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SIADH closely associated with non-functioning pituitary adenoma.
Masaru Kanda1, Yoshio Omori, Soji Shinoda
1Department of Surgical Neurology, Jichi Medical School, Omiya Medical Center, Saitama, Japan.
Endocrine Journal
|September 8, 2004
Summary
A pituitary tumor caused severe hyponatremia (low sodium) in a patient by triggering excessive arginine vasopressin (AVP) release, mimicking the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Surgical removal of the tumor resolved the condition.
Area of Science:
- Endocrinology
- Neurosurgery
- Oncology
Background:
- Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) is a common cause of hyponatremia.
- Pituitary tumors can present with diverse endocrine dysfunctions.
Observation:
- A 68-year-old male presented with disorientation and severe hyponatremia (serum sodium 112 mmol/l).
- Physical examination revealed disturbed consciousness (Japan Coma Scale I-2) without dehydration or edema.
- Laboratory results showed marked hypoosmolality with concentrated urine and suppressed plasma arginine vasopressin (AVP) levels.
Findings:
- Brain MRI revealed a pituitary tumor compressing the pituitary stalk.
- Anterior pituitary function tests were normal.
- Post-adenomectomy, serum sodium normalized spontaneously, indicating the tumor was the cause of SIADH.
Implications:
- Local pituitary tumors can induce SIADH through mechanisms potentially involving ectopic AVP production or altered AVP regulation.
- This case highlights the importance of considering pituitary pathology in patients with unexplained SIADH.
- Surgical resection of pituitary adenomas can effectively treat hormone-related disorders like SIADH.