Persistent SIADH-like Hyponatremia Requiring Tolvaptan Despite Glucocorticoid Replacement in Rathke's Cleft Cyst-Associated Hypophysitis: A Therapeutic Dilemma.

Authors

Yuya Shimizu, Reo Ishii, Kazumasa Tanaka, Koki Kinoshita, Jun Toyama, Noriaki Fukuhara, Masahiro Nezu

Published in

Internal medicine (Tokyo, Japan). Oct 08, 2026. Epub Oct 08, 2026.

Abstract

A 52-year-old man presented with severe hyponatremia and Rathke's cleft cyst (RCC)-associated hypophysitis with enlargement of the pituitary stalk. Hyponatremia persisted despite treatment with high-dose hydrocortisone, hypertonic saline, and loop diuretics, ultimately requiring low-dose tolvaptan. Hyponatremia associated with RCC is usually attributed to secondary adrenal insufficiency (SAI), in which glucocorticoid replacement generally restores free water excretion but may unmask arginine vasopressin deficiency (AVP-D). In the present case, however, persistent AVP-mediated water retention beyond SAI appeared to predominate, suggesting AVP dysregulation associated with inflammatory pituitary involvement. This case highlights the therapeutic dilemma of balancing masked AVP-D against persistent AVP excess in hyponatremia associated with RCC.

PMID:
42844191
Bibliographic data and abstract were imported from PubMed on 08 Oct 2026.

Read full publication at:
Please sign in to see all details.

Stats

1-terrible, 9-excellent. How would you rate this publication? Sign in in to submit your rating.

Post a comment

You need to be signed in to post comments. You can sign in here.

Comments

There are no comments yet.