110
469 μg, and 532.8 μg, respectively. Serum cortisol after overnight dexametha-
sone suppression test (ONDST) was 464 nmol/L, low-dose dexamethasone sup-
pression test (LDDST) 408 nmol/L, and after high-dose dexamethasone
suppression test (HDDST) was 157 nmol/L. Serum prolactin was 8.63 ng/ml (N
4.7–23.3), T 4 7.02 μg/dl (N 4.8–12.7), TSH 0.894 μIU/ml (N 0.27–4.2), testos-
terone 0.32 nmol/L (N 0.2–2.9), LH 0.24 mIU/ml (N 2.4–12.6), and FSH
0.32 mIU/ml (N 3.5–12.5). Ultrasound pelvis showed normal ovaries and uterus.
Dynamic contrast-enhanced MRI sella revealed differentially enhancing
4.8 × 4.0 mm lesion which was hypointense on T1W and hyperintense on T2W
images in the left half of the pituitary gland. She underwent bilateral inferior
petrosal sinus sampling (IPSS) with 100 μg (IV bolus) human CRH. IPSS local-
ized the source of ACTH excess to the pituitary and lateralized to right side of the
pituitary gland. Serum ACTH and cortisol profi le during IPSS are summarized in
the table given below. She underwent transsphenoidal surgery; intraoperatively
tumor was localized to the left side of the pituitary, and excision of the tumor was
accomplished. Patient developed left lateral rectus palsy postoperatively, which
recovered within 2 weeks. She was documented to have hypocortisolemia
(83.5 nmol/L) on day 1 postoperatively and was started on hydrocortisone sup-
plementation. Histopathology of the tumor tissue showed pituitary adenoma,
while immunostaining for ACTH was negative. At 6 weeks, she had weight loss
of 5 Kg, resolution of plethora, disappearance of acne, and violaceous striae
started fading. An 0800h serum cortisol after the omission of hydrocortisone
for 24h was 4.6 nmol/L, and serum T 4 was 10.5 μg/dl. She is continued with
hydrocortisone supplementation and advised to follow up every three monthly
(Fig. 4.1 ).