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Hypocalcemia in critically ill children
N Cardenas-Rivero1, B Chernow, M A Stoiko
1Department of Pediatrics, Harvard Medical School, Boston, MA.
Insights
Ionized hypocalcemia is common in critically ill children, affecting at least 17.9% of patients. While associated with higher mortality, this may be linked to illness severity rather than calcium levels alone.
Area of Science:
- Pediatric Intensive Care
- Critical Care Medicine
- Endocrinology
Background:
- Hypocalcemia is a potential complication in critically ill children.
- Understanding calcium homeostasis is crucial for managing severe pediatric illness.
Purpose of the Study:
- To determine the prevalence of ionized hypocalcemia in pediatric intensive care unit (PICU) patients.
- To investigate the clinical consequences and potential causes of hypocalcemia in this population.
Main Methods:
- Prospective study of calcium homeostasis in 145 PICU patients.
- Measurement of total serum calcium and ionized calcium levels.
- Assessment of illness severity using the Therapeutic Intervention Scoring System (TISS) and evaluation for sepsis and hypoparathyroidism.
Main Results:
- The prevalence of ionized hypocalcemia was at least 17.9%.
- Patients with ionized hypocalcemia had a significantly higher mortality rate (31% vs 2.5%).
- Ionized hypocalcemia was associated with greater illness severity, sepsis, and vasopressor use.
Conclusions:
- Ionized hypocalcemia is prevalent in severely ill children.
- While associated with increased mortality, causality is confounded by illness severity.
- Functional hypoparathyroidism may contribute to hypocalcemia in critically ill children.
Abstract:
To determine the prevalence and clinical consequences of hypocalcemia in pediatric intensive care unit patients, we prospectively studied calcium homeostasis in 145 of these patients. The total serum calcium concentration was measured in all patients. The serum ionized calcium concentration was measured in blood samples collected from those 71 (49%) patients who had low total serum calcium values (less than 8.5 mg/dl (2.12 mmol/L). Of the 71 patients, 26 (36.6%) had ionized hypocalcemia. Therefore the prevalence of ionized hypocalcemia was at least 17.9% (26/145). Death occurred in 8 (31%) of 26 patients with ionized hypocalcemia versus 3 (2.5%) of 119 patients with normocalcemia (p less than 0.0001). However, the severity of illness score was higher (p less than 0.05) in the children with ionized hypocalcemia than in normocalcemic children (mean Therapeutic Intervention Scoring System score 33 +/- 17 vs 22 +/- 11, respectively). More of the children with ionized hypocalcemia had sepsis (p = 0.0299) and they required the administration of vasopressor agents more often (p = 0.0002) than their normocalcemic counterparts. Of the 26 patients with ionized hypocalcemia, 17 (65.4%) had biochemical evidence of either absolute or relative hypoparathyroidism, determined by means of an immunoradiometric assay that measures only biologically active parathyroid hormone. We conclude the following: (1) ionized hypocalcemia is common in severely ill children. (2) Patients with ionized hypocalcemia have a higher mortality rate than those with normocalcemia; however, because the former are more severely ill, no causality is apparent or suggested. (3) Functional hypoparathyroidism may occur in critically ill children.