Adrenal insufficiency may be clinically occult yet cause life-threaten
ing complications following even minor surgery. We report the case of
a patient who became acutely hyponatremic after undergoing a marrow ha
rvesting procedure using spinal anesthesia. The initial presentation m
imicked the syndrome of inappropriate ADH (SIADH) secretion; however,
further investigation revealed Addison's disease as the underlying cau
se.