Blood Sampling
Blood samples were collected from hospitals in the Aqaba governorate then serum was preserved at -70°C until use to measure the level of vitamin B12 and further study according to standard procedures using commercially available kits. Laboratory analyses were performed at hospital laboratories in Aqaba, Jordan. The level of vitamin B12 was assessed based on sandwich enzyme-linked immunosorbent assay technology, according to the manufacturer’s protocol (Cyanocobalamin (Vitamin B12) ELISA Kit, Abbexa, UK).