ADVIA Centaur Active-B12 Testi

Vitamin B12 deficiency is an increasing global health concern. Although general prevalence is difficult to determine, the World Health Organization (WHO) estimates that clinical and subclinical B12 deficiency affects millions of individuals of all ages1.Estimation of prevalence is challenging due to differing opinions on criteria for deficiency, but may be as high as 10 – 15% in those over age 65, 31% in post-gastric surgery patients, 41% of long-term care residents, and 6 – 30% of patients taking metformin. Prevalence of subclinical deficiency may also be increasing in the general population due to increased use of proton-pump inhibitors.1-3

Common tests for vitamin B12 deficiency measure total vitamin B12, which is found in blood bound to two carrier proteins; approximately 70–90% is bound to haptocorrin and available only to specific cells in the small intestine; 10–30% is bound by transcobalamin. When B12 is bound to transcobalamin it is referred to as holotranscobalamin (holoTC). Only B12 in this form is available to other tissues for physiologic use1,4. Because this small fraction is the only form that is bioavailable it is also referred to as active-B12.

The ADVIA Centaur® Active-B12 (AB12)* assay from Siemens Healthcare measures holoTC in the blood, resulting in improved accuracy, sensitivity, and specificity of B12 status. This makes active-B12 a useful marker of early vitamin B12 deficiency.

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Assay Specifications

Sample Type

Serum

Sample Volume

50µL

Assay Range

5.0–146.0 pmol/L

Detection Capability

LOD: 1.08 pmol/L
LOB: 0.74 pmol/L
LOQ: 5.00 pmol/L

Calibration Interval

44 days

Onboard Stability

60 days

Time to First Result

47 min

Understanding Vit B12 Deficiency

Vitamin B12 is a water-soluble vitamin that can only be taken in from food or supplements. After the body uses these vitamins, leftover amounts leave the body through the urine. The body stores vitamin B12 in the liver, where it can remain for years. Vitamin B12 is important for the metabolism of protein, the formation of red blood cells, and the maintenance of the central nervous system.1

Vitamin B12 deficiency can occur when not enough vitamin B12 is absorbed from the gastrointestinal tract or when there is not enough dietary intake of the vitamin. Persons who follow a vegetarian or vegan diet tend to not consume enough vitamin B12.2 Vitamin B12 deficiency can lead to macrocytic anemia, nerve damage, memory loss, and psychiatric abnormalities.2

What are the signs and symptoms of vitamin B12 deficiency?1,3

Vitamin B12 deficiency associated signs and symptoms could take years to manifest in adults. Infants and children will show signs of deficiency much sooner because they have not yet had time to store sufficient amounts. People with vitamin B12 deficiency may encounter symptoms such as:

  • Anemia
  • Fatigue
  • Weakness and light-headedness
  • Shortness of breath
  • Loss of balance
  • Yellowed skin
  • Strange sensations, numbness, or tingling in the hands, legs, or feet

Who is likely to develop vitamin B12 deficiency?

  • The elderly
  • People with intestinal and/or digestive disorders
  • Heavy alcohol drinkers
  • Pregnant women.
  • Vegetarians and Vegans

Dietary Reference Intakes for vitamin B12:4
Infants (adequate intake)
0 to 6 months: 0.4 micrograms per day (mcg/day)
7 to 12 months: 0.5 mcg/day

Children
1 to 3 years: 0.9 mcg/day
4 to 8 years: 1.2 mcg/day
9 to 13 years: 1.8 mcg/day

Adolescents and Adults
Males and females age 14 and older: 2.4 mcg/day
Pregnant teens and women: 2.6 mcg/day
Breastfeeding teens and women: 2.8 mcg/day

References:
1. https://www.nlm.nih.gov/medlineplus/ency/article/002403.htm
2. https://labtestsonline.org/understanding/conditions/vitaminb12/
3. http://www.health.harvard.edu/blog/vitamin-b12-deficiency-can-be-sneaky-harmful-201301105780
4. http://www.ncbi.nlm.nih.gov/books/NBK114302/