Correlation of hypocalcemia with serum parathyroid hormone and calcitonin levels in pediatric intensive care unit.

OBJECTIVES: To investigate factors involved in causing hypocalcemia in critically ill patients.

METHODS: The patients aged 1 mo to 18 y, admitted to PICU at Nemazee Hospital, from May through November 2012, were reviewed. Those with impaired calcium hemostasis or on vitamin-D supplement were excluded. Calcitonin and parathyroid hormone levels were checked if ionized calcium level was less than 3.2 mg/d. Patient's demographic data, length of stay, Pediatric Risk of Mortality-III (PRISM-III) score, the need for mechanical ventilation, inotropic drug administration and outcome were recorded.

RESULTS: Among the 294 patients enrolled in the study, the incidence of ionized hypocalcemia was 20.4 %. The mortality rate was 45 % in hypocalcemic groups and 24.8 % in normocalcemic patients. Highly significant negative correlations were found between serum ionized calcium, PRISM-III score (r = -0.371, P = 0.004), and calcitonin level (r = -0.256, P = 0.049), but no significant correlation between hypocalcemia and parathyroid hormone level (P = 0.206) was found. A significant difference was observed between survivor and non-survivor groups regarding PRISM-III score (P = 0.00), ionized calcium (P = 0.00), and calcitonin (P = 0.022) but not parathyroid hormone level (P = 0.206).

CONCLUSIONS: Hypocalcemia was associated with increased mortality rate in PICU patients. A negative correlation was found between ionized calcium level and calcitonin. There was also a link between PTH level and severity of illness. It can therefore be concluded that evaluating serum ionized calcium, calcitonin, and PTH levels can be used as prognostic factors in critically ill patients.