Vitamin D deficiency is a worldwide public health problem across all age groups including infants, children, adults, and elderly. Very few foods naturally contain or are fortified with vitamin D. The major source of vitamin D is from sunlight exposure. Vitamin D, the sunshine vitamin is synthesized from 7-dehydocholesterol present in the skin of humans by the action of ultraviolet B radiation (290 – 315 nm). The major cause of vitamin D deficiency is lack of adequate sunlight exposure. In utero and during childhood, vitamin D deficiency can cause growth retardation and skeletal deformities and may increase the risk of hip fracture later in life. Vitamin D deficiency in adults can precipitate or exacerbate osteopenia and osteoporosis, cause pain producing osteomalacia and muscle weakness, and increase the risk of fall and fracture. Vitamin D deficiency is associated with increased risk of common cancers, autoimmune diseases, infectious diseases, and cardiovascular mortality. Serum 25-hydroxy vitamin D (25-OHD) is the reliable marker of vitamin D status and a level below 20 ng/ml defines deficiency. However, an optimal level above 30 ng/ml is required to maximize the bone health and non-skeletal benefits of vitamin D. A sensible sun exposure for 5 – 15 min between 1000 and 1500 hours in the spring, summer and autumn and supplementation of atleast 400 IU, 600 IU and 800 IU of vitamin D/day among infants and children, adults and elderly respectively shall guarantee vitamin D sufficiency in at risk population.
Multiple sclerosis (MS) is a socially significant immune-mediated disease with unknown etiology. The first symptoms are usually registered in the reproductive age-between the 20th and 40th year, with first peak between the 21st and 25th year, and the second peak between the 41st and 45th year. In less than 5 to 10% of the cases the onset of the disease is before the 10th and the after the 50th year. Results from different studies of the disease evolution show that women suffer from it more frequently than men-ration women/ men 2:1, 3:1 [1,2,3,4,5]. The three main forms of progress of the disease: relapsing-remitting (RRMS), secondary-progressive (SPMS) andprimary-progressive (PPMS), reflect the chronic development of the process, disabling the patients for a different period of time.
This chapter deals with vitamin D and its metabolites from the point of view of the steps involved in their analytical determination. Thus, after a brief description of the characteristics and metabolism of vitamin D to introduce the target metabolites, the analytical aspects of these compounds are addressed. First, we discuss the suitability of the types of samples (e.g., fresh and dry blood, urine, saliva, cerebrospinal fluid) in which vitamin D and its metabolites are determined; then, the stability of the most used sample (blood as both serum and plasma) under different storage conditions is considered in the light of the different metabolites to be measured.
1. Nighat Yaseen Sofi
2. Anirban Mandal
3. Wesam Amiri