Patients with Cushing disease have an increased risk for new-onset autoimmune disease in the 3 years after surgical remission, according to a new retrospective study published on February 20 in Annals of Internal Medicine.
Outcomes for patients with Cushing disease were compared against those with nonfunctioning pituitary adenomas (NFPAs). New-onset autoimmune disease occurred in 10.4% with Cushing disease and 1.6% among patients with NFPA (hazard ratio, 7.80; 95% CI, 2.88-21.10).
“Understanding and recognizing new and recurrent autoimmune disease in this setting is important to avoid misclassifying such patients with glucocorticoid withdrawal syndrome, which could result in failure to treat underlying autoimmune disease, as well as erroneous diagnosis of steroid withdrawal cases,” wrote Dennis Delasi Nyanyo of Massachusetts General Hospital and Harvard Medical School, Boston, and colleagues.
Given the general population’s annual incidence of major autoimmune diseases, estimated at about 100 cases per 100,000 people, and the 3-year incidence of 10.4% found in this study’s cohort, “our findings suggest that Cushing disease remission may trigger development of autoimmune disease,” the authors wrote.
Monitor Patients With Family History of Autoimmune Disease?
The study results were not necessarily surprising to Anthony P. Heaney, MD, PhD, an endocrinologist and professor of medicine at the University of California, Los Angeles, because past research has raised similar questions. The authors’ suggestion that the rapid postsurgical drop in cortisol that occurs as a result of treating Cushing disease becomes some sort of autoimmune trigger is interesting but remains speculative, Dr. Heaney pointed out.
If future evidence supports that possibility, “it would suggest, in terms of managing those patients in the postoperative setting, that there may be some merit to giving them higher concentrations of glucocorticoids for a short period of time,” Dr. Heaney said, thereby bringing their levels down more gradually rather than taking them off a cliff, in a sense. Or, if more evidence bears out the authors’ hypothesis, another approach might be treating patients with medicine to bring down the cortisol before surgery, though there are challenges to that approach, Dr. Heaney said.
At the same time, those who developed new autoimmune disease remain a small subset of patients with Cushing disease, so such approaches may become only potentially appropriate to consider in patients with risk factors, such as a family history of autoimmune disease.
The researchers conducted a retrospective chart review of adult patients who underwent transsphenoidal surgery for either Cushing disease or NFPA at Massachusetts General Hospital between 2005 and 2019.
The study involved 194 patients with Cushing disease who had postsurgical remission and at least one follow-up visit with a pituitary expert and 92 patients with NFPA who were matched to patients with Cushing disease based on age and sex. The authors regarded autoimmune disease diagnosed within 36 months of the surgery to be temporally associated with Cushing disease remission. Among the autoimmune diseases considered were “rheumatoid arthritis, Sjögren syndrome, systemic lupus erythematosus, autoimmune thyroiditis, celiac disease, psoriasis, vitiligo, autoimmune neuropathy, multiple sclerosis, myasthenia gravis, and ulcerative colitis.”
Patients differed in average body mass index and tumor size, but family history of autoimmune disease was similar in both groups. Average BMI was 34.5 in the Cushing group and 29.5 in the NFPA group. Average tumor size was 5.7 mm in the Cushing group and 21.3 mm in the NFPA group.
Before surgery, 2.9% of patients with Cushing disease and 15.4% of patients with NFPA had central hypothyroidism, and 8% in the Cushing group and 56.8% in the NFPA group had hyperprolactinemia. Central adrenal insufficiency occurred in 11% with NFPA and in all with Cushing disease, by definition.
After surgery, 93.8% in the Cushing group and 16.5% in the NFPA group had adrenal insufficiency. In addition, patients with Cushing disease had lower postsurgical nadir serum cortisol levels (63.8 nmol/L) than those with NFPA (282.3 nmol/L).
Of the 17 patients with Cushing disease — all women — who developed autoimmune disease within 3 years, 6 had a personal history of autoimmune disease and 7 had a family history of it. In addition, 41.2% of them had adrenal insufficiency when they developed the new autoimmune disease. Among the diseases were six autoimmune thyroiditis cases, three Sjögren syndrome cases, and two autoimmune seronegative spondyloarthropathy.
Dr. Heaney said he found it interesting that more than half of the new autoimmune diseases in patients with Cushing disease were related to the thyroid. “In this kind of setting, where you have a patient who has been producing too much steroid over a period of time and then you take that away, it’s almost like you release a brake on the TSH [thyroid-stimulating hormone],” Dr. Heaney said. “So, there’s probably some rebound in TSH that occurs, and that could be driving the thyroiditis, to some extent, that we see in these patients.”
Only one patient with NFPA developed new-onset autoimmune disease, a woman who developed Graves disease 22 months after surgery. When the researchers excluded patients in both groups with central hypothyroidism, new-onset autoimmune disease was still significantly higher (11.4%) in the Cushing group than in the NFPA group (1.9%; HR, 7.02; 95% CI, 2.54-19.39).