RELIABILITY OF THE CORTICOTROPIN RELEASING HORMONE STIMULATION TEST FOR DIFFERENTIATING BETWEEN ACTH DEPENDENT AND INDEPENDENT CUSHING SYNDROME

Endogenous Cushing's syndrome during pregnancy

Endogenous Cushing's syndrome (CS) is rare during pregnancy, probably because hypercortisolism induces anovulation and infertility. To date, slightly above 200 cases have been reported in the literature. The most frequent etiology of CS diagnosed during gestation is from primary adrenal causes, namely adrenal adenomas and an entity called pregnancy-induced CS. The latter can be secondary to the aberrant adrenal expression of luteinizing hormone/human chorionic gonadotropin receptor (LHCGR) in the adrenal lesions. Diagnosis of CS during pregnancy is extremely challenging, as a consequence of the physiologic hypercortisolism normally present during pregnancy. Assessment of excess cortisol production tests should be interpreted cautiously using adapted upper limits of normal criteria for pregnant patients and a high index of suspicion is required for diagnosis. Imaging is also limited due to high risk of radiation exposure with computed tomography and teratogenicity with contrast agents. The optimal treatment strategy is surgical resection of adrenal adenoma or pituitary adenoma, ideally before 24 weeks of gestation to reduce the risk of maternal and fetal complications. In mild cases, surgery can be postponed until after delivery and treatment should focus on controlling metabolic complications of hypercortisolism, such as hypertension and dysglycemia. Maternal and fetal outcomes of excess cortisol exposure, except fetal loss, are not readily improved by successful treatment of hypercortisolism.

Dynamic testing for differential diagnosis of ACTH-dependent Cushing Syndrome: a systematic review and meta-analysis

OBJECTIVE

Diagnostic accuracy of testing currently used for the differential diagnosis of Cushing's disease (CD) vs ectopic -ACTH secretion (EAS) is difficult to interpret. The present study aimed to identify and evaluate the diagnostic accuracy of corticotropin-releasing hormone (CRH) test, desmopressin test, and high-dose dexamethasone suppression test (HDDST) when used to establish a CD or EAS diagnosis.

DESIGN

This study is a systematic review of the literature and meta-analysis.

METHODS

MEDLINE, OVID, and Web of Science databases were searched for articles published between the years 1990-2021. Articles included described at least one test(s) (CRH, desmopressin, or HDDST) and the diagnostic reference standard(s) (histopathology, petrosal sinus sampling, surgical remission, imaging, and long-term follow-up) used to establish a CD or EAS diagnosis.

RESULTS

Sixty-two studies were included: 43 reported the use of HDDST, 32 CRH test, and 21 desmopressin test. CRH test was found to have the highest sensitivity in detecting CD (ACTH 86.9%, 95% confidence interval [CI] 82.1-90.6, cortisol 86.2%, 95%CI 78.3-91.5) and the highest specificity in detecting EAS (ACTH 93.9%, 95%CI 87-98.3, cortisol 89.4%, 95%CI 82.8-93.7). This resulted in a high diagnostic odds ratio (58, 95%CI 43.25-77.47), large area under the curve, and a receiver-operating characteristic (ROC) of 0.934. The diagnostic accuracy of HDDST and desmopressin test(s) was lower than that of the CRH test.

CONCLUSION

The meta-analysis indicates that a patient with a positive ACTH response after a CRH test is highly likely to have CD. Further studies analysing role of dynamic testing in addition to imaging are needed.

Coexistence of Cushing Disease With a Solitary Adrenocorticotrophic Hormone-Dependent Adrenal Adenoma

Objective

We report a 49-year-old woman who had minimal features of Cushing syndrome and an incidentally discovered adrenal adenoma. She was subsequently diagnosed with pituitary-dependent Cushing syndrome.

Methods

Laboratory and imaging studies including serum cortisol, plasma adrenocorticotrophic hormone (ACTH), high dose dexamethasone test, corticotropin-releasing hormone test, computed tomography (CT) scan, and magnetic resonance imaging were performed.

Results

A 49-year-old woman was admitted for urosepsis. An abdominal CT scan performed during the urosepsis workup showed a 2.7-cm right adrenal adenoma. She denied any abdominal striae or other symptoms. Physical examination showed normal vital signs, minimal facial fullness without central obesity, and striae. Laboratory results were as follows: 24-hour-urine cortisol 294 μg (reference 4.0-50.0), midnight serum cortisol 23.0 μg/dL (reference < 7.5), and plasma ACTH level 39 pg/mL (reference 5-27). A corticotropin-releasing hormone stimulation test showed >20% rise in serum cortisol and >35% rise in ACTH levels. A pituitary magnetic resonance image showed a 5 mm pituitary lesion. The patient underwent transsphenoidal pituitary surgery, which confirmed an ACTH-secreting lesion. Postoperatively, she required hydrocortisone replacement for the next 10 months. A follow-up adrenal CT performed 6 months later showed a decrease in the size of the adrenal adenoma (1.8 cm).

Conclusion

This case highlights the importance of recognizing the coexistence of ACTH-dependent Cushing disease with an adrenal adenoma and partial ACTH dependency of the adrenal adenoma.