Subclinical Hyperthyroidism, an Under-Recognized Entity

Purpose: Determine the medical evaluation completed and the clinical progression observed in subjects with Endogenous Subclinical Hyperthyroidism (ESCH).Method: This is a single site retrospective chart review of subjects who visited the Ambulatory Care Clinics at the James A. Haley VA Hospital (JAHVA), Tampa, Florida. Subjects were selected and charts reviewed using the automatic data mining tool. Inclusion criteria encompassed subjects’ low thyroid stimulating hormone (TSH) and normal T4 and T3 levels.Results: 95 subjects met criteria for inclusion. At the end of one year, 48 (51%) had normal thyroid function tests (TFTs), 43 (45%) had persistent ESCH and 4 (4%) had overt hyperthyroidism. A radioiodine thyroid uptake/scan was completed in 32 (33%) subjects. Only 9 (10%) had thyroid stimulating Immunoglobulin (TSI) or anti-thyroid peroxidase antibody (anti-TPO) studies. A bone density study was not completed. Conclusions: Out of the 95 subjects with ESCH, at the end of one year 51% had normal TFTs, 45% had persistent ESCH and 4% had hyperthyroidism. Less than 50% of the subjects received further tests. It is recommended that subjects with ESCH be followed periodically with TFTs and further evaluation may be required to assess cause, severity, risk of complications and need for treatment.