Adult: 4.4 to 5.3 mg/dL; SI units: 1.05–1.3 mmol/L
Child: 4.4 to 6.0 mg/dL; SI units: 1.2–1.38 mmol/L
Critical levels: > 6.29 mg/dL; SI units: >1.57 mmol/L or <3.1
mg/dL; SI units: < 0.78 mmol/L
. Red-top tube.
■ Ionized calcium is the metabolically active form of calcium.
■ Level is affected by the albumin level, blood pH, phosphate,
magnesium, and bicarbonate levels.
■ Decreased by factors that bind calcium (citrate from
transfused blood or free fatty acids from total parenteral
nutrition [TPN]).
■ Decreased levels affect heart rhythm and neurologic status.
