Question 2 of 11

A 44-year-old man complains of nausea, vomiting, diarrhea, and a wobbly gait. Vital signs: heart rate 42/min, respiratory rate 20/min, blood pressure 95/60 mm Hg. Pertinent findings include disorientation, slurred speech, muscle fasciculations, and hand tremors. His wife states that he has bipolar disease and has taken lithium for several years without problems; recently he was started on furosemide for signs of water retention. A serum lithium level is 2.6 mEq/L. An EKG shows sinus bradycardia. Serum creatinine is 2.4 mg/dL. In order to treat him appropriately, you know that:

Intravenous normal saline and a loop diuretic will help promote lithium diuresis.

Alkalinization of urine with intravenous bicarbonate will significantly lower his lithium level.

Activated charcoal effectively adsorbs lithium.

Intravascular fluid replacement with normal saline and hemodialysis are indicated for this patient.

The most common significant cardiac dysfunction in lithium toxicity is ventricular dysrhythmias.

Lithium toxicity can be acute or chronic, with the clinical difference often only a matter of degree. CNS or neuromuscular symptoms of toxicity (confusion, ataxia, dysarthria, seizures, tremors, fasciculations) predominate. Gastrointestinal (nausea, vomiting) and cardiovascular (bradycardia, PVCs, hypotension) findings are also common. The most common cardiac dysfunction is sinus node dysfunction. Lithium causes renal tubular dysfunction and sodium loss even in therapeutic doses, causing a compensatory increase in lithium reabsorption. Natriuretic diuretics (furosemide) will thus tend to increase serum levels. In general, clinical findings are more important in judging lithium toxicity, since “toxic” levels of >2 mEq/L are occasionally therapeutic, and “therapeutic” levels (<2 mEq/L) toxic. Volume replacement with normal saline to create euvolemia is essential. Hemodialysis is indicated in the acute ingestion when the serum lithium level is >4.0 mEq/L and in the chronic ingestion when the lithium level is >2.5 mEq/L. Hemodialysis is also indicated in the patient with renal failure, or in the patient with neurologic dysfunction including an altered mental status. Hypothyroidism and nephrogenic diabetes insipidus are other complications of lithium therapy.