Acute organic psychosis caused by thyrotoxicosis and vitamin B12 deficiency: case report.

A 64-year-old woman developed an acute organic psychosis secondary to thyrotoxicosis and B12 deficiency, without the overt clinical features of pernicious anemia. The psychosis resolved with B12 and thyroid hormone replacement. The patient relapsed after an erroneous iatrogenic tripling of the levothyroxine dosage, but her condition normalized after dosage correction.