Introduction: Recent studies show an association between hyponatremia and osteoporosis. We have previously reported a case of severe male osteoporosis due to chronic syndrome of inappropriate secretion of antidiuretic hormone (SIADH). Here, we provide a follow-up on this case after cure of the condition that further supports the causal relationship. The Case: A 38-year-old man had been diagnosed with severe osteoporosis most likely due to chronic SIADH. The SIADH was believed to be idiopathic. A magnetic resonance imaging scan, however, revealed a tumor in the sinus, and biopsies showed an esthesioneuroblastoma, immunohistochemically positive for antidiuretic hormone (ADH). After the tumor was removed, ADH and sodium levels normalized. A dual-energy x-ray absorptiometry scan performed 7 months after the patient's last surgery showed a significant spontaneous improvement in bone mineral density in the lumbar vertebrae. Conclusion: This case provides evidence for a causal relationship between SIADH and chronic hyponatremia and impaired bone metabolism that can lead to severe secondary osteoporosis. The effect on bone metabolism is at least partially reversible.
Journal of Clinical Endocrinology and Metabolism, 2014, Vol 99, Issue 10, p. 3527-3530