Endocrine Abstracts

Background and aims: Primary hyperparathyroidism (PHPT) is a common endocrine disorder with different epidemiological patterns among countries. The incidence of PHPT is unknown in Spain. The aim of our study is to assess the prevalence and incidence of diagnosed PHPT in adults between 1970 and 2014 in Santander, a population of 290.000 inhabitants, located in the north of Spain.

Subjects and methods: All patients diagnosed with primary hyperparathyroidism from 1970 to 2014 were included. PHPT was diagnosed when persistent hypercalcemia occurred with the presence of elevated or inappropriately normal parathyroid hormone levels. Prevalence and incidence density adjusted for age and sex were calculated for each 5-year period.

Results: We identified 709 patients (82.3% females) diagnosed with PHPT by the end of 2014. Females were older than males at baseline (median age 67.6 years (57.8–75.9) and 63.7 years (52.1–74.2) respectively) (P<0.05). Prevalence of PHPT was higher in females, and the female preponderance increased with age. In the mid-1990s the incidence rate in women was 3.72/100.000 person-years and doubled in the period 1995-1999, with an incidence rate of 8.38/100.000 person-years. Incidence increased in the following years, and in the period from 2005 to 2009, it doubled again from 12.08/100.000 person-years in 2000 to 2004 to a maximum level of 24.52/100.000 person-years in the period from 2005 to 2009. In the last period of study, from 2010 to 2014, the incidence in women decreased up to 21.44/100.000 person-years. The increased incidence is progressive and less flashy in males than females. The incidence in the period from 1995 to 1999 was 2.75/100.000 person-years and doubled in the period from 2010 to 2014, becoming 5.20/100.000 person-years. The prevalence of diagnosed PHPT in Santander increased from 0.01 per 1000 population in the period from 1980 to 1984 to 0.38 per 1000 population in the period from 2010 to 2014.

Conclusions: The incidence of PHPT in Santander continues its remarkable rise. The incidence of diagnosis is greater in females than in males and increases with age. The overall increase in incidence may be the result of more frequent plasma calcium measurements, periods of increasing medical interest or environment factors. However, the most likely explanation is the bias of the selective detection of PHPT in patients who are being evaluated for osteoporosis.