Introduction : Cushing syndrome is a rare condition resulting from excess cortisol.Cushing Syndrome (CS) can be ACTH-independent or ACTH-dependentwith the latter dividing intoCushing disease (CD) or ectopic. The first line treatment of CD is transsphenoidal surgery (TSS). Remission rates after TSS vary from 60%-90% depending on tumor size, surgical expertise and length of follow up. Hypercortisolism persisting post-operatively indicatessurgical failure. In some cases, serum cortisol levelsundergo a delayed decline after surgery.
Case(s) Description : We report a 50-year-old female presenting with fatigue, weight gain and a dorsocervical fat pad. A 1mg dexamethasone suppression test revealed a morning cortisol of 9.4mcg/dL (< 1.8mcg/dL),and a midnight salivary test was 0.37 mcg/dL (< 0.145mcg/dL) confirming the presence of hypercortisolism. The morning cortisol level was elevated, 29.6mcg/dL (4-22mcg/dL), with an inappropriately normal ACTH, 31 pg/mL (6-50 pg/mL),indicating an ACTH-dependent CS. Brain MRI showed noevidence of a pituitary mass. The patient underwent inferior petrosal sinus sampling (IPSS)indicatingleft lateralization with theinferior petrosal sinus:peripheral ACTH (IPS:P) ratio of 10.6 pre-desmopressin administration (IPS:P>2) and 24.3 post-desmopressin administration (IPS:P>3). The left to right instersinus gradient was 13.25 pre-desmopressin( >1.4) and 28 post-desmopressin administration ( >1.4). The patient subsequently underwent TSS with an immediate post-operative cortisol level of 23 mcg/dL. Surgical pathology from TSS revealedbenign pituitary tissue. Three weeks later, the morning cortisol level remained elevated at 20.9 mcg/dL. There was consideration of gamma knife radiation,but this was delayed due toinsurance. Ten weeks post-TSS, repeat morning cortisol level of 8.1 mcg/dL and ACTH 9 pg/mLshowed decline. At 14 weekspost-TSS, a morning cortisol level of 3.7mcg/dL and ACTH 5.9 pg/mL finally indicatedremission of CD, andno additional treatment was necessary.
Discussion : Cortisol levels typically decline two to three days after TSS. In asmall subset of patients with CD,the decline of cortisol levels maybe delayed. Recent studies show 18% of patients with initial postoperative hypercortisolism developed delayed low or normal cortisol levels between 45 to 53 days. This persistent elevation of cortisol levels poses a significant question regarding subsequent treatment.Although prospective studies are needed, continued observationuntil cortisol levels reach their nadir at approximately 6-12 weeks p</span>ost-operation might be helpful in avoiding unnecessary treatment.
