What happens to your vitamin D stores if you end up in the ICU with multiple fractures and a lacerated liver after a car accident? Will your body have enough vitamin D to control inflammation, hasten healing, and prevent or fight infection?
No one knows for sure, but Assistant Professor Sadeq Quraishi (a Vitamin D Council Board member) and Professor Carlos Camargo, both of Harvard Medical School, recently summarized current thinking on the matter.
Most studies have shown that following acute stress, such as an operation, 25(OH)D levels fall up to 30%. Why, where is it going? According to Dr. Quraishi, levels fall for one or more of several reasons.
- The blood is diluted with fluid, such as IV fluids, causing vitamin D levels to fall.
- Fluid comes out of the space between cells, also diluting the blood.
- Levels of vitamin D binding protein and albumin, both of which bind and transport vitamin D, fall during acute stress.
- The kidneys waste vitamin D when under acute stress.
- Damaged and healing tissues use up more vitamin D than do healthy tissues.
So what does this mean? First, measuring blood levels of 25(OH)D in the ICU may not give accurate results due to the above factors. In fact, 25(OH)D levels may vary by the hour after major physical stress, such as major surgery or a car accident. Second, only .03% of 25(OH)D is free in the blood, the rest is bound to protein. So measuring free 25(OH)D levels may be more useful than measuring total levels.
This is crucial to understand, as at least two studies quoted by Dr. Quraishi show that death from either pneumonia or an ICU stay is up to 8 times higher in those with levels less than 20 ng/ml. In fact, one study showed that death from pneumonia in the elderly was 13 times more likely in those with very low vitamin D levels. Overall, the clear majority of studies show that your ICU stay, and I hope you don’t need one, is improved with higher vitamin D levels.