[1. Oh RC, Brown DL. Vitamin B12 deficiency. Am Fam Physician. 2003 Mar;67(5):979-86.]Search in Google Scholar
[2. Wolters M, Ströhle A, Hahn A. Cobalamin: a critical vitamin in the elderly. Prev Med. 2004 Dec;39(6):1256-66. DOI: 10.1016/j.ypmed.2004.04.04710.1016/j.ypmed.2004.04.047]Search in Google Scholar
[3. Allen LH. Causes of vitamin B12 and folate deficiency.Food Nutr Bull. 2008 Jun;29(2 Suppl):S20-34.10.1177/15648265080292S105]Search in Google Scholar
[4. Halfdanarson TR, Litzow MR, Murray JA. Hematologic manifestations of celiac disease. Blood. 2007 Jan;109(2):412-21. DOI: 10.1182/ blood-2006-07-03110410.1182/blood-2006-07-031104]Search in Google Scholar
[5. Jabbar A, Yawar A, Waseem S, Islam N, Ul Haque N, Zuberi L, et al. Vitamin B12 deficiency common in primary hypothyroidism. J Pak Med Assoc. 2008May;58(5):258-61.]Search in Google Scholar
[6. Lam JR, Schneider JL, Zhao W, Corley DA. Proton pump inhibitor and histamine 2 receptor antagonist use and vitamin B12 deficiency. JAMA. 2013 Dec;310(22):2435-42. DOI: 10.1001/jama.2013.28049010.1001/jama.2013.280490]Search in Google Scholar
[7. Reinstatler L, Ping Qt Y, Williamson RS, Garn JV, Oakley Jr GP. Association of biochemical B12 deficiency with metformin therapy and vitamin B12 supplements: The national health and nutrition examination Survey, 1999-2006. Diabetes Care. 2012 Feb;35:327-33. DOI: 10.2337/dc11-158210.2337/dc11-1582]Search in Google Scholar
[8. Iqtidar N, Chaudary MN. Misdiagnosed vitamin B12 deficiency a challenge to be confronted by use of modern screening markers. J Pak Med Assoc. 2012 Nov;62(11):1223-9.]Search in Google Scholar
[9. Allen LH. How common is vitamin B-12 deficiency? Am J Clin Nutr. 2009 Feb;89(2):693S-6S. DOI: 10.3945/ajcn.2008.26947A10.3945/ajcn.2008.26947A]Search in Google Scholar
[10. Hvas AM, Nexo E. Diagnosis and treatment of vitamin B12 deficiency - an update. Haematol. 2006 Nov;91(11):1506-12.]Search in Google Scholar
[11. McLean E, de Benoist B, Allen LH. Review of the magnitude of folate and vitamin B12 deficiencies worldwide. Food Nutr Bull. 2008 Jul;29(2):S38-S51.10.1177/15648265080292S107]Search in Google Scholar
[12. Roche Diagnostics GmbH. Package inserts/method sheets.]Search in Google Scholar
[13. Heil W, Ehrhardt V. Reference Ranges for Adults and Children Pre-Analytical Considerations. Roche Diagnostics Ltd.: Switzerland, 2008, pp 72.]Search in Google Scholar
[14. Arora S, Singh B, Gupta VK, Venkatesan M. Burden of vitamin B12 deficiency in urban population in Delhi, India: a hospital based study. Int J Pharm Bio Sci. 2011 Jan-Mar;2(1):B521-28.]Search in Google Scholar
[15. Drabkin DL, Austin JH. Spectrophotometric studies: Spectrophotometric constants for common hemoglobin derivatives in human, dog and rabbit blood. J Biol Chem. 1932 Nov;98(2):719-33.10.1016/S0021-9258(18)76122-X]Search in Google Scholar
[16. Oshiro I, Takenaka T, Maeda J. New method for hemoglobin determination by using sodium lauryl sulfate (SLS). Clin Biochem. 1982 April;15(2):83-88. DOI: 10.1016/S0009-9120(82)91069-410.1016/S0009-9120(82)91069-4]Search in Google Scholar
[17. Hertzog MA. Considerations in determining sample size for pilot studies. Res Nurs Health. 2008 Apr;31(2):180-91. DOI: 10.1002/nur.2024710.1002/nur.2024718183564]Search in Google Scholar
[18. Sütterlin MW, Bussen SS, Rieger L, Dietl J, Steck T. Serum folate and Vitamin B12 levels in women using modern oral contraceptives (OC) containing 20 microgethinyl estradiol. Eur J Obstet Gynecol Reprod Biol. 2003 Mar;107(1):57-61. DOI: 10.1016/S0301-2115(02)00371-810.1016/S0301-2115(02)00371-8]Search in Google Scholar
[19. McArthur JO, Tang H, Petocz P, Samman S. Biological variability and impact of oral contraceptives on vitamins B6, B12 and folate status in women of reproductive age. Nutrients. 2013 Sep;5(9):3634-45. DOI: 10.3390/nu5093634 20. Da Silva L, McCray S. Vitamin B12: no one should be without it. Practical Gastroenterology. 2009 Jan;XXXIII(1):34-46.]Search in Google Scholar
[21. Qatatsheh A. Vitamin B12 status in males and females of different age groups. Am J Agri and Biol Sci. 2011 June;6(2):221-26. DOI: 10.3844/ajabssp.2011.221.22610.3844/ajabssp.2011.221.226]Search in Google Scholar
[22. Dharmarajan TS, Norkus EP. An algorithmic approach to the screening of vitamin B12 status and the treatment of identified deficiency. In: Herbert V. Vitamin B12 deficiency. London: Royal Society of Medicine Press Ltd, 1999:49-52.]Search in Google Scholar
[23. Stabler SP. Screening the older population for cobalamin deficiency. J Am Geriatr Soc. 1995 Nov;43(11):1290-7.10.1111/j.1532-5415.1995.tb07408.x7594166]Search in Google Scholar
[24. Mar N, Askin D, Klafter RJ. Pitfalls in the diagnosis of vitamin B12 deficiency. Open J Hematol. 2012 Sept;3(1):2. 10.13055/ojhmt_3_1_2.120920]Search in Google Scholar