Study Design
This retrospective study was performed in the most southern part of Jordan (Aqaba province). Venous blood samples were collected from different hospitals in Aqaba, with a total number of 281 samples. Written informed consent was obtained from all participants, and the data were collected where it related to location, gender, age, and general health of the participants who were living in Aqaba. Exclusion criteria included subjects who showed diseases which lead to cobalamin deficiency such as peptic ulcer, gastrointestinal problem, pregnancy, diabetes, and individuals under vitamin B12 supplementation.