Atellica IM/ADVIA Centaur Active-B12 Assay

Atellica IM/ADVIA Centaur Active-B12 Assay
 
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Vitamin B12 (cobalamin) plays an important role in DNA syntesis and neurologic function. Deficiency can lead to a wide spectrum of hematologic and neuropsychiatric disorders that can often be reserved by early diagnosis and prompt treatment.1

The primary analysis of vitamin B12 deficiency is the measurement of serum cobalamin (vitamin B12).2 There commonly used tests measure total vitamin B12, which is found in blood bound to two carrier poteins: haptocorrin and transcobalamin. When vitamin B12 is bound to transcobalamin it is referred to as holotranscobalamin (holoTC). HoloTC contains the biologically available cobalamin as only holoTC promotes the uptake of cobalamin by all cells via specific receptors. In comparison, approximately 80% of the circulating cobalamin that is carried by haptocorrin is considered metabolically inert because no cellular receptors exist (with the exception of receptors found in the liver.)3

The Siemens Healthineers Active-B12 (AB12) assay offered on the Atellica® IM Analyzer and ADVIA Centaur® Immunoassay Systems measures holo TC in the blood – the only form of vitamin B12 that is taken up and used by cells of the body.

Assay Specifications

ADVIA Centaur Active-B12 Assay

 Atellica IMADVIA Centaur XP/XPTADVIA Centaur CP
Sample TypeSerumSerumSerum
Sample Volume50µL50 µL50 µL
Assay Range4.25-146.00 pmol/L5.00 – 146.00 pmol/L5.00 – 146.00 pmol/L
Detection CapabilityLoB: 0.46 pmol/L
LoD: 0.83 pmol/L
LoQ: 4.25 pmol/L

LoB: 0.52 pmol/L
LoD: 1.19 pmol/L
LoQ: 5.00 pmol/L

LoB: 2.73 pmol/L
LoD: 2.99 pmol/L
LoQ: 5.00 pmol/L

Calibration IntervalLot: 28 days
Pack: 28 days
44 days30 days
Onboard Stability28 days44 days38 days
Time to First Result38 min47 min42 min

 

Understanding Vit B12 Deficiency

The most common causes of megaloblastic anemia are deficiency of either cobalamin (vitamin B12) or folate (vitamin B9). Your body needs folate and vitamin B12 to produce enough healthy red blood cells. A diet lacking in these and other key nutrients can cause decreased red blood cell production. Additionally, some people may consume enough vitamin B12, but their bodies aren't able to process the vitamin. This can lead to vitamin deficiency anemia, also known as pernicious anemia.

  • A deficiency in vitamin B12 can result in varying degrees of neuropathy or nerve damage. In severe cases, mental changes that range from confusion and irritability to dementia may occur4.
  • Pregnant women need increased folate for proper fetal development because of the added stress of rapidly growing fetal cells. A folate deficiency during pregnancy, especially in the early weeks when a woman might not know she is pregnant, may lead to premature birth and neural tube birth defects (NTDs) such as spina bifida in the child4.

Vitamin B12 in serum is bound to two proteins: transcobalamin (TC) and haptocorrin (HC). The transcobalamin vitamin B12 complex is called holotranscobalamin (holoTC). HoloTC is also known as active-B12 as it contains the biologically available cobalamin, as only holoTC promotes the uptake of cobalamin by all cells via specific receptors. HoloTC has been shown to be superior to other relevant lab parameters in B12 deficiency, such as serum total cobalamin and methylmalonic acid (MMA), for diagnosing vitamin B12 deficiency5.

Laboratory testing is used to detect a vitamin deficiency, determine its severity, establish it as the underlying cause of someone's symptoms, and to monitor the effectiveness of treatment.4

What are the signs and symptoms of vitamin B12 deficiency?6,7
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 B12:8

Infants (adequate intake)
   0 to 6 months: 0.4 micro grams 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  


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ADVIA Centaur and all associated marks are trademarks of Siemens Healthcare Diagnostics Inc. or its affiliates.


References:
1. https://ods.od.nih.gov/factsheets/vitaminB12-HealthProfessional/.
2. Yetley EA, Pfeiffer CM, Phinney KW, et al. Biomarkers of vitamin B-12 status in NHAVES: a roundtable summary. Am J Clin Nutr 2011;94:313S-21S.
3. Siemens Helahineers ADVIA Centaur AB12 Instructions for use: RPBL1160R3_EN Rev. C, 2017-09.
4. WHO/UNICEF/UNU. Iron deficiency anemia: assessment, prevention, and control. World Health Organization Geneva. 2001; (WHO/NDH/01.3)
5. http://www.nhlbi.nih.gov/health-topics/iron-deficiency-anemia
6. http://www.nlm.nih.gov/medlineplus/ency/article/002403.htm
7. http://www.health.harvard.edu/blog/vitamin-b12-deficiency-can-be-sneaky-harmful-201301105780
8. http://www.ncbi.nlm.nih.gov/books/NBK114302/