Actual practice vs guidelines in laboratory monitoring of older patients with primary hypothyroidism in primary care

Background and aims: Clinical guidelines are produced in order to achieve an acceptable standard of care, especially for patients with common diseases in primary care. The treatment of primary hypothyroidism serves as an example of the content of clinical guidelines and actual practice. The aim of this study was to compare the follow-up of primary hypothyroidism by thyroid function tests, serum TSH and serum-free T4, in older patients managed in primary care, with recommendations in treatment guidelines and textbooks. Methods: Participation rate 82% (n=1260), mean age 74 years, (range 64–100 yrs). Patients with primary hypothyroidism were identified by means of cross-sectional survey (Lieto Study 1998–1999) and 4-year retrospective collection of laboratory database medical records (1994–1998), performed in autumn 2003. Results: In most stable (=treated for more than 14 months) thyroxine users, both serum TSH (mean 1.4 measurements/year) and serum-free T4 (mean 0.8 measurements/year) values were measured over the 4-year period of thyroxine treatment. 66.4% of serum TSH and 85.3% of serum-free T4 values were within normal range. 41.7% of serum-free T4 determinations had been performed without indication (=with TSH in normal range). Conclusions: Compared with the recommended testing frequency given in various guidelines, a considerable number of extra measurements, especially serum-free T4, were performed. However, some key issues in the recommendations were difficult to interpret, and the age or other main characteristics of the patient were not taken into consideration adequately.