SUN-419 Monitoring Thyroid Function Tests in Patients on Lithium: Adherence to Recommended Guidelines and Comparison of Practice Patterns in a Health Care System

It is well known that Lithium causes various types of thyroid dysfunction. Thus, multiple professional guidelines, for example the American Psychiatry Association, recommend that thyroid function be assessed before starting lithium therapy, within the first 6 months of initiation, and then every 6 to 12 months. We hypothesized that these recommendations are not consistently followed by all types of providers. Methods A total of 796 patients were identified by chart review with age ≥18 years and ICD 9/10 codes for bipolar disorder or on lithium in outpatient clinics in our multicenter system from January 2013 to December 2017. Results Lithium start date was known in 472 (59.3%) of 796 patients. Of these 796 patients, 518 (65 %) were followed by psychiatry, 25 (3%) by family medicine, 60 (7.5%) by internal medicine, and 193 (24%) by other specialties including endocrinology and emergency department. Patients with unknown start date were excluded from analysis of baseline and follow-up TSH. Baseline TSH was done in 178 (37%) of patients with known start date. Of these patients, 141 (79%) were followed by psychiatry, 13 (7%) by internal medicine, and 8 (4%) by family medicine. Of the 472 patients, 76 (16%) had 6-month TSH by psychiatry (42; 60.5%), internal medicine (17; 22%), and family medicine (3; 4%). Of the 796 patients on lithium, 568 (71%) had random TSH values, 200 (25%) had abnormal thyroid function tests (TFTs), and only 69 (34%) had baseline TFTs before lithium was started. Of the 200 patients with abnormal TFTs, 90 (45%) developed thyroid disease. The odds of baseline TSH for family practice and internal medicine were not significantly different than for psychiatry, (OR = 1.3 p = 0.6, and OR = 0.7, p = 0.3, respectively). Internal medicine had 5.1 times higher odds of TSH at 6 months compared with psychiatry (p <0.001). The odds of 6-month TSH for family practice were not significantly different than for psychiatry. Conclusion Our findings revealed that TSH was not checked in most patients before starting lithium therapy and TSH values were not followed at recommended intervals. This raises the concern that a large number of patients may have undiagnosed thyroid dysfunction due to inappropriate follow up. Future plans include a quality improvement project to focus on improving practice patterns, such as EMR reminders to prompt providers when TFTs are due and educating providers about the guidelines.