Hyperthyroidism exaggerating parkinsonian tremor: a clinical lesson.

We present the clinical description of a 70-year-old man with parkinsonian tremor, which was severely exaggerated by hyperthyroidism. Clinical diagnosis of hyperthyroidism was overshadowed by the parkinsonian symptoms. Anti-thyroid treatment had a beneficial effect on the exaggerated parkinsonian tremor. This case report highlights that thyroid dysfunction should be considered in the differential diagnosis of aggravated tremor in Parkinson's disease which seems refractory to increased dosages of anti-parkinsonian drugs.