Test Found Useful for Diagnosing Cushing’s During Pregnancy

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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The desmopressin stimulation test can be useful to diagnose Cushing’s during pregnancy, a time when its identification may be particularly challenging due to the hormonal changes these women experience, a new case report says.

The report, “Desmopressin Stimulation Test in a Pregnant Patient with Cushing’s Disease,” was published in the journal AACE Clinical Case Reports.

Cushing’s disease is caused by a tumor in the pituitary gland, located in the brain. The tumor prompts the gland to produce and release high levels of a signaling molecule called adrenocorticotropic hormone (ACTH), which in turn prompts the adrenal glands, located just above the kidneys, to produce excessive amounts of the stress hormone cortisol. High cortisol levels are ultimately the cause of Cushing’s symptoms.

Diagnosing Cushing’s commonly involves looking for evidence of elevated ACTH levels. During pregnancy, however, ACTH levels naturally rise, making it hard to diagnose the condition in someone who is pregnant.

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Here, scientists in Thailand described the case of a 27-year-old woman who was diagnosed with Cushing’s disease while pregnant with the help of the desmopressin stimulation test.

When she was nine weeks pregnant, the woman had an appearance that was typical of Cushing’s (e.g., purple stretch marks, bruising) and muscle weakness that had lasted for two months.

She had a history of high blood pressure and abnormal blood sugar levels, and in the two years before becoming pregnant, she had gained 20 kg (around 44 lbs).

Laboratory tests revealed her cortisol levels were higher than normal, prompting a suspicion of Cushing’s disease. Initial imaging of the pituitary gland revealed mild structural changes, but no signs of a clear tumor.

Clinicians then conducted the desmopressin stimulation test when she was 14 weeks pregnant. Put simply, this test involves administering desmopressin, a synthetic version of a hormone naturally found in the body that promotes the production of ACTH in people with Cushing’s disease, but not in those with other diseases that cause cortisol levels to rise.

Results showed that 15 minutes following desmopressin administration, her ACTH levels increased by 70%. For context, in nonpregnant people, an increase of at least 35% is usually sufficient to confirm a Cushing’s diagnosis.

Additional imaging tests eventually identified the tumor, which was surgically removed when the patient was 18 weeks pregnant. She was placed on cortisol supplements to prevent hormone levels from dipping too low and was given medications to manage blood pressure and blood sugar levels.

After 38 weeks of pregnancy, she gave birth to a boy who was somewhat small for his gestational age, but otherwise healthy. After delivery, her high blood pressure and abnormal blood sugar levels normalized.

A year later, the patient became pregnant again and delivered another baby after an uneventful pregnancy, with no signs of Cushing’s disease. Two years after surgery, she stopped taking cortisol supplements.

“The results from the desmopressin stimulation test and the pituitary MRI … suggested the diagnosis of [Cushing’s disease], which subsequently led to successful treatment,” the researchers wrote, adding that this test “may serve as a useful test to diagnose [Cushing’s disease] even in the context of pregnancy.”