Vitamin D is a group of fat-soluble steroids responsible for increasing intestinal absorption of calcium, iron, magnesium, phosphate and zinc. Vitamin D is mainly absorbed from food or produced through dermal synthesis in response to sunlight. It is not strictly a vitamin, and may be considered a hormone as its synthesis and activity occur in different locations. Vitamin D has a significant role in calcium homoeostasis and metabolism.
Vitamin B12 is a water-soluble vitamin that has a key role in the normal functioning of the brain and nervous system, and the formation of red blood cells. It is involved in the metabolism of every cell of the human body, especially affecting DNA synthesis, fatty acid and amino acid metabolism.
Full blood count determines general health status. It is used as a screen for a variety of disorders, such as anaemia and infection, inflammation, nutritional status and exposure to toxic substances.