The incidence rate of pituitary adenomas in western Sweden for the period 2001–2011

ObjectiveThe number of studies on the incidence of pituitary adenomas (PAs) is limited. The aim of this study was to evaluate the standardised incidence rate (SIR) of PAs in western Sweden.Design, subjects and methodsData from adult patients diagnosed with PAs in 2001–2011, living in the Västra Götaland County, were collected from the Swedish Pituitary Registry (SPR). In addition, medical records on all patients diagnosed with PAs at the six hospitals in the region were reviewed. In total, 592 patients were included in the study.Age-SIR, given as rate/100 000 inhabitants (95% CI), was calculated using the WHO 2000 standard population as a reference.ResultsThe total SIR for PAs was 3.9/100 000 (3.6–4.3); 3.3/100 000 (2.9–3.7) for men and 4.7/100 000 (4.1–5.3) for women. In men, SIR increased with age, while in women SIR peaked at 25–34 years, mainly due to prolactinomas. Non-functioning PA (NFPA) was the most common PA (54%, 1.8/100 000 (1.6–2.0)) followed by prolactinomas (32%, 1.6/100 000 (1.3–1.9)), acromegaly (9%, 0.35/100 000 (0.25–0.45)), Cushing's disease (4%, 0.18/100 000 (0.11–0.25)) and TSH-producing PA (0.7%, 0.03/100 000 (0.00–0.05)). The proportion of macroadenomas for NFPA was 82%, prolactinomas 37%, GH-producing PA 77%, ACTH-producing PA 28% and TSH-producing PA 100%. The lifetime risk for PAs was 0.27% (0.24–0.31) in men and 0.29% (0.26–0.33) in women.ConclusionThis study provides a reliable estimate on the overall incidence of PAs and confirms an increased incidence of PAs compared with studies conducted in the pre-magnetic resonance imaging era. The lower proportion of prolactinomas compared with previous studies is probably explained by the different criteria used.