Corticotropin-Dependent Cushing Syndrome: When Inferior Petrosal Sinus Sampling Is Not Needed





Most patients with corticotropin (ACTH)-dependent Cushing syndrome (CS) will have an ACTH-secreting pituitary tumor. When a clear-cut pituitary tumor is found on magnetic resonance imaging (MRI) in a woman with slowly progressive and mild-to-moderate ACTH-dependent CS, proceeding directly to transsphenoidal pituitary surgery (TSS) is a reasonable next step. Herein we present such a case in which inferior petrosal sinus sampling (IPSS) was not needed.


Case Report


The patient was a 26-year-old woman who was referred for a second opinion on whether she might have CS. She developed very subtle signs and symptoms of glucocorticoid excess over the past 2 1/2 years. With plans for fertility, she stopped her oral contraceptive pill 3 years ago and has not had a menstrual period since. She sought consultation with a reproductive endocrinologist, and the serum prolactin concentration was normal, but the serum dehydroepiandrosterone sulfate (DHEA-S) concentration was elevated ( Table 56.1 ). Her symptoms included insomnia (routinely woke between 11:30 pm and 1:30 am and she felt “wired”), new-onset acne, mild hirsutism, and a 10-pound weight gain with distri­bution above her clavicles, in her face, and on her abdomen. She was diagnosed with new-onset hypertension 1 year ago. She had been working hard to prevent further weight gain with a high-intensity exercise program 5 days a week for 45 minutes. Her only medication was α-methyldopa, 500 mg daily. On physical examination her body mass index was 21.8 kg/m 2 , blood pressure was 138/97 mmHg, and heart rate 96 beats per minute. She did not appear overtly cushingoid. Her skin was normal and there were no purple-red striae. Her abdomen was flat. Compared to her old photographs, she did have supraclavicular fullness ( Fig. 56.1 ). She had good muscle tone and no proximal muscle weakness.



TABLE 56.1

Laboratory Tests



































































































Biochemical Test Result Repeat Test Result Repeat Test Result Reference Range
Sodium, mEq/L 142 135–145

Potassium, mEq/L

4.0

3.6–5.2

Fasting plasma glucose, mg/dL

85

70–100

Glycosylated hemoglobin, %

5.2
4–6

Creatinine, mg/dL

0.7

0.6–1.1

eGFR, mL/min per BSA

>60

>60

8 am serum cortisol, mcg/dL

23

15

22.9

7–25

4 pm serum cortisol, mcg/dL

14

2–14

24-Hour UFC, mcg

111

296

103

3.5–45

24-Hour urine volume, L

3.7

2.4

3.1

Goal <4 L

Late night salivary cortisol, ng/dL

190

210

≤100

ACTH, pg/mL

80

50

88

10–60

DHEA-S, mcg/dL

687

502

561

44–332

Prolactin, ng/mL

10

3–27

8-mg overnight DST, mcg/dL

2.1

Undetectable

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Aug 8, 2022 | Posted by in ENDOCRINOLOGY | Comments Off on Corticotropin-Dependent Cushing Syndrome: When Inferior Petrosal Sinus Sampling Is Not Needed

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