Asymptomatic and mild primary hyperparathyroidism

Primary hyperparathyroidism is common, with epidemiological studies suggesting it may effect up to 1% of the population, and up to 3% of post-menopausal females. Many cases are diagnosed incidentally on routine blood sampling, with the majority of patients being seemingly asymptomatic at diagnosis, and often having mild hypercalcaemia of <2.85. mmol/L. Individuals with this so-called mild or asymptomatic primary hyperparathyroidism may however have undiagnosed complications, along with subtle neuropsychological symptoms, and possibly increased cardiovascular risk. Revised international guidelines suggest a more proactive approach to screening for vertebral fractures and renal stones, although the thresholds for recommending definitive surgical management with parathyroidectomy remain similar. The natural history of mild primary hyperparathyroidism will be reviewed, with particular reference to the Parathyroid Epidemiology and Audit Research Study (PEARS), which has used population level data from Tayside, Scotland (UK), along with recent data describing an association with cardiovascular disease. Results of intervention studies, including randomised controlled trials, will also be discussed.