Chronic electrolyte imbalance tied to ectopic Cushing’s in woman

Ectopic Cushing’s greatly increases risk for patients with small-cell lung cancer

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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An 81-year-old woman being treated for a severe and persistent electrolyte imbalance was found to have a tumor in her lung which eventually led to her diagnosis of ectopic Cushing’s syndrome, according to a case report.

Electrolytes are minerals in body fluids that carry an electric charge and are vital for many functions. An imbalance occurs when certain mineral levels are too high or too low in the blood.

The woman showed excess cortisol levels due to a lung tumor producing the adrenocorticotropic hormone (ACTH), which confirmed her ectopic Cushing’s diagnosis.

Ectopic Cushing’s syndrome is a rare form caused by an ACTH-producing tumor found outside the pituitary gland. Lung tumors account for about 50% of these cases, with small-cell lung cancer (SCLC) being a common type.

“This case, in particular, highlights the importance of seeking alternative explanations for common electrolyte disturbances, particularly when they don’t resolve promptly,” scientists wrote in the case study “Adrenocorticotropin-Dependent Ectopic Cushing’s Syndrome: A Case Report,” which was published in the journal Cureus.

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‘Prompt diagnosis and management are crucial’ in ectopic Cushing’s

“Prompt diagnosis and management are crucial in [ectopic Cushing’s], highlighting the importance of physician awareness and early recognition of this syndrome,” they noted.

Cushing’s syndrome is characterized by high cortisol levels, or hypercortisolism, which leads to symptoms such as weight gain and mood changes.

Cushing’s disease, a common form of this syndrome, is caused by mostly benign tumors in the brain’s pituitary gland, which produces greater amounts of the cortisol-controlling ACTH. Rising levels of this hormone signal the adrenal glands, sitting atop the kidneys, to produce cortisol in excessive amounts.

In the report, a group of researchers in Portugal described the case of woman, who was found to have ectopic Cushing’s associated with a SCLC after experiencing gastrointestinal issues and a severe electrolyte imbalance in the blood.

The woman, who had diabetes, had experienced lack of energy, nausea, vomiting, and diarrhea for three days and was unable to control her blood sugar levels with appropriate medication for the past week. She also had a history of high blood pressure, abnormal levels of fatty molecules in the blood, and a depressive disorder.

She was admitted to the hospital due to an acute electrolyte imbalance after she reportedly self-medicated with higher doses of metformin, a diabetes medication, for uncontrolled levels of blood sugar, or glucose.

Detected electrolyte abnormalities included lower-than-normal levels of potassium, chloride, calcium, phosphate, and magnesium.

Her physical examination was unremarkable, and blood work confirmed the electrolyte imbalances. Her kidney function was found to be normal and no signs of liver damage were detected.

This case, in particular, highlights the importance of seeking alternative explanations for common electrolyte disturbances, particularly when they don’t resolve promptly.

Patient received IV fluids, potassium, magnesium

“Considering the possible relationship between the electrolyte disorder and the gastrointestinal presentation, the patient was given intravenous (IV) fluids and received potassium and magnesium replacement therapy,” the researchers wrote.

However, her electrolyte deficiency persisted after 48 hours of treatment, and further testing was conducted to determine the cause of her condition. Her blood potassium and glucose levels also did not respond to appropriate treatment aiming to increase them.

Lab work showed elevated levels of parathyroid hormone, which controls blood calcium levels, vitamin D deficiency, and apparent ACTH-dependent hypercortisolism. She also had high levels of potassium and glucose in her urine.

A dexamethasone suppression test, commonly used to diagnose Cushing’s, showed a lack of change in her elevated cortisol levels.

In healthy people, administering dexamethasone, a lab-made steroid similar to cortisol, suppresses ACTH production, reducing cortisol levels. However, ACTH-producing tumors do not respond to dexamethasone, and cortisol levels remain high, indicating the presence of Cushing’s.

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Whole-body CT scan shows suspicious mass in left lung

Brain imaging scans did not show any abnormalities in the pituitary gland, but a whole-body CT scan showed a suspicious mass in her left lung, and a biopsy confirmed it to be a SCLC. Lesions in the liver and adrenal glands were also detected in the scan, suggesting potential cancer spreading.

The woman was referred to the cancer department, but she was not given chemotherapy right away, as hypercortisolism increases the risk for infections. She was treated with Metopirone (metyrapone), a cortisol-lowering medication, which led to a reduction in cortisol and normalized her potassium levels.

A subsequent positron emission tomography scan, however, confirmed the cancer had spread, with metastasis also found in the bone. Despite her cortisol levels being under control, her condition worsened and she died one month after the diagnosis.

“SCLC patients with [ectopic Cushing’s] have a poorer prognosis than those without [ectopic Cushing’s], with a life expectancy of only three to six months,” the researchers wrote.

This case highlights that “clinicians should be aware of [ectopic Cushing’s] and its frequent subclinical presentation in order to initiate the diagnostic workup as soon as suspicion arises,” the researchers concluded.