A 54-year-old woman who was being treated with 10 million units (mu) o
f natural interferon (IFN)-alpha per day for chronic active hepatitis
C al. a local clinic, developed coma on the fourth day of treatment. O
n admission to Yamagata University Hospital, she was still in a state
of semicoma with severe hyponatraemia (122 mEq/L) and hypochloraemia (
89 mEq/L). After the administration of electrolytes, her condition imp
roved remarkably. Endocrinological loading tests showed a hypofunction
of the anterior pituitary gland. In consideration of these results, a
nd her past experiences of haemorrhage during childbirth and subsequen
t amenorrhoea, we diagnosed her illness as a coma as a result of Sheeh
an's syndrome which had become overt during IFN therapy. She recovered
completely after treatment with hydrocortisone and 1-thyroxine.