Endocrine Abstracts

Introduction: TSH-secreting pituitary adenomas (TSHoma) are rare. Epidemiological data are scant and there are no reports on national incidence. The aim of this study was to estimate the national incidence and prevalence of TSHomas in Sweden.

Methods: This is an observational study from all tertial referral centers where the Swedish Pituitary Registry and WHO ICD coding were used to identify patients diagnosed with TSHomas in Sweden 1990–2010. Medical records were studied for identified patients until latest follow-up (median 5.0 years (range <1–20)). Incidence, prevalence, demography, tumor characteristics, treatment outcome and thyroid hormone level at diagnosis were studied.

Results: The age-standardized national incidence of the 28 TSHoma patients was estimated to 0.15/million inhabitants/year for the period, with an increasing incidence over time (0.05/million/year in 1990–1994 to 0.26/million/year in 2005–2009). The national prevalence of patients followed for TSHomas in 2010 was 2.8/million inhabitants. Most patients (n=22) underwent surgery, three had radiotherapy and six had somatostatin analogues. In total, 18 patients were considered cured at latest follow-up; 25% remained uncontrolled. Subjects treated for putative thyroid illness prior to diagnosis (n=8) had TSH levels more than two times compared with those with intact thyroid at diagnosis of TSHoma, P=0.013. Women had longer time to diagnosis than men, median 4 vs <1 years, P=0.026 and had more often surgery, 94.1 vs 54.5%, P=0.022.

Conclusion: This is the first estimation of a national incidence of TSHomas. Additional epidemiological studies are needed to compare this result with other geographical areas. The study implies an increased incidence of TSHomas, in parity with reports on other pituitary adenomas.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.