**3. Studies of vitamin D specific to patients in the ICU**

There are multiple publications concerning vitamin D deficiency affecting mortality in seriously ill patients [6, 7]. Whereas these studies are prospective and controlled, the numbers of patients have not been great. In a report by Han et al. [7] high-dose vitamin D administration was studied in ventilated intensive care unit patients. This was a small pilot double-blinded randomized controlled trial. Twelve subjects were in each group. The levels were low in 43% of patients. The groups were given 50,000 vs. 1,000,000 units daily enterally vs. placebo for 5 days. High-dose vitamin D3 increased levels of 25OHD and led to decreased numbers of hospital days without any other improved clinical outcomes. The decrease in hospital length of stay not ICU days or ventilator days or hospital-acquired infections, hospital mortality, or mortality at day 84 was seen.

There are additional reports of the role of vitamin D in patients with specific major organ dysfunction. These reports have studied heart, lung, or kidney failure in the ICU. Those studies which have dealt with vitamin D supplements to assist with patients to be liberated from the ventilator because of respiratory failure have shown no benefit of supplementation to reduce time on the ventilator and speed liberation [7].

There are a considerable number of journal articles dealing with cardiac function in patients with disturbed calcium metabolism [8] and improvement of heart failure with vitamin D administration [9]. Renal failure is another common organ failure developing in seriously ill patient who requires often intensive care. There is a long tradition of vitamin D administration to dialysis patients due to their impaired renal activation of 25OH vitamin D to 1,25 dihydroxyvitamin D. New findings from a real-world study of 52,757 patients confirmed that vitamin D improves survival in hemodialysis patients [10].
