Primary hyperparathyroidism and nephrolithiasis.

Calcifications in the kidneys may occur in the parenchyma (nephrocalcinosis), pelvis renis (nephrolithiasis) or ureters (ureterolithiasis). Several factors may protect against stone formation or promote precipitation of stones. Most stones contain calcium, and the hypercalciuria seen in primary hyperparathyroidism is a contributing factor to stone formation in the kidneys and urinary tract. In early case series, renal stone formation was frequent, whereas the proportion of patients with symptomatic renal stones has declined in recent years. However, a substantial proportion of patients presents with asymptomatic nephrocalcinosis or nephrolithiasis. Before diagnosis and treatment of primary hyperparathyroidism, renal stone events are more frequent than in the general population. However, even after surgical cure, an increased rate of renal stone events may be seen. This may to some extent be the result of stones or calcifications already present at the time of diagnosis or sequelae to prior stones such as infections or ureter strictures.