Increasing incidence and prevalence of biochemically confirmed primary hyperparathyroidism in Stockholm, 2006-2020

Primary hyperparathyroidism (PHPT) prevalence appears to be rising, but substantial underdiagnosis persists. Accurate epidemiological data are needed, requiring population-based studies using strict biochemical criteria.

To determine incidence and prevalence of biochemically confirmed PHPT in Stockholm and characterize clinical recognition and surgical management.

This is a population-based healthcare cohort study using prespecified biochemical diagnostic algorithms in the Stockholm Region, Sweden, 2006-2020, using the Stockholm CREAtinine Measurements database which covers two-thirds of the adult population, including ≥90% of individuals ≥65 years. Adults aged ≥20 years with paired calcium and parathyroid hormone (PTH) measurements meeting biochemical criteria for PHPT were included. Individuals with estimated glomerular filtration rate ≤30 mL/min/1.73 m2, secondary hyperparathyroidism, or prior parathyroid surgery were excluded. Main outcome measures were the annual incidence rate and point prevalence of biochemically confirmed PHPT.

Among 176 780 individuals contributing 578 227 PTH measurements, 10 190 patients fulfilling biochemical PHPT criteria were identified. Age- and sex-adjusted incidence rate increased from 2.81 (95% CI, 2.55-3.09) to 4.28 (95% CI, 3.98-4.59) per 10 000 person-years between 2009 and 2020, with the steepest increase among women aged ≥70 years. Prevalence increased from 0.35 to 4.76 per 1000 individuals. Median ionized calcium was 1.39 mmol/L. Clinical diagnosis of PHPT was documented in 5346 (52%) patients, of which 2800 (52%) underwent parathyroidectomy, with surgery rates stabilizing after 2013 at 4% to 5% annually.

Using a large healthcare database, we observed substantially increasing PHPT incidence and prevalence, predominantly in older individuals. Only 52% received clinical diagnosis, underscoring the need for studies evaluating the long-term clinical burden of undiagnosed PHPT.