Vitamin D Deficiency and Parathyroid Response in Critically-ill Children: Association with Illness Severity and Clinical Outcomes.

ABSTRACT

Objective: To determine the prevalence of vitamin D deficiency in critically ill children, and to study its association with parathyroid response, severity of illness and clinical outcomes. Design: Prospective observational study. Setting: Medical Pediatric Intensive Care Unit of a tertiary care centre of Northern India. Participants: 154 children in-patients August 2011-January 2013. Main outcome measures: Vitamin D deficient children were (serum 25-hydroxy vitamin D <20 µg/mL) divided into "parathyroid-responder" [serum parathyroid hormone >65 pg/mL with 25(OH)D<20 µg/mL and/or calcium corrected for albumin <8.5 mg/dL] and "non parathyroid-responder.’’ Illness severity was assessed by Pediatric Index of Mortality-2 (PIM-2) score at admission. Biochemical parameters, illness severity scores and clinical outcomes were compared between parathyroid-responders and non-parathyroid-responders. Results: Vitamin D deficiency and hypocalcemia were observed in 125 (83.1%) and 91 (59%) children, respectively at admission. There were no differences in illness severity score at admission, mortality rate and length of stay between vitamin D-deficient children and 19.8% of non-vitamin D-deficient children. Among Vitamin D-deficient children, parathyroid-responders had higher PIM-2 score at admission compared to non-parathyroid-responder [12.8 (7.4,20.6) vs. 6.5 (2.5,12.2), P=0.01]. However, there were no differences in other clinical outcomes between two groups. Conclusion: Critically ill children have high prevalence of vitamin D deficiency. Parathyroid gland response secondary to hypocalcemia or vitamin D defiency is impaired in critical illness.