Masked "myxedema madness".

Hypothyroidism can present a wide range of psychiatric manifestations, including personality disturbance, neurotic traits and psychotic features. Psychiatric treatment techniques without recognition and correction of the endocrine root of the mental disturbance will result in a failure of treatment. However, severe hypothyroidism can exist with a poverty of classical signs and symptoms such that both internist and psychiatrist may easily overlook endocrine dysfunction as a possible etiology of the mental disorder. A case of long-standing paranoid illness whose etiology was severe myxedema with such a poverty of signs and symptoms is presented. Failure to recognize the endocrinopathy may not only produce recovery difficulties but also psychiatric and endocrine repercussions if psychotropic medications are given in such masked cases. These problems are considered with particular reference to lithium, and screening criteria to avoid this problem are discussed.