A client is taking lithium for bipolar disorder. The client reports nausea, vomiting, diarrhea, coarse hand tremors, and confusion. What does the nurse suspect?

LITHIUM TOXICITY: Lithium has a NARROW THERAPEUTIC RANGE (0.6-1.2 mEq/L) — toxicity can occur even slightly above range. EARLY TOXICITY (1.5-2.0 mEq/L): Nausea, vomiting, diarrhea, fine tremor worsening, drowsiness, muscle weakness; MODERATE-SEVERE (2.0-2.5+): COARSE tremors, confusion, ataxia, slurred speech, hyperreflexia, seizures; SEVERE (>2.5): Seizures, coma, cardiac dysrhythmias, death; NURSING ACTION: Hold the lithium; check serum lithium level; notify the provider; the toxic client's symptoms in this question (coarse tremor, confusion, GI symptoms) indicate moderate toxicity; TOXICITY RISK FACTORS: Dehydration, sodium depletion (low sodium increases lithium retention), renal impairment, diuretics, NSAIDs, drug interactions; PATIENT EDUCATION: Maintain consistent sodium and fluid intake; don't change diet drastically; regular lithium level monitoring; report toxicity signs; stay hydrated, especially in hot weather or illness; THERAPEUTIC LEVELS: Acute mania may target 1.0-1.5; maintenance 0.6-1.0; nursing role: monitor levels, recognize toxicity, hold and notify, educate on prevention.