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.
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
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.
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
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.
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
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
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.
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.
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