Outcome of CRH stimulation test and overnight 8 mg dexamethasone suppression test in 469 patients with ACTH-dependent Cushing's syndrome

Subtyping of Cushing's Syndrome: A Step Ahead

Cushing's Syndrome (CS) is a rare disease due to chronic endogenous cortisol secretion. In recent years, new developments have broadened the spectrum of differential diagnosis, traditionally categorized as adrenocorticotropic hormone (ACTH)-dependent and ACTH-independent forms. Moreover, increased awareness of the detrimental effects of cortisol on cardiometabolic health and the risk of cardiovascular events lead to increased diagnosis of mild forms, especially in the context of adrenal incidentalomas.This review provides an up-to-date narrative of the most recent literature regarding the challenges of CS diagnosis. After the description of the diagnostic tools available, the functional non-neoplastic hypercortisolism (formerly known as pseudo-Cushing state) is characterized, followed by the subtyping of the different conditions of hypercortisolism, including the differential diagnosis of ACTH-dependent forms and the management of adrenal hypercortisolism, with peculiar attention to the new genetic classification of adrenal CS, mild autonomous cortisol secretion, and bilateral adrenal adenomas.

Subclinical Cushing's Disease with High-Molecular-Weight Forms of Adrenocorticotropic Hormone Production

Production of the high-molecular-weight forms of adrenocorticotropic hormone (big-ACTH) has been reported in a small number of ectopic ACTH syndrome and ACTH-producing pituitary macroadenoma. However, perioperative changes in big-ACTH in patients with subclinical Cushing's disease have not been reported. A 63-year-old woman presented 25 × 20 × 20-mm-sized macroadenoma in the pituitary gland. Her early morning plasma ACTH and cortisol levels were 111 pg/mL and 11.6 μg/dL, respectively. Cushingoid features and diurnal variation in plasma cortisol levels were not observed. The patient's urinary free cortisol (UFC) was 59.3 μg/day. The corticotropin-releasing hormone (CRH) test showed that plasma ACTH levels were 1.5 times higher than the preload value. The overnight dexamethasone suppression test (DST) showed that the plasma cortisol level was not suppressed by 0.5 mg of dexamethasone (DEX) but was suppressed by 8 mg of DEX. Inferior pyramidal sinus sampling was consistent with Cushing's disease. Taken together, the patient was clinically diagnosed with subclinical Cushing's disease caused by an ACTH-producing pituitary adenoma. Endoscopic transsphenoidal adenomectomy was performed. In the postoperative CRH test, plasma ACTH levels showed six-fold increase. The postoperative DST showed cortisol suppression at 0.5 mg of DEX. The UFC levels decreased to 35.1 μg/day. Pituitary contrast-enhanced MRI revealed no residual tumor, and plasma ACTH and cortisol levels remained within normal ranges. Gel filtration of preoperative and postoperative plasma ACTH was performed, and a high molecular weight fraction of ACTH was detected, which markedly decreased postoperatively. The absence of Cushingoid features and the lack of significant cortisol hypersecretion in this case were thought to be due in part to big-ACTH, which has low bioactivity. By careful evaluation of laboratory and clinical findings, we identified it as a big-ACTH-producing adenoma. This is the first report of a case in which the big-ACTH transition was observed perioperative and is a valuable case.

Corticotropin-releasing hormone test predicts the outcome of unilateral adrenalectomy in primary bilateral macronodular adrenal hyperplasia

PURPOSE

Primary bilateral adrenal hyperplasia (PBMAH) is associated with hypercortisolism and a heterogeneous clinical expression in terms of cortisol secretion and related comorbidities. Historically, treatment of choice was bilateral adrenalectomy (B-Adx); however, recent data suggest that unilateral adrenalectomy (U-Adx) may be an effective alternative. For the latter, factors predicting the postsurgical outcome (e.g., biochemical control) have not been identified yet.

METHODS

PBMAH patients undergoing U-Adx for overt Cushing's syndrome (CS) in two tertiary care centers were retrospectively analysed. Remission was defined as a normalization of urinary free cortisol (UFC) without the need for medical treatment. The potential of hCRH test as a predictor of U-Adx outcome was evaluated in a subgroup.

RESULTS

23 patients were evaluated (69% females, mean age 55 years). Remission rate after U-Adx was 74% at last follow up (median 115 months from UAdx). Before U-Adx, a positive ACTH response to hCRH (Δ%ACTH increase > 50% from baseline) was associated with higher remission rates.

CONCLUSIONS

Three of four patients with PBMAH are surgically cured with U-Adx. Pre-operative hCRH testing can be useful to predict long-term remission rates.

Utility of Simple and Non-Invasive Strategies Alternative to Inferior Petrosal Sinus Sampling and Peripheral CRH Stimulation in Differential Diagnosis of ACTH-Dependent Cushing Syndrome

We aimed to evaluate the utility of simple, cost-effective, and non-invasive strategies alternative to BIPSS and peripheral CRH stimulation in differential diagnosis of ACTH-dependent CS. First, we performed ROC analysis to evaluate the performance of various tests for differential diagnosis of ACTH-dependent CS in our cohort (CD, n=76 and EAS, n=23) and derived their optimal cut-offs. Subsequently, combining various demographic (gender), clinical (hypokalemia), biochemical (plasma ACTH, HDDST, peripheral CRH stimulation) and imaging (MRI pituitary) parameters, we derived non-invasive models with 100% PPV for CD. Patients with pituitary macroadenoma (n=14) were excluded from the analysis involving non-invasive models. Relative percent ACTH (AUC: 0.933) and cortisol (AUC: 0.975) increase on peripheral CRH stimulation demonstrated excellent accuracy in discriminating CD from EAS. Best cut-offs for CD were plasma ACTH<97.3 pg/ml, HDDST≥57% cortisol suppression, CRH stimulation≥77% ACTH increase and≥11% cortisol increase. We derived six models that provided 100% PPV for CD and precluded the need for BIPPS in 35/85 (41.2%) patients with ACTH-dependent CS and no macroadenoma (in whom BIPSS would have otherwise been recommended). The first three models included basic parameters and avoided both peripheral CRH stimulation and BIPSS in 19 (22.4%) patients, while the next three models included peripheral CRH stimulation and avoided BIPSS in another 16 (18.8%) patients. Using simple and non-invasive alternative strategies, BIPSS can be avoided in 41% and peripheral CRH stimulation in 22% of patients with ACTH-dependent CS and no macroadenoma; such patients can be directly referred for a pituitary surgery.

Ovine CRH Stimulation and 8 mg Dexamethasone Suppression Tests in 323 Patients With ACTH-Dependent Cushing's Syndrome

CONTEXT

Determining the etiology of adrenocorticotropin (ACTH)-dependent Cushing's syndrome (CS) is often difficult. The gold standard test, inferior petrosal sinus sampling (IPSS), is expensive and not widely available.

OBJECTIVE

Evaluate the performance of the corticotropin-releasing hormone stimulation test (CRH-ST) and the 8 mg high-dose dexamethasone suppression test (HDDST) in distinguishing Cushing's disease (CD) from ectopic ACTH syndrome (EAS).

METHODS

Retrospective review in a tertiary referral center. A total of 323 patients with CD or EAS (n = 78) confirmed by pathology or biochemical cure (n = 15) in 96% underwent CRH-ST and HDDST performed between 1986 and 2019. We calculated test sensitivity (Se), specificity (Sp), positive predictive value (PPV), negative predictive value, and diagnostic accuracy (DA) for the diagnosis of CD, and determined optimal response criteria for each test, alone and in combination.

RESULTS

The CRH-ST performed better than the HDDST (DA 91%, 95% CI 87-94% vs 75%, 95% CI 69-79%). Optimal response criteria were a ≥40% increase of ACTH and/or cortisol during the CRH test and a ≥69% suppression of cortisol during the HDDST. A ≥40% cortisol increase during the CRH test was the most specific measure, PPV 99%. Seventy-four percent of subjects had concordant positive CRH test and HDDST results, yielding Se 93%, Sp 98%, DA 95%, and PPV 99%, with a pretest likelihood of 85%. A proposed algorithm diagnosed 64% of patients with CD with near perfect accuracy (99%), obviating the need for IPSS.

CONCLUSION

CRH is a valuable tool to correctly diagnose the etiology of ACTH-dependent CS. Its current worldwide unavailability impedes optimal management of these patients.

Bilateral inferior petrosal sinus sampling: Procedural data from a German single-center study

PURPOSE

To assess radiation exposure and diagnostic performance of bilateral inferior petrosal sinus sampling for the distinction of pituitary and ectopic adrenocorticotropin-dependent Cushing's syndrome.

MATERIALS AND METHODS

Procedural data of bilateral inferior petrosal sinus procedures were retrospectively evaluated. The analysis included the patients' clinical and demographic data, procedural radiation exposure, and complication rates, sampling results, clinical course of the patients, and calculation of diagnostic performance data.

RESULTS

The cases of 46 patients diagnosed with adrenocorticotropin-dependent Cushing's syndrome were evaluated. Bilateral inferior petrosal sinus sampling was successfully performed in 97.8 % of the cases. The overall median procedure-related fluoroscopy time was 7.8 min. (range 3.2-36.2 min.), and the median procedural dose area product was 11.9 Gy*cm2 (range 2.1-73.7 Gy*cm2). Radiation doses due to digital subtraction angiography series for visualization of the inferior petrosal sinus were 3.6 Gy*cm2 (range 1.0-18.1 Gy*cm2). Radiation doses due to fluoroscopy had a higher impact on the overall radiation exposure and were significantly influenced by the patients' habitus. The sensitivity, specificity, and positive and negative predictive values were 84 %, 100 %, 100 %, and 72 % before stimulation with corticotropin-releasing hormone, and 97 %, 100 %, 100 %, and 93 % after stimulation. Concordance between magnetic resonance imaging studies and bilateral inferior petrosal sinus sampling results was only found in 35.6 % of the cases. The periprocedural complication rate was 2.2 %, with one patient experiencing vasovagal syncope during catheterization.

CONCLUSION

Bilateral inferior petrosal sinus sampling is a safe procedure with high technical success rates und excellent diagnostic performance. The procedure-related radiation exposure shows large variations and depends on the complexity of cannulation as well as the patients' habitus. Fluoroscopy accounted for the largest proportion of radiation exposure. Acquisition of digital subtraction angiography series for the verification of correct catheter placement appears justified.

KEY POINTS

· Bilateral inferior petrosal sinus sampling with CRH stimulation provides high diagnostic performance in the distinction of pituitary and ectopic Cushing's syndrome.. · The associated radiation exposure is not negligible and is significantly influenced by the use of fluoroscopy and the patients' habitus.. · Digital subtraction angiography contributes less to the overall radiation dose and appears justified for the verification of correct catheter placement..

CITATION FORMAT

· Augustin A, Detomas M, Hartung V et al. Bilateral inferior petrosal sinus sampling: Procedural data from a German single-center study. Fortschr Röntgenstr 2023; 195: 1009 - 1017.

Bilateral inferior petrosal sinus sampling: validity, diagnostic accuracy in lateralization of pituitary microadenoma, and treatment in eleven patients with Cushing's syndrome - a single-center retrospective cohort study

BACKGROUND

This single-center retrospective cohort study aimed to describe the findings and validity of Bilateral inferior petrosal sinus sampling (BIPSS) in the differential diagnosis of patients with ACTH-dependent Cushing's syndrome (CS).

METHODS

Eleven patients underwent BIPSS due to equivocal biochemical tests and imaging results. Blood samples were taken from the right inferior petrosal sinus (IPS), left IPS, and a peripheral vein before and after stimulation with desmopressin (DDAVP). ACTH and prolactin levels were measured. The diagnosis was based on the ACTH ratio between the IPS and the peripheral vein. Also, lateralization of pituitary adenoma in patients with Cushing's disease (CD) was predicted. No significant complications were observed with BIPSS.

RESULTS

Based on the pathology report, eight patients had CD, and three had ectopic ACTH syndrome (EAS). Unstimulated BIPSS resulted in a sensitivity of 87.5%, specificity of 100%, PPV of 100%, NPV of 75%, and accuracy of 91%. Stimulated BIPSS resulted in a sensitivity of 100%, specificity of 100%, PPV of 100%, NPV of 100%, and accuracy of 100%. However, pituitary magnetic resonance imaging (MRI) had a lower diagnostic accuracy (sensitivity:62.5%, specificity:33%, PPV:71%, NPV:25%, accuracy:54%). BIPSS accurately demonstrated pituitary adenoma lateralization in 75% of patients with CD.

CONCLUSIONS

This study suggests that BIPSS may be a reliable and low-complication technique in evaluating patients with ACTH-dependent CS who had inconclusive imaging and biochemical test results. The diagnostic accuracy is improved by DDAVP stimulation. Pituitary adenoma lateralization can be predicted with the aid of BIPSS.

Osteoporosis as the First Sign of Cushing's Disease in a Thin 16-Year-Old Boy-A Case Report

Cushing's disease (CD) is an extremely rare diagnosis in children. In this report, we present the case of an almost 16-year-old, short and thin boy with CD, the first symptoms of which were spinal pain and vertebral fractures as a result of osteoporosis. In light of his growth retardation and short stature, the boy underwent diagnostics, which excluded growth hormone (GH) deficiency, hypothyroidism and celiac disease. Finally, based on cortisol profile results, dexamethasone suppression tests and bilateral sampling during catheterization of the inferior petrosal sinuses, CD was diagnosed.

Pitfalls in the Diagnosis and Management of Hypercortisolism (Cushing Syndrome) in Humans; A Review of the Laboratory Medicine Perspective

Biochemical confirmation of a diagnosis of hypercortisolism (Cushing syndrome) is vital to direct further investigations, especially given the overlap with non-autonomous conditions, such as pseudo-Cushing, and the morbidity associated with missed diagnoses. A limited narrative review was performed focusing on the laboratory perspective of the pitfalls of making a biochemical diagnosis of hypercortisolism in those presenting with presumed Cushing syndrome. Although analytically less specific, immunoassays remain cheap, quick, and reliable in most situations. Understanding cortisol metabolism can help with patient preparation, specimen selection (e.g., consideration of urine or saliva for those with possible elevations of cortisol binding globulin concentration), and method selection (e.g., mass spectrometry if there is a high risk of abnormal metabolites). Although more specific methods may be less sensitive, this can be managed. The reduction in cost and increasing ease of use makes techniques such as urine steroid profiles and salivary cortisone of interest in future pathway development. In conclusion, the limitations of current assays, particularly if well understood, do not impede diagnosis in most cases. However, in complex or borderline cases, there are other techniques to consider to aid in the confirmation of hypercortisolism.