Hopefully by the end of this article you’ll have no doubts about this subject.
How The Test Is Performed
Many experts recommend a level between 20 and 40 ng/mL. Others recommend a level between 30 and 50 ng/mL. Normal value ranges may vary slightly among different laboratories.
The two hormones (ergo- and cholecalciferol) work similarly in the body.
Symptoms And Health Risks Of Vitamin D Deficiency
Low blood levels of the vitamin have been associated with the following: Increased risk of death from cardiovascular disease
Cognitive impairment in older adults
Severe asthma in children
Cancer Research suggests that vitamin D could play a role in the prevention and treatment of a number of different conditions, including type1 and type 2 diabetes, hypertension, glucose intolerance, and multiple sclerosi.
Reference Range
25-hydroxyvitamin D (25(OH)D) is the major circulating form of vitamin D; thus, the total serum 25(OH)D level is currently considered the best indicator of vitamin D supply to the body from cutaneous synthesis and nutritional intake.
One exception is that 25(OH)D levels do not indicate clinical vitamin D status in patients with chronic renal failure or type 1 vitamin D-dependent rickets or when calcitriol (1,25-dihydroxyvitamin D) is used as a supplement.
Historical Perspective
The association of sunlight and vitamin D for bone health began with the industrialization of northern Europe. The lack of adequate sun exposure resulted in an epidemic of children with severe growth retardation and bony deformities that was commonly known as rickets.1 In 1919, Huldschinsky et al2 reported that exposure to ultraviolet radiation cured rickets.
When 7-dehydrocholesterol was easily extracted from lanolin from sheep’s wool, vitamin D 3 was inexpensively made and was used in food fortification and for supplements. In the early 1950’s, there was an outbreak of hypercalcemia thought due to the over fortification of milk with vitamin D, and as a result, most European countries forbid the fortification of milk and other dairy products with vitamin D. In the United States, milk and orange juice are fortified with vitamin D 3 whereas a majority of multivitamin supplements and pharmaceutical preparations contain vitamin D 2 .1, 4 The appreciation that vitamin D (D represents either D 2 or D 3 ) required a hepatic hydroxylation on carbon 25 to produce 25-hydroxyvitamin D [25(OH)D] required a hepatic hydroxylation on carbon 25 to produce 25-hydroxyvitamin D [25(OH)D] ( ) led to the development of a binding protein assay using the vitamin D binding protein (DBP) to measure circulating levels of 25(OH)D in the circulation.5-7 The identification of 1,25-hydroxyvitamin D as being the biologically active form of vitamin D led to the development of a binding protein assay using the vitamin D receptor as the binder to measure circulating levels of 1,25(OH) 2 D.8-10 Open in a separate window.