FRI214 Adrenal Adenoma With Biochemical Findings Suggestive Of Cushing's Disease

Disclosure: A. Calimag: None. U. Tarabichi: None. M. Ahmad: None. M. Kazi: None. Introduction: We are presenting a case of a young female with prior history of multiple endocrinopathies presenting with a left adrenal adenoma with biochemical findings suggestive of Cushing's disease. Case Presentation: A 22-year-old female with a history of Type 1 Diabetes Mellitus was found to have a left adrenal adenoma 2.8 cm on CT. Absolute washout of 85 % and a relative washout of 63%, having 12 Hounsfield units (HU) on the non-contrast phase, findings suggestive of a benign adenoma. Further work up including 1 mg Dexamethasone suppression test (DST) showed unsuppressed plasma ACTH 17 pg/ml and total cortisol 9.4 mcg/dL. 8 mg DST showed ACTH 12 pg/ml, AM cortisol 8.8 mcg/dL, and Dexamethasone 991 ng/dl. Late night salivary cortisol 0.07 ug/dl, and 0.09 ug/dl, 24 hr urine cortisol 40.7. Other labs showed Aldosterone level was normal at 6.7, Renin level was also normal at 1.1. 24 hr urine catecholamines were Norepinephrine 35 mcg/24 hr, Epinephrine 3.9 mcg/24 hr, while urine Metanephrine level was <0.24, and normetanephrine level at 0.34. TSH 1.2mcU/ml. One day prior to surgery ACTH level was suppressed at 2.1 pg/ml drawn from a different lab. MRI of the Pituitary showed a slightly enlarged pituitary gland with uniform contrast enhancement and no definite lesion. The patient underwent a laparoscopic left adrenalectomy. Pathology showed an adrenal cortical neoplasm consistent with adrenal cortical adenoma, with no significant cytologic atypia, mitotic activity, or necrosis. Immunoperoxidase stain, the tumor is positive for inhibin and negative for PAX8. Post-op she developed adrenal insufficiency which was treated with hydrocortisone. The follow-up cortisol level was 11.3 mcg/dL when the patient was off hydrocortisone. Discussion: In this case, the biochemical exam showed elevated cortisol with ACTH not fully suppressed at both 1 mg and 8 mg DST which was done twice, and normal 24-hour urine cortisol. Determining whether this is adrenal vs pituitary mediated was one of the clinical dilemmas of this case. Initially, the patient’s ACTH was unsuppressed however the day before surgery ACTH was suppressed and the patient’s cortisol level normalized after the left adrenalectomy. Immunoassays for ACTH levels may occasionally be susceptible to analytical errors. ((1-2)) There are several case series and studies mentioning assay interference when using Immulite Assay versus Cobas ACTH assay. ((1-2)) Therefore, it is important to analyze clinical findings and biochemical testing and if lab tests are discordant, recheck using a different analytical platform in a different lab or an alternate ACTH assay to confirm ACTH levels. ((1-2))References: 1. Yang YY et al A Pitfall of Falsely Elevated ACTH: A Case Report and Literature Review. Journal of Investigative Medicine High Impact Case Reports. 2022 Jun 2. Donegan DM et al Corticotropin hormone assay interference: a case series. Clinical Biochemistry. 2019 Jan Presentation: Friday, June 16, 2023