In premature infants with low vitamin D levels, both a daily oral dose of 1,000 IU and a single injection of 15,000 IU raise vitamin D levels to a sufficient range within 15 days without altering...
Mechanism
Synthesis from 1 study
Whether given as a pill or a shot, vitamin D3 gets turned into the same active form in the liver, which then builds up in the blood to fix the deficiency. This process doesn't touch calcium, phosphorus, or bone enzymes, so no harmful changes happen.
Most probable mechanism
Vitamin D3 from either a pill or a shot enters the bloodstream, travels to the liver, and gets converted into a form called 25-hydroxyvitamin D, which builds up in the blood until it reaches a level high enough to correct deficiency without affecting calcium, phosphorus, or bone enzymes.
Vitamin D3 is absorbed from the gastrointestinal tract after oral administration or from muscle tissue after intramuscular injection
Vitamin D3 is transported via the bloodstream to the liver
In the liver, vitamin D3 is hydroxylated by the enzyme 25-hydroxylase to form 25-hydroxyvitamin D3
Serum concentrations of 25-hydroxyvitamin D3 rise above 30 ng/mL, correcting vitamin D deficiency
No acute changes occur in serum calcium, phosphorus, or alkaline phosphatase levels because 25-hydroxyvitamin D3 does not directly stimulate intestinal calcium absorption or bone resorption at these concentrations
Evidence from Studies
Supporting (1)
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Contradicting (0)
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