[Attempted suicide with L-thyroxine in an adolescent girl]

Attempted suicide with l-thyroxine (LT4) is very rare, only being published in some case reports concerning young women. Experiences in the management of LT4 intoxication have already been made because overdosage in infants occurs more often. Guidelines and recommendations depend on the quantity of LT4 that has been ingested.

A 17-year-old girl presented to the pediatric emergency department after intentional ingestion of 20 mg of LT4 20 hours prior to admission. Anamnestically she had increased the thyroxine dose rate up to 800 microg per day during the previous 4 months in order to obtain loss of weight. In spite of massive overdosage and extremely high serum thyroxine levels (fT4 794 pg/ml, TSH suppressed) the girls showed low symptoms and a mild clinical course. Because of tachycardia, hyperhidrosis and muscle tremor propranolol was applied. During the following 22 days fT4 levels returned to normal range and the adolescent was remitted to the outpatient clinic of the department of psychiatry. Whereas patients with graves disease and thyreotoxicosis present with severe symptoms our patient showed a mild clinical course in spite of having extremely high fT4 levels.

The reasons are ambiguous. A possible answer could be an adaptation in higher fT4 levels in cause of the reported chronic LT4 overdosage.