Nephrolithiasis and Renal Calcifications in Primary Hyperparathyroidism

Abstract

Renal complications in terms of hypercalciuria, nephrolithiasis, and nephrocalcinosis are well-known risks in primary hyperparathyroidism (PHPT) and may lead to impaired renal function. We reviewed published evidence on the occurrence, pathophysiology, and consequences of renal complications in PHPT and highlighted areas of uncertainty that should be investigated further. In asymptomatic PHPT, renal stones are present in approximately 7% of the patients, which is a significantly higher prevalence than among patients without PHPT (1.6%). Also, before diagnosis of PHPT, risk of hospital admissions due to renal stones is increased compared with the background population, and the risk remains increased for at least 10 yr after surgical cure from PHPT. However, shortly after parathyroidectomy, risk of recurrent stone episodes is reduced to the recurrence rate among patients with idiopathic renal stone disease. In general, patients with PHPT who develop nephrolithiasis are of younger age and more often are males, compared with those who do not form renal calcifications. Although 24-h urinary calcium is decreased after parathyroidectomy, studies have shown a higher renal calcium excretion and lower serum phosphate levels in former PHPT patients compared with healthy controls, suggesting that these patients have some additional mineral disorder. All patients with a diagnosis of PHPT should initially be evaluated for renal calcifications by unenhanced helical computed tomography. If calcifications are present, parathyroidectomy is recommended. If symptoms develop after parathyroidectomy, patients should be evaluated and treated similar to other patients with renal stones.