Changes in ionized calcium in ethylene glycol poisoning

Ethylene glycol is a sweet-tasting toxic alcohol contained in a variety of chemical preparations. In patients poisoned with ethylene glycol, diagnosis is often based upon clinical suspicion and nonspecific tests. Hypocalcemia is often present due to calcium oxalate crystals formed by oxalic acid metabolite complexation. This retrospective study involved a review of clinical records of patients with a diagnosis of ethylene glycol poisoning. Results of blood gas samples, lactate, ionized calcium, and serum creatinine were documented and compared between various groups. The ionized calcium concentration was below the normal range in 59% of cases at the time of presentation and more commonly associated with a blood pH of <7.3 in 79% of cases. The number of patients with a low ionized calcium concentration increased over time. A low ionized calcium concentration was a common finding in cases of severe ethylene glycol poisoning and was more commonly associated with patients exhibiting metabolic acidosis or developing acute kidney injury or death. Ionized calcium concentration on presentation may be an additional marker in concert with blood pH that can be used in the risk assessment and stratification of severity and complications of ethylene glycol poisoning.