Calcium Deficiency/Hypocalcemia

Common in critically ill pts and may be as high as 88% in ICU pts

Neuromuscular instability leading to seizure, laryngospasm, bronchospasm, or resp arrest

Impaired cardiac function causing heart failure, hypotension, and dysrhythmias

Symptomatic hypocalcemia

Normal serum calcium content: 8.5–10.5 mg/dL.

• With 40–50% bound to plasma proteins (albumin).

• With 45–50% ionized (physiologically active).

• With 10–15% nonionized, bound to inorganic anions such as phosphate, citrate, and sulfate.

Total calcium level related to albumin level and acid-base status affects the ionized calcium level.

Ιonized calcium level is the preferred measurement (normal: 4.75–5.3 mg/dL [1.19–1.33 mol/L]).

The physiologic role of calcium:

• Neuromuscular signaling and muscle contraction.

• Hormone secretion.

• Cardiac contractility.

• Blood coagulation.

• Cell growth.

• Transport and/or secretion of fluids.