Immunity
Essential for producing and maintaining immune cells, and a deficiency can lead to decreased lymphocyte counts and impaired immune response. [Tamura, 1999][Maggini, 2007]
Holotranscobalamin
What is Holotranscobalamin?
Holotranscobalamin represents the fraction of vitamin B12 that is bound to transcobalamin, which is the transport protein that delivers B12 to cells. HoloTC is the biologically active form of B12 available for cellular uptake and use. Measuring holoTC provides a more specific indicator of the bioavailable B12 that is ready for cellular absorption and is considered a more sensitive marker for early B12 deficiency detection. This test is particularly useful in situations where the total B12 test results are ambiguous or when an early or mild B12 deficiency is suspected.
Vitamin B12, or cobalamin, is crucial for red blood cell formation, nerve function, and DNA synthesis. It's vital for maintaining healthy nerve cells and the myelin sheath, and it contributes to metabolism, fatty acid synthesis, and energy production. Holotranscobalamin (holoTC), the active part of B12, indicates bioavailability for cellular use. B12 deficiency can cause megaloblastic anemia, characterized by large, immature red blood cells, leading to fatigue and weakness. It can also lead to neurological issues like numbness, confusion, and poor memory. Insufficient B12 can stem from inadequate dietary intake, malabsorption disorders, or certain medications.
B12 absorption and utilization are affected by several factors. Folate deficiency can lead to functional B12 deficiency, while high folate levels can mask B12 deficiency symptoms. The intrinsic factor, produced in the stomach, is essential for B12 absorption, and its deficiency can lead to malabsorption later on in the small intestine. Conditions affecting intrinsic factor production, such as pernicious anemia or gastric surgery, can lead to B12 malabsorption and deficiency. In such cases, alternate ways of B12 intake, such as subcutaneous injections, may be necessary to avoid deficiency. Reduced gastric acid production, as in the elderly or from certain medications, can impair B12 absorption. H. pylori infection and chronic alcohol consumption can also reduce B12 levels.
B12 toxicity is rare, as it is water-soluble, and the body typically excretes excess amounts. High B12 levels might indicate liver disease, certain leukemias, or diabetes. For most people, managing B12 involves dietary intake or supplements, particularly for vegetarians, vegans, and those at risk of deficiency. In cases of malabsorption, B12 injections or high-dose oral supplements may be necessary.
To maintain healthy Vitamin B12 levels:
Consume a balanced diet that includes B12-rich foods such as meat, fish, poultry, eggs, and dairy products. Vegetarians and vegans may need to rely on fortified foods or B12 supplements to ensure adequate intake.
If you have a malabsorption disorder or are at risk of B12 deficiency due to factors such as age, gastric surgery, or certain medications, work with your healthcare provider to determine the appropriate form and dosage of B12 supplementation.
Be aware of potential interactions with other nutrients, such as folate, which can mask B12 deficiency symptoms. Ensure adequate intake of both nutrients through a balanced diet or supplementation if necessary.
If you suspect you have a B12 deficiency or experience symptoms like fatigue, weakness, or neurological issues, consult your healthcare provider for proper diagnosis and treatment.
Avoid excessive alcohol consumption as these factors can contribute to reduced B12 levels.
Measurement Units
Holotranscobalamin can be measured in: ng/L, pg/100mL, pg/dL, pg/L, pg/mL, pg%, pmol/L
Reference Ranges by Age and Gender
Reference ranges represent typical values for healthy individuals. Your healthcare provider must interpret your specific results.
| Age Range | Gender | Unit | Optimal | Normal | Source |
|---|---|---|---|---|---|
| All ages | All genders | pmol/L | - | 40 - 200 | Hoffmann-Lücke, 2011 |
Health Impact
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Related Biomarkers
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Vitamin B9 (Folate) in Plasma (Coming Soon)Folate and vitamin B12 have a synergistic relationship, particularly in DNA synthesis and repair, and the metabolism of homocysteine. They depend on each other to and deficiency in either vitamin can lead to megaloblastic anemia and elevated homocysteine levels, increasing the risk of cardiovascular disease.[Scott, 1999][Stabler, 2013]
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Vitamin B9 (Folate) in RBC
Folate and vitamin B12 have a synergistic relationship, particularly in DNA synthesis and repair, and the metabolism of homocysteine. They depend on each other to and deficiency in either vitamin can lead to megaloblastic anemia and elevated homocysteine levels, increasing the risk of cardiovascular disease.[Scott, 1999][Stabler, 2013]
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Academic References
- Kröger M, Mayer G, and Meier-Ewert K. Effects of vitamin B12 on performance and circadian rhythm in normal subjects (1996). Neuropsychopharmacology. DOI: 10.1016/S0893-133X(96)00055-3
- Khattak N.N., Khan M.S., and Nawaz A.. Deficiency of vitamin B12 and its relation with neurological disorders: a critical review (2020). The Journal of Basic and Applied Zoology. DOI: 10.1186/s41936-020-00148-0
- Ames D, Carne R, Mander A, Moore E, Sanders K, and Watters D. Cognitive impairment and vitamin B12: a review (2012). Int Psychogeriatr. DOI: 10.1017/S1041610211002511
- Heiner-Fokkema MR, van der Klauw MM, Wolffenbuttel BH, and Wouters HJCM. The Many Faces of Cobalamin (Vitamin B12) Deficiency (2019). Mayo Clin Proc Innov Qual Outcomes. DOI: 10.1016/j.mayocpiqo.2019.03.002
- Scott J.M.. Folate and vitamin B12 (1999). Proceedings of the Nutrition Society. DOI: 10.1017/s0029665199000580
- Hoffmann-Lücke E and Nexø E.. Holotranscobalamin a marker of vitamin B-12 status: analytical aspects and clinical utility (2011). Am J Clin Nutr. DOI: 10.3945/ajcn.111.013458
- Selhub J. Homocysteine metabolism (1999). Annu Rev Nutr.. DOI: 10.1146/annurev.nutr.19.1.217
- Refsum H. and Smith A. D.. Homocysteine, B Vitamins, and Cognitive Impairment (2016). Annual Review of Nutrition. DOI: 10.1146/annurev-nutr-071715-050947
- Clarke R., McPartlin J., Nexø E., Scott J.M., Smith A. D., and Ueland P. M.. Facts and recommendations about total homocysteine determinations: an expert opinion (2006). Clinical Chemistry. DOI: 10.1373/clinchem.2003.021634
- Beydoun HA, Beydoun MA, Canas JA, Gamaldo AA, McNeely JM, Shah MT, and Zonderman AB. Serum nutritional biomarkers and their associations with sleep among US adults in recent national surveys (2014). PLoS One. DOI: 10.1371/journal.pone.0103490
- Mariën P, Clement F, De Deyn PP, Engelborghs S, Goeman J, Ketels V, Maertens K, Pickut BA, Saerens J, Somers N, Symons A, Vandevivere J, and Vloeberghs E. Correlations between cognitive behavioural and psychological findings and levels of vitamin B12 and folate in patients with dementia (2004). Int J Geriatr Psychiatry. DOI: 10.1002/gps.1092
- Stabler S.P.. Vitamin B12 deficiency (2013). New England Journal of Medicine. DOI: 10.1056/NEJMcp1113996
- Green R, Owen PJ, Ward M, and Wolffenbuttel BH. Vitamin B12 (2023). BMJ. DOI: 10.1136/bmj-2022-071725
- Köbe Theresa, Bohlken J, Flöel A, Grittner U, Hahn A, Pantel J, Rujescu D, Schnelle A, Schuchardt JP, Tesky VA, and Witte AV. Vitamin B-12 concentration memory performance and hippocampal structure in patients with mild cognitive impairment (2016). Am J Clin Nutr. DOI: 10.3945/ajcn.115.116970
- Morris MS. The role of B vitamins in preventing and treating cognitive impairment and decline (2012). Adv Nutr. DOI: 10.3945/an.112.002535
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