Desmopressin test detects residual tumor after Cushing’s surgery: Case
Results helped in treatment of women, 26, after standard testing failed
A diagnostic test using desmopressin, an artificial form of a naturally occurring hormone, successfully detected a residual pituitary tumor after surgery to treat a woman with cyclic Cushing’s disease when standard tests failed, a case study reports.
The researchers noted that the very nature of cyclic Cushing’s disease — a form of Cushing’s in which cortisol levels and disease activity rise and fall over time — makes it a challenge to treat patients with it, such as the U.K. woman in her 20s described in this report.
“The [desmopressin test] may be particularly useful during periods of low disease activity in cyclic [Cushing’s], as other dynamic tests used to diagnose [Cushing’s] may be uninterpretable in this setting,” the researchers wrote. “Postoperatively, the [desmopressin] may be useful to confirm successful tumor resection and to monitor for [Cushing’s disease] recurrence.”
The case study, “Using the Desmopressin Stimulation Test to Assess for Residual Tumor in Cushing Disease With Cyclic Hypercortisolism,” was published in JCEM Case Reports.
In Cushing’s disease, excess levels of the signaling molecule adrenocorticotropic hormone (ACTH), secreted by tumors in the pituitary gland, drive the adrenal glands, which sit atop the kidneys, to produce too much cortisol. Over time, excessive levels of cortisol in the bloodstream, known as hypercortisolism, give rise to disease symptoms.
Surgically removing the pituitary tumors in a procedure called a transsphenoidal adenomectomy — typically the first-line treatment for Cushing’s disease — leads to remission in as many as 90% of cases, with recurrence rates at about 20%.
With cyclic Cushing’s, tests may incorrectly suggest remission after surgery
Cyclic Cushing’s, marked by cortisol levels that rise and fall over time, poses a challenge to diagnostic testing and postoperative monitoring, the researcher noted. Specifically, when patients undergo testing during times of low cortisol, the results may indicate no Cushing’s, or falsely suggest remission after surgery.
A desmopressin stimulation test, or DST, involves administering an artificial form of the hormone, which causes ACTH and cortisol levels to increase, specifically in people with Cushing’s disease.
To highlight the test’s utility to detect a residual tumor after surgery, in which remission was indicated, the researchers here described the case of a 26-year-old woman with signs of cyclic Cushing’s disease.
The woman had developed symptoms of Cushing’s that included irregular periods, weight gain, facial rounding, a buffalo hump, stretch marks, and hair loss, alongside worsening fatigue, anxiety, depression, and acne. Lab tests confirmed hypercortisolism, and an MRI revealed a small pituitary tumor — all consistent with Cushing’s disease.
Due to surgical delays caused by the COVID-19 pandemic, a transsphenoidal adenomectomy took place six months later, in which surgeons removed an ACTH-positive pituitary tumor.
Blood tests showed a marked drop in the woman’s cortisol levels. At that point, she began hydrocortisone replacement therapy to maintain her cortisol levels in the normal range.
When her blood cortisol normalized eight months later, the hydrocortisone was stopped. Her acne and menstrual irregularities resolved, and her weight stabilized without any reduction, though hair loss continued.
Desmopressin test showed over 100% increase in woman’s ACTH levels
Ten months after surgery, the woman’s anxiety and depression worsened to the point where she had difficulties at work. Further testing confirmed the return of hypercortisolism, and an MRI suggested a small residual pituitary tumor.
She then sought a second opinion, which showed the same residual pituitary tumor on MRI scans. Still, the woman’s salivary and blood cortisol levels were undetectable, with low to normal ACTH and urine-free cortisol. Moreover, there were no signs of adrenal insufficiency, which occurs when the adrenal glands don’t make enough of certain hormones.
“These results … were in stark contrast to the hypercortisolism confirmed [one] month earlier, raising suspicion for [bleeding or impaired blood flow] of residual tumor tissue or cyclic [Cushing’s],” the team wrote.
Upon further questioning, the patient reported a previous increase and decrease in acne severity, but no clear cycling of other symptoms. Three weeks later, she underwent DST, which showed a 111% increase in ACTH and a 172% rise in cortisol, “confirming the presence of residual tumor tissue.”
Postoperative screening tests for hypercortisolism may not be reliable in cyclic [Cushing’s] since low or normal ACTH and cortisol levels can reflect either remission or low disease activity.
The patient underwent repeat transsphenoidal surgery for residual pituitary tumor, which was again confirmed as an ACTH-producing tumor. A repeat DST showed no cortisol response and a minimal ACTH increase, indicating successful tumor removal, the researchers noted.
The woman was discharged with hydrocortisone replacement to treat temporary adrenal insufficiency. She also was given desmopressin to treat a resulting postoperative arginine vasopressin (AVP) deficiency — too little of a hormone critical for regulating the body’s water balance.
Over six months, her AVP deficiency resolved, and hydrocortisone was discontinued after eight months once normal adrenal function was confirmed. The woman lost 60 pounds over three years, returning to her normal weight, and her facial rounding and buffalo hump were resolved. Her acne also improved.
Three years after surgery, she remained in remission but continued to experience persistent hair loss, diminished taste and smell, and fluctuating fatigue, anxiety, and depression, the researchers noted.
“Postoperative screening tests for hypercortisolism may not be reliable in cyclic [Cushing’s] since low or normal ACTH and cortisol levels can reflect either remission or low disease activity,” the researchers wrote.
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