Dr. Ebraheim’s educational animated video describes tests that orthopaedic surgeons should think about - 25 Vitamin D.

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Vitamin D 25 is the most appropriate study to assess and monitor vitamin D status in the body. Vitamin D is important for proper maturation and development of bone. Vitamin D is also important in immunity and plays a role in other conditions. The main function of Vitamin D is absorption of the calcium and phosphate from the intestine. Vitamin D comes from diet, supplements, and exposure to the sun. Vitamin D is naturally found in fish. Exposure to the sun for 15 minutes will give a person about 10,000 units of Vitamin D. The average daily requirement of Vitamin D is approximately 400-800 International Units (IUs). Vitamin D gets activated metabolically in the liver and in the kidney. The activation occurs by hydroxylation. Hydroxylation to 25 Vitamin D3 occurs in the liver. The big organ takes the big number- 25, so 25(OH)-Vitamin D3. Another hydroxylation occurs in the kidneys. The small organ takes the small number-1. The result will be 1, 25 (OH)2- Vitamin D3. This is the active form of Vitamin D and works mainly on the intestines and bones. The activation of Vitamin D to 1, 25 hydroxyvitamin D is controlled by the parathyroid hormone. Any deficiency or any problem in the process of activating Vitamin D3 to its active form will lead to deficiency of Vitamin D in the body. Vitamin D deficiency is very common and the majority of people are not aware of it. In fact, Vitamin D deficiency symptoms are subtle and nonspecific. 25-hydroxyvitamin D has a long half-life and a higher concentration. This is probably easier to measure and obtain 25 hydroxyvitamin D than the active form, which is 1,25-dihydroxyvitamin D. The half-life of 25-hydroxyvitamin D is 2-3 weeks. The half-life of 1,25-dihidroxyvitamin D is only 4-6 hours. The circulating levels of 25- hydroxyvitamin D is 1000x more than 1,25 dihydroxyvitamin D. therefore, 25-hydroxyvitamin D test is the best study to determine the Vitamin D deficiency in the body. A low level of 25- hydroxyvitamin D could mean that a person is not getting enough exposure to the sun, is not getting enough dietary Vitamin D, or there may be a problem with absorbing Vitamin D from the intestines. The patient may be taking Dilantin, which interferes with hydroxylation of Vitamin D in the liver. A low level of 1, 25-dihydroxyvitamin D usually indicates kidney disease. 40% of the United States population have Vitamin D deficiency.
Symptoms of Vitamin D deficiency may include:
• Fatigue and tiredness
• Not sleeping well
• Muscle weakness
• Bone pain
• Osteoporosis/ Osteomalacia
• Fractures
Elderly patients are vulnerable to Vitamin D deficiency because they usually live indoors or in nursing homes with no sun exposure or because these patients may not eat enough food containing Vitamin D or they may not receive enough supplements. Vitamin D deficiency may impair or affect wound healing. Vitamin D deficiency may cause bone loss and places the elderly patient at risk of fractures. Deficiency may cause slow healing of fractures or nonunion of the fractures. If you find a patient with fractures that are not healing well, or a patient with fractures due to low energy trauma where you find the bone mass is inadequate (osteoporosis), this is the time to get a 25- hydroxyvitamin D blood test. The Endocrine Society defines Vitamin D deficiency as 25 Vitamin D level below 20 ng/mL, and insufficiency as the level between 21-29 ng/mL. In general, a 25 Vitamin D level greater than 30 ng/mL is probably adequate, but these numbers are controversial.

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