1,25-dihydroxyvitamin D mediated hypercalcemia in seminoma

Area of Science:

• Endocrinology
• Oncology
• Nephrology

Background:

• Hypercalcemia is infrequently associated with seminomas, with limited understanding of its underlying pathophysiology.
• Existing literature lacks comprehensive data on the mechanisms driving hypercalcemia in seminoma patients.

Purpose of the Study:

• To present a case of metastatic seminoma presenting with severe hypercalcemia.
• To investigate the potential mechanisms of hypercalcemia in this seminoma case.
• To review and analyze previously reported cases of hypercalcemia associated with seminoma.

Main Methods:

• Clinical case presentation of a 59-year-old male with symptoms of hypercalcemia and unintentional weight loss.
• Laboratory analysis including serum calcium, 1,25-dihydroxyvitamin D, parathyroid hormone (PTH), PTH-related peptide (PTHrP), 25-hydroxy vitamin D, and phosphorus.
• Literature review of reported seminoma cases with associated hypercalcemia.

Main Results:

• The patient presented with severe hypercalcemia (16.2 mg/dL) and was diagnosed with metastatic seminoma.
• Elevated 1,25-dihydroxyvitamin D levels (>200 pg/mL) and suppressed PTH (11 pg/mL) indicated 1,25-dihydroxyvitamin D-mediated hypercalcemia.
• Review of 11 cases revealed that elevated 1,25-dihydroxyvitamin D is a consistent finding in seminoma-associated hypercalcemia.

Conclusions:

• Seminoma-associated hypercalcemia is predominantly mediated by elevated 1,25-dihydroxyvitamin D.
• While 1,25-dihydroxyvitamin D appears to be the primary driver, other mechanisms like PTHrP elevation may coexist in some cases.
• Further research is warranted to fully elucidate the diverse pathophysiological mechanisms of hypercalcemia in seminoma.