Difference in symptom profile between generalized anxiety disorder and anxiety secondary to hyperthyroidism

The differential diagnosis between subclinical hyperthyroidism and Generalized Anxiety Disorder (GAD) is often a difficult problem to solve without laboratory examination. The aim of this pilot study was to assess whether there are differences in the symptom profile between these two disorders.

Fifty patients took part in the study: Twenty-five were hyperthyroid patients, and twenty-five were GAD patients. The diagnosis was based on the TSH values and the DSM-IV criteria, respectively. The Hamilton Anxiety Scale (HAS) and the list of fifty-one symptoms produced by the detailed expansion of HAS items were used to quantify the anxiety symptomatology. The differences in the frequencies between the two diagnostic groups were calculated at each categorical response for every item of both scales. Forward Stepwise Discriminant Function Analysis was performed twice using HAS items and the fifty-one-list items.

The symptoms of anxiety in subclinical hyperthyroidism were not identical to those of GAD. Four Hyperthyroid/Anxiety Indices (HAI I-IV) were developed. These indices reach optimum classification of patients (3 of them reach 100% sensitivity and specificity).

The results of the current study suggest that it is possible to differentiate between GAD and subclinical cases of hyperthyroidism by the careful study of clinical symptomatology. This may be of particular help in isolated areas without laboratory support, but replication of the indices in other samples is indicated.