Medullary sponge kidney and hyperparathyroidism--a puzzling association

Area of Science:

• Nephrology
• Endocrinology
• Urology

Background:

• Medullary sponge kidney (MSK) is a congenital renal malformation.
• Hypercalcemia and hyperparathyroidism are potential complications.
• The relationship between MSK and calcium metabolism disorders requires further investigation.

Purpose of the Study:

• To investigate the prevalence and nature of calcium metabolism disorders in patients with medullary sponge kidney.
• To explore the association between MSK and hyperparathyroidism.
• To determine the impact of parathyroid surgery on calcium homeostasis in these patients.

Main Methods:

• Retrospective study of 28 adult patients with radiologically confirmed MSK.
• Assessment of serum calcium, parathyroid hormone (PTH), and urinary calcium levels.
• Evaluation of patients undergoing parathyroid surgery for hyperparathyroidism.

Main Results:

• 36% of patients exhibited hypercalcemia and elevated PTH; 7 underwent parathyroid surgery with varied outcomes.
• 4 patients had persistent hypercalciuria post-surgery, with one experiencing adenoma recurrence.
• 36% had hypercalciuria (renal leak or intestinal hyperabsorption), and 28% had normal calcium metabolism.

Conclusions:

• The association between MSK and hyperparathyroidism is significant, suggesting MSK may be a complication or consequence of hyperparathyroidism-induced hypercalciuria.
• Parathyroid surgery can normalize calcium metabolism in some MSK patients, but recurrence and persistent hypercalciuria can occur.
• The high prevalence of normal calcium metabolism in some MSK patients indicates the complexity of MSK pathogenesis, leaving its full understanding incomplete.