Hyperparathyroidism and medullary sponge kidney. A chance relationship?

PATIENTS with medullary sponge kidney frequently have nephrocalcinosis, nephrolithiasis, and hypercalciuria. The cause of the augmented calcium excretion is unknown. Because of these frequent associations, there has been no impelling reason to seek other causes to explain these manifestations. Recent case reports 1,2 emphasize the presumably chance occurrence of hyperparathyroidism with medullary sponge kidney. The true incidence of this association is unknown. Morris 3 has recently suggested that hyperparathyroidism is capable of inducing a renal lesion urographically indistinguishable from medullary sponge kidney. This implies that the morbidity from medullary sponge kidney might be diminished if hyperparathyroidism could be detected and surgically treated. This report describes the fourth reported case with coexisting hyperparathyroidism and medullary sponge kidney and complements previous observations of this unusual association. Report of a Case A 38-year-old woman had passed stones or gravel at monthly intervals for about 18 years. She was found to have unexplained hypercalciuria