Diagnostic Accuracy of Adrenal Iodine-131 6-Beta-Iodomethyl-19-Norcholesterol Scintigraphy for the Subtyping of Primary Aldosteronism

PURPOSE

To evaluate the diagnostic accuracy of the 131I-6β-iodomethyl-19-norcholesterol (NP-59) adrenal scintigraphy for the subtyping diagnosis of primary aldosteronism (PA), considering as gold standard for the diagnosis of unilateral PA (UPA), either the results of the adrenal venous sampling (AVS) or the outcome after adrenalectomy.

METHODS

A retrospective multicenter study was performed on PA patients from 14 Spanish tertiary hospitals who underwent NP-59 scintigraphy with an available subtyping diagnosis. Patients were classified as UPA if biochemical cure was achieved after adrenalectomy or/and if an AVS lateralization index > 4 with ACTH stimulation or >2 without ACTH stimulation was observed. Patients were classified as having bilateral PA (BPA) if the AVS lateralization index was ≤4 with ACTH or ≤2 without ACTH stimulation or if there was evidence of bilateral adrenal nodules >1 cm in each adrenal gland detected by CT/MRI.

RESULTS

A total of 86 patients with PA were included (70.9% (n = 61) with UPA and 29.1% (n = 25) with BPA). Based on the NP-59 scintigraphy results, 16 patients showed normal suppressed adrenal gland uptake, and in the other 70 cases, PA was considered unilateral in 49 patients (70%) and bilateral in 21 (30%). Based on 59-scintigraphy results, 10.4% of the patients with unilateral uptake had BPA, and 27.3% of the cases with bilateral uptake had UPA. The AUC of the ROC curve of the NP-59 scintigraphy for PA subtyping was 0.812 [0.707-0.916]. Based on the results of the CT/MRI and NP-59 scintigraphy, only 6.7% of the patients with unilateral uptake had BPA, and 24% of the cases with bilateral uptake had UPA. The AUC of the ROC curve of the model combining CT/MRI and 59-scintigraphy results for subtyping PA was 0.869 [0.782-0.957].

CONCLUSION

The results of NP-59 scintigraphy in association with the information provided by the CT/MRI may be useful for PA subtyping. However, their diagnostic accuracy is only moderate. Therefore, it should be considered a second-line diagnostic tool when AVS is not an option.

Nonfunctioning adrenal incidentalomas with cortisol post-dexamethasone suppression test >0.9 µg/dL have a higher prevalence of cardiovascular disease than those with values ≤0.9 µg/dL

PURPOSE

To analyze the differences in the cardiometabolic profile in patients with nonfunctioning adrenal incidentalomas (NFAI) with post-dexamethasone suppression test (DST) cortisol ≤1.4 µg/dL (NFAI ≤ 1.4) and those with post-DST cortisol >1.4 µg/dL (NFAI > 1.4) and between NFAI with post-DST cortisol ≤0.9 µg/dL (NFAI ≤ 0.9) and those with levels >0.9 µg/dL (NFAI > 0.9).

METHODS

Multicenter retrospective observational study of patients with NFAIs. NFAI was defined as an adrenal incidentaloma with negative hormonal study (including metanephrines, post-DST cortisol ≤1.8 µg/dL and aldosterone/renin ratio when screening was indicated). Autonomous cortisol secretion (ACS) development was defined as an NFAIs in which post-DST serum cortisol >1.8 µg/dL were evidenced during hormonal follow-up evaluation.

RESULTS

A total of 593 NFAI were included. Based on the 1.4 µg/dL threshold in the DST, most of the NFAI were classified as NFAI ≤ 1.4 (74.5%). Patients in the NFAI > 1.4 group were older than those in the NFAI ≤ 1.4 group, but there was no difference in the cardiometabolic profile after adjusting for age. A total of 69.5% of the patients had DST > 0.9 µg/dl. They were older and had a higher prevalence of cardiovascular disease than NFAI ≤ 0.9, even after adjusting by age (adjusted OR = 2.23 [1.10-4.53]). Patients in the NFAI > 1.4 group developed ACS more commonly than the NFAI ≤ 1.4 group (23.5% vs. 7.44%, P < 0.001). However, when the threshold of 0.9 µg/dL was considered, no difference was found between NFAI ≤ 0.9 and NFAI > 0.9 (P = 0.126).

CONCLUSION

The threshold of 1.4 µg/dL in the DST is useful to predict which patients with NFAI had a higher risk of ACS development during follow-up; and the threshold of 0.9 µg/dL to identify those patients with NFAI with a higher cardiovascular risk.

Accuracy of the dexamethasone suppression test for the prediction of autonomous cortisol secretion-related comorbidities in adrenal incidentalomas

PURPOSE

The aim of this study was to evaluate the diagnostic accuracy of the 1 mg dexamethasone suppression test (DST) for the prediction of autonomous cortisol secretion (ACS)-related comorbidities in patients with adrenal incidentalomas (AIs).

METHODS

This was a retrospective multicenter study. We recruited patients with AI/s ≥ 1 cm, excluding those who, during the study, were found during the extension study of an extra-adrenal cancer, with a known diagnosis of hereditary syndromes characterized by adrenal tumors, those presenting with overt hormonal excess syndromes, and those in whom the DST results were missing.

RESULTS

A total of 823 patients met the inclusion criteria. Based on the 1.8, 3.0, and 5.0 µg/dl post-DST cortisol thresholds, the prevalence of ACS was 33.5%, 13.7%, and 5.6%, respectively. The prevalence of hypertension (OR = 1.8, 95% CI = 1.3-2.4), diabetes (OR = 1.6, 95% CI = 1.2-2.2), and dyslipidemia (OR = 1.4, 95% CI = 1.0-1.9) was higher with cortisol post-DST ≥ 1.8 µg/dl; the prevalence of hypertension (OR = 2.1, 95% CI = 1.4-3.3) and diabetes (OR = 1.7, 95% CI = 1.1-2.6) was higher with values ≥ 3.0 µg/dl; and the prevalence of hypertension (OR = 2.0, 95% CI = 1.0-3.7) was higher with levels ≥ 5.0 µg/dl. However, the diagnostic accuracy of the DST for the prediction of cardiometabolic comorbidities in patients with AIs was poor, with areas under the ROC curve < 0.61.

CONCLUSIONS

The DST is a poor predictor of cardiometabolic comorbidities in patients with AIs regardless of the cortisol cut-off values applied. This finding suggests that the diagnosis of ACS should not be based solely on the results of the DST. Other clinical, metabolic, or imaging markers showing a better performance for the prediction of the development and progression of cardiometabolic comorbidities in AIs need to be identified.

Cardiometabolic profile of non-functioning and autonomous cortisol-secreting adrenal incidentalomas. Is the cardiometabolic risk similar or are there differences?

OBJECTIVE

To study the differences in the cardiometabolic profile between patients with non-functioning adrenal incidentalomas (NFAI) and incidentalomas with autonomous cortisol secretion (ACS).

METHODS

A total of 149 patients with adrenal incidentalomas were retrospectively evaluated and followed-up for a mean time of 34.6 months at Departments of Endocrinology and Metabolic Diseases Units of four tertiary Spanish hospitals. Patients were grouped as NFAI or ACS adenomas based on two cutoffs in the dexamethasone suppression test (DST): 3.0 µg/dl (NFAI_DST3 or ACS_DST3) and 1.8 µg/dl (ACS_DST1.8 and NFAI_DST1.8).

RESULTS

The mean age of both groups was 62.0 (10.31) and was similar in ACS and NFAI. The prevalence of diabetes, high blood pressure, cardiovascular, and cerebrovascular disease was higher in ACS than in NFAI, but differences only reached statistical significance for cerebrovascular disease using the 3.0 µg/dl cutoff (15.8% vs 2.3%, p = 0.01) and for diabetes using the 1.8 µg/dl cutoff (38.0% vs 22.0%, p = 0.04). No differences were found in the prevalence of dyslipidemia. The prevalence of obesity was lower in patients with ACS than in NFAI 26.3% vs 39.2%, p = 0.18 (NFAI_DST3 vs ACS_DST3) and 32.1% vs 40.6%, p = 0.56 (ACS_DST1.8 vs NFAI_DST1.8), but the differences did not reach statistical significance. Maximum adenoma diameter (R-squared = 0.15, p < 0.001) and cerebrovascular disease (OR = 1.59, p = 0.04) were the only parameters that could be predicted by the DST. The DST was an inadequate predictor of clinical (systolic and diastolic blood pressure, body mass index), hormonal (DHEAS, ACTH, UFC, and basal serum cortisol), biochemical (glucose, cholesterol, LDL, HDL, and triglycerides), and other radiological (laterality, lipid content) parameters. Throughout the follow-up, patients did not develop overt Cushing's Syndrome; three NFAI_DST3 developed ACS_DST3, eight NFAI_DST1.8 developed ACS_DST1.8, and one NFAI_DST1.8 progressed to ACS_DST3. In both groups (NFAI and ACS) the metabolic profile remained stable.

CONCLUSIONS

Our data suggest higher prevalence of diabetes and cerebrovascular disease in ACS patients compared with NFAI. However, probably because of the small sample size, the differences only reached statistical significance using the cutoffs of 1.8 µg/dl for diabetes and 3.0 µg/dl for cerebrovascular disease. Patients with ACS and NFAI rarely progress to more aggressive forms of hypercortisolism, and the metabolic profile usually remains stable during the follow-up.

Autonomous cortisol secretion in adrenal incidentalomas

Adrenal incidentalomas (AI) are one of the most frequent reasons for consultation in Endocrinology, as they are present in 3-10% of the general population. Up to 20% of them may have autonomous cortisol secretion (ACS), a term that refers to AI carriers with biochemical evidence of excess cortisol, but without the "specific" clinical signs of Cushing's syndrome. As ACS is associated with an increased risk of diabetes, obesity, high blood pressure (HBP), osteoporosis, cardiovascular events, and global mortality; its correct identification is of great importance. There are different laboratory assays to detect ACS, but all of them have some limitations. The dexamethasone suppression test is the most accepted for screening. However, there is no consensus on the cutoff point that should be used. Low levels of ACTH and DHEA-S and high urinary free cortisol are also associated with ACS, but in isolation they are of little value to establish the diagnosis. Considering its clinical implications and the lack of consensus in the diagnosis and in which is the most appropriate management of these patients, this review offers a quick reference guide of ACS, presenting an exhaustive review of the topic: its definition, epidemiology, diagnosis, clinical implications, treatment, and follow-up.