Guía clínica del diagnóstico y tratamiento de la disfunción tiroidea subclínica

Request of thyroid function tests from Primary Care in Spain

BACKGROUND AND OBJECTIVES

Laboratory tests are crucial for diagnosis and monitoring of thyroid disorders. It is therefore necessary to study the pattern and variability in requests of thyroid function tests. The study objectives were to compare the inter-regional variability in the request of laboratory thyroid tests by general practitioners (GPs) in Spain, and to investigate the potential economic savings if the goals set for some suitability indicators were reached.

METHODS

Test requests per 1,000 inhabitants and test ratios (free thyroxine (FT4)/thyrotropin (TSH), free triiodothyronine (FT3)/TSH, thyroglobulin antibody (TgAb)/peroxidase antibody (TPOAb)) were compared between the different areas, according to their setting, location, and management. The resulting savings if each department achieved the goals for indicator (0.25 for FT4/TSH, 0.1 for FT3/TSH) were estimated.

RESULTS

Seventy-six laboratories covering a population of 17,679,195 inhabitants participated in the study. TSH was requested significantly less in urban-rural areas, and the requests for FT3/1,000 inhabitants, FT3/TSH, and TgAb/TPOAb were higher in departments with private management. The savings generated if specifications for the ratios of related tests were met would be 937,260.5 €.

CONCLUSIONS

The high variability reported in requests for thyroid function and autoimmunity tests in Spain suggests the need for implementing strategies to improve use of such tests.

[Short-term results of treatment with 131I in patients with multinodular goiter: effect of the associated degree of hyperthyroidism and other variables]

OBJECTIVE

To assess the effectiveness of radioactive iodine (RAI) therapy and the incidence of hypothyroidism post RAI in patients with subclinical hyperthyroidism or clinical hyperthyroidism with Multinodular Goiter (MNG).

METHODS

A retrospective study of 69 consecutive patients treated with (131)I for MNG during the year 2008 observed for six months. All patients received a single fixed dose of 16 mCi (592 MBq) weighted by the gland size. They were categorized into two groups: subclinical hyperthyroidism or clinical hyperthyroidism. We compared the success rate and the incidence of hypothyroidism.

RESULTS

The thyroid dysfunction was corrected in 82.09% of the patients. Success rate was 100% in the clinical hyperthyroidism group and 78.13% in the subclinical hyperthyroidism group (P=0.105). The overall incidence of hypothyroidism was 16.42%; 25.00% of patients with clinical hyperthyroidism and 14.55% with subclinical hyperthyroidism developed this secondary effect (P=0.400). No statistically significant differences were found in the success rate in the incidence of hypothyroidism when the results were analyzed according to the thyrotropin decrease in patients with subclinical hyperthyroidism. Seven patients had positive anti-thyroid peroxidase antibodies (anti-TPO) before therapy. The incidence of hypothyroidism was significantly higher in them (57.14% vs 11.67%; P=0.011). Cardiac arrhythmias were four times more frequent in patients with clinical hyperthyroidism. Previous treatment with thiamazol positively affected the outcome.

CONCLUSIONS

A single fixed weighted dose of (131)I is highly effective and safe for the control of clinical and subclinical hyperthyroidism due to MNG. Patients with anti-TPO antibodies may have a high risk of developing post-iodine hypothyroidism.

Undiagnosed thyroid dysfunction, thyroid antibodies, and iodine excretion in a Mediterranean population

The prevalence of thyroid dysfunction varies in different populations. The aim of this cross-sectional study was to analyze the prevalence of undiagnosed thyroid dysfunction and thyroid antibodies and their relationship with urine iodine excretion in a representative sample of 1,124 (55.5% women; mean age: 44.8 ± 15.2 years) non-hospitalized Mediterranean adults, in Catalonia (Spain). Free thyroxine, thyroid-stimulating hormone, thyroperoxidase and thyroglobulin antibodies, and urine iodine were measured. Undiagnosed thyroid dysfunction was 5.3% (hypothyroidism 3.8%; 56.66% of these subjects were women). The total (diagnosed + undiagnosed) thyroid dysfunction was 8.9% (71.15% women). Thyroperoxidase antibodies were positive in 2.4% of men and 9.4% of women and thyroglobulin antibodies, in 1.3% of men and 3.8% of women. No differences were observed in urine iodine between groups with thyroid dysfunction and euthyroidism, or between subjects with positive or negative antibodies. In subjects over 60, undiagnosed thyroid dysfunction was 9.8% (hypothyroidism 6.9%, hyperthyroidism 3.3%; 36.36% women) and total thyroid dysfunction 13.61% (53.12% women). Women and men over 60 had similar thyroid dysfunction prevalence. Thus, aggressive case-finding should be recommended in both, over 60.