The nurse receives laboratory results for four clients. Which result requires immediate follow-up?

Severe hyponatremia with new neurologic symptoms can progress to seizures or impaired consciousness and needs urgent evaluation. The other abnormalities require follow-up but lack the same immediate neurologic threat in the stated context.

Quick answer
Follow up the sodium 118 mEq/L with new confusion and gait instability first. The combination suggests symptomatic severe hyponatremia and possible cerebral edema.

Why this is correct
Priority depends on both the value and the client's response. Marked hyponatremia can shift water into brain cells; new confusion and unsteady gait show neurologic involvement, so urgent assessment and treatment planning should not wait for routine rounds.

Easy analogy or mental picture
Think of the skull as a rigid container around water-sensitive wiring. When sodium falls sharply, brain cells can swell inside that fixed space; the picture explains urgency but does not predict the cause or permit overly rapid correction.

Memory hook
A dangerous value plus a new neurologic change outranks an abnormal value in a stable, asymptomatic client.

NCLEX decision rule
For laboratory-priority questions, pair the number with symptoms and instability. Severe sodium reduction with confusion, seizure, reduced consciousness, or gait change requires urgent follow-up, while correction must still be controlled to avoid neurologic injury.

Why the other choices are wrong
INR 4.2 without bleeding, chronic asymptomatic hemoglobin 8.1 g/dL, and magnesium 1.5 mg/dL with mild cramps each need timely review. None presents the same immediate cerebral risk as symptomatic sodium 118 mEq/L.