Endocrine Abstracts

The high prevalence of thyroid disease necessitates efficient and effective monitoring. We expanded a hospital-based register to a managed clinical network for almost 10,000 patients with thyroid disease. Evaluation of our network compared to register data from 1991 demonstrates changing trends in treatment of hyperthyroidism. Use of radio-iodine significantly increased (58 percent v 44 percent; p less than 0.001) with a reduction in thyroid surgery (34 percent v 47 percent; p less than 0.001); use of medical treatment remains static (8 percent v 9 percent). Between radio-iodine and thyroidectomy, rates of hypothyroidism (91 v 92 percent) and mean thyroxine dosages (117 plus/minus 37 v 121 plus/minus 43 micrograms) were similar. The network has facilitated greater precision in thyroxine replacement to achieve a TSH concentration within the normal range. The high rate of TSH suppression (TSH less than 0.03 milliunits per litre) in patients on thyroxine (58.5 percent in 1991) had reduced to 4.9 percent by 1993 (p less than 0.001) and thereafter was consistently below 10 percent. Rates of elevated TSH (greater than 0.4 milliunits per litre) have increased only slightly (3.5 percent to 5.6 percent; p less than 0.01). A TSH concentration of less than 0.1 milliunits per litre has been associated with increased risk of cardiovascular and cerebrovascular disorders, vertebral fractures and dementia, so the network has enabled a decision to be made, based on cost and patient numbers, on thyroxine dosage adjustment in cases of low TSH. Previously adjustment only occurred with TSH less than 0.03 milliunits per litre (463 patients; 6.4 percent of patients on thyroxine); now dosage adjustment occurs to elevate TSH greater than 0.1 milliunits per litre (1100 patients; 15.1 percent of patients on thyroxine). We believe the clinical thyroid network has enabled monitoring of treatment changes and improved precision in thyroxine replacement.