Magnesium, calcium and phosphorus in the intensive care unit: Do we need to monitor?

Abstract

Magnesium, calcium and phosphorus are important electrolytes involved in the regulation of homeostasis. However the utility in monitoring them in critically ill patients is still unclear. We therefore undertook a prospective, non-interventional, single center study in the intensive care unit of a tertiary care hospital in northwestern India to determine the incidence and clinical presentation of magnesium, phosphorus, and calcium abnormalities in patients admitted to the intensive care unit (ICU). Ionized calcium, serum calcium, magnesium, and phosphorus along with arterial blood gases (ABG) were measured on admission with clinical features recorded in an approved format in 300 consecutive patients admitted to the ICU over a period of two years. Thereafter, ionized calcium, serum phosphorus, serum magnesium, and ABG were monitored every alternate day. Hypocalcemia was the commonest electrolyte abnormality seen in 165 (55%) patients followed by hyperphosphatemia seen in 74 (24.67%) and hypophosphatemia seen in 72 (24%) patients. Hypocalcemia with renal failure was seen in 52 (31%) patients (P = 0.009). Hypophosphatemia and hypomagnesemia were commoner with respiratory failure i.e. 23 (31.95%) and 13 (27.66%) patients, respectively. An association of liver disease with hypomagnesemia was noted in our study, P < 0.05. Arrhythmias associated with electrolyte abnormalities were the most common clinical observation, seen in 69 (41.81%) patients with hypocalcemia, 20 (42.55%) with hypomagnesaemia, and 29 (40.27%) with hypophosphatemia. Hypocalcemia, hypomagnesemia, and hyperphosphatemia are not infrequent in patients admitted to the intensive care unit. There is a need to monitor these electrolytes to enable early detection.

Key words: Calcium; Intensive care unit; Magnesium; Phosphorus