A Case of Cortisol Producing Adrenal Adenoma without Phenotype of Cushing's Syndrome due to Impaired 11β-Hydroxysteroid Dehydrogenase 1 Activity

Abstract

This report concerns a case of cortisol-producing adrenocortical adenoma without the phenotype of Cushing's syndrome. A left adrenal tumor was incidentally detected in this patient. A diagnosis of adrenal Cushing's syndrome was based on the results of endocrinological and radiological examinations, although she showed none of the physical signs of Cushing's syndrome, glucose intolerance, hypertension or dyslipidermia. After a successful laparoscopic left adrenalectomy, the pathological diagnosis was adrenocortical adenoma. Slow tapering of glucocorticoids was needed to prevent adrenal insufficiency after surgery, and the plasma ACTH level remained high even though the serum cortisol level had reached the upper limit of the normal range. Further examination showed a urinary THF + allo-THF/THE ratio of 0.63, which was lower than that of control (0.90 ± 0.13, mean ± SD). Serum cortisol/cortisone ratios after the cortisone acetate administration were also decreased, and the serum half-life of cortisol was shorter than the normal range which has been reported. These findings indicated a partial defect in 11β-hydroxysteroid dehydrogenase 1 (11β-HSD1) activity, which converts cortisone to cortisol. Our case suggests that a change in 11β-HSD1 activity results in inter-individual differences in glucocorticoid efficacy.