA is characterised by defective production of red blood cells and the presence of megaloblasts in the bone marrow.
Megaloblasts- An abnormal form of any of the cells that are precursors of red blood cells.
MA-megaloblastic anaemia. Anaemia due to deficiency of vitamin B12 or folic acid.
Folic acid- a vitamin that is important in the synthesis of nucleic acids. The metabolic role of folic acid id interdependent with that of vitamin B12 (both are required by rapidly dividing cells) and a deficiency of one may lead to deficiency of the other. Good sources are liver and green leaf vegetables.

News

Coming Soon !  The full video recording of the Euromedlab 2007 Active B12 workshop will be available in the next few weeks, register for your copy.

Live CME Web Conference on vitamin B12 deficiency, Prof. Ralph Green, Dec 13th 2007, register now.

read more »

Meetings

8-11 December, 2007
American Society of Hematology, Atlanta, booth 544
read more »