Endocrine Abstracts

Primary hyperparathyroidism (PHPT) is a common endocrine disorder that is characterized by hypercalcaemia and elevated or inappropriately normal levels of parathyroid hormone (PTH), which is excessively secreted from one or more parathyroid glands. Classical disease is nowadays only seldom seen due to widespread biochemical screening. Most patients are asymptomatic and have more subtle, but clinically important skeletal and renal involvement. A normocalcaemic variant of the disease with high PTH levels and persistently normal serum calcium values is sometimes diagnosed during the evaluation of osteoporosis. Parathyroidectomy is the only curative option and the procedure of choice for all patients with symptomatic PHPT. Guidelines for surgery in asymptomatic disease include age < 50 years, increased serum calcium > 0.25 mmol/l (1 mg/dl) above upper limit of normal, reduced bone mineral density (BMD) by DXA to a T-score of < - 2.5 S.D. at any site and/or a vertebral fracture by imaging, creatinine clearance < 60 ml/min, kidney stone or nephrocalcinosis by imaging, hypercalciuria > 400 mg/day accompanied by biochemical stone risk profile placing patient at risk of kidney stones. Patients who do not meet surgical criteria or those who decline surgery should be monitored for signs of disease progression. If surgery is not an option, pharmacological approaches are available and effective. Medical management starts with correction of dietary calcium and vitamin D insufficiency. Cinacalcet is a calcimimetic agent that effectively reduces calcium levels, but does not appear to have any effect on BMD. On the other hand, alendronate improves BMD without any changes in the serum calcium. Less data is available for other bisphosphonates and denosumab. Recently, thiazides have re-emerged as a potentially effective and safe option for controlling hypercalciuria in selected patients with PHPT, but careful monitoring for hypercalcemia is required.