Short-Term Biochemical and Inflammatory Responses to 10,000 versus 50,000 IU/day Cholecalciferol in Critically Ill Adults with Low Vitamin D Status: A Prospective Quasi-Experimental Study

Abstract

Low vitamin D status is common in critically ill patients, but short-term biochemical and inflammatory responses to different supplementation regimens remain uncertain. This prospective, non-randomized, quasi-experimental pretest-posttest study included 43 adult ICU patients with serum 25-hydroxyvitamin D [25(OH)D] concentrations <30 ng/mL. Participants were stratified by baseline vitamin D status and received cholecalciferol 10,000 or 50,000 IU/day for three consecutive days. Serum 25(OH)D, total lymphocyte count (TLC), neutrophil-to-lymphocyte ratio (NLR), C-reactive protein (CRP), white blood cell count (WBC), albumin, prognostic nutritional index (PNI), and total calcium were assessed at baseline and on day 4. Serum 25(OH)D increased significantly in all four groups, and the magnitude of change differed across groups (p=0.002). The largest median increase occurred in vitamin D-deficient patients receiving 50,000 IU/day; post-hoc differences were significant compared with deficient patients receiving 10,000 IU/day (p=0.002) and insufficient patients receiving 10,000 IU/day (p=0.003). CRP decreased significantly in all groups, while WBC decreased significantly in three groups, although between-group changes were not significant. TLC, NLR, albumin, PNI, and total calcium showed no significant between-group differences in change. Three-day cholecalciferol supplementation was associated with rapid increases in 25(OH)D, particularly with 50,000 IU/day in deficient patients, whereas inflammatory and nutritional-immunological responses were less consistent.