Investigating the cut-off values of captopril challenge test for primary aldosteronism using the novel chemiluminescent enzyme immunoassay method: a retrospective cohort study

The measurement evolution enabled more accurate evaluation of aldosterone production in hypertensive patients. However, the cut-off values for novel assays have been not sufficiently validated. The present study was undertaken to validate the novel chemiluminescent enzyme immunoassay for aldosterone in conjunction with other methods. Moreover, we also aimed to establish a new cut-off value for primary aldosteronism in the captopril challenge test using the novel assay. First, we collected 390 plasma samples, in which aldosterone levels measured using liquid chromatography-mass spectrometry ranged between 0.18 and 1346 ng/dL. The novel chemiluminescent enzyme immunoassay showed identical correlation of plasma aldosterone with liquid chromatography-mass spectrometry, in contrast to conventional radioimmunoassay. Further, we enrolled 299 and 39 patients with primary aldosteronism and essential hypertension, respectively. Plasma aldosterone concentrations measured using the novel assay were lower than those measured by radioimmunoassay, which resulted in decreased aldosterone-to-renin ratios. Subsequently, positive results of the captopril challenge test based on radioimmunoassay turned into "negative" based on the novel assay in 45% patients with primary aldosteronism, using the conventional cut-off value (aldosterone-to-renin activity ratio > 20 ng/dL per ng/mL/h). Receiver operating characteristic curve analysis demonstrated that aldosterone-to-renin activity ratios > 8.2 ng/dL per ng/mL/h in the novel assay was compatible with the conventional diagnosis (sensitivity, 0.874; specificity, 0.980). Our study indicates the great measurement accuracy of the novel chemiluminescent enzyme immunoassay for aldosterone, and the importance of measurement-adjusted cut-offs in the diagnosis of primary aldosteronism.

The role of confirmatory tests in the diagnosis of primary aldosteronism

Confirmatory tests for diagnosis of primary aldosteronism (PA) play an important role in sparing patients with a false-positive aldosterone-to-renin ratio (ARR) screening test from undergoing invasive subtyping procedures. We recommend that patients with a positive ARR test should undergo at least one confirmatory test to confirm or exclude the diagnosis of PA before directly proceeding to subtype studies, except for patients with significant PA phenotypes, including spontaneous hypokalemia, plasma aldosterone concentration >20 ng/dL plus plasma renin activity below a detectable level. Although a gold standard confirmatory test has not been identified, we recommend that saline infusion test and captopril challenge test, which were widely used in Taiwan. Patients with PA have been reported to have a higher prevalence of concurrent autonomous cortisol secretion (ACS). ACS is a biochemical condition of mild cortisol overproduction from adrenal lesions, but without the typical clinical features of overt Cushing's syndrome. Concurrent ACS may result in incorrect interpretation of adrenal venous sampling (AVS) and may lead to adrenal insufficiency after adrenalectomy. We recommend screening for ACS in patients with PA scheduled for AVS examinations as well as for adrenalectomy. We recommend the 1-mg overnight dexamethasone suppression test as screening method to detect ACS.

Computed tomography combined with confirmatory tests for the diagnosis of aldosterone-producing adenoma

Primary aldosteronism (PA) is the most common cause of secondary hypertension, and a simpler non-invasive method for identification of aldosterone-producing adenoma (APA) is required to improve the standard of medical treatment for PA patients. We retrospectively analyzed the clinical data of hypertensive patients with an aldosterone/renin ratio (ARR) ≥30 (ng/dL)/(ng/mL/h), and surgical and/or adrenal venous sampling (AVS) results served as the gold standard for APA diagnosis. The study aimed to determine whether positive CCT and SIT results plus a unilateral adrenal nodule found by CT allow unambiguous identification of an APA with high diagnostic specificity. Clinical data from 71 APA and 47 non-APA patients were collected, and logistic regression analysis was performed to construct models. Receiver operating characteristic (ROC) curves were used to analyze the efficacy of diagnostic tests. The areas under the ROC curves (AUCs) were similar between the post-SIT plasma aldosterone concentration (PAC) and post-CCT PAC (p > 0.05). The optimal post-SIT and post-CCT PAC cutoff values were 17.2 and 21.2 ng/dL, respectively. Positive CT findings combined with a post-SIT PAC >17.2 ng/dL or post-CCT PAC >21.2 ng/dL provided specificities of 97.8% and 95.7% for predicting APA, respectively. Logistic diagnostic models 1 (M1, CT finding + post-SIT PAC) and 2 (M2, CT finding + post-CCT PAC) were built, which showed equivalent diagnostic value (AUC = 0.959 and 0.932, respectively) (p > 0.05). The models combining CT findings with post-SIT PACs or post-CCT PACs represent an easier method to distinguish APA patients from other hypertensive patients with positive upright ARR results, especially in primary care where AVS may be unavailable.

Prediction of unilateral hyperaldosteronism on adrenal vein sampling using captopril challenge test in patients with primary aldosteronism

Captopril challenge test (CCT) is a simple and safe confirmatory test for primary aldosteronism (PA). We investigated the effectiveness of the indices after captopril administration for prediction of unilateral hyperaldosteronism (UHA) on adrenal vein sampling (AVS). We studied 238 patients with PA who had CCT and successful AVS between July 2007 and December 2019 in Sapporo City General Hospital. Receiver operating characteristic (ROC) curve analysis showed that the diagnostic performance for prediction of UHA on AVS in regard to the reduction rate of plasma aldosterone concentration (PAC) after captopril administration was inferior to aldosterone to renin ratio (ARR) and PAC (area under the ROC curve 0.72 vs. 0.84, 0.72 vs. 0.89, respectively, both p < 0.01). Based on the optimal cut-off values in ARR (897 pg/mL/ng/mL/h, sensitivity 64.6%, specificity 93.0%) and PAC (203 pg/mL, sensitivity 73.9%, specificity 93.0%) after captopril administration, the patients were divided into three groups: (1) both positive, (2) one positive, and (3) both negative. The prevalence of UHA on AVS in the three groups were 90.0%, 52.9%, and 7.3%, respectively. In the first group, 31 of 32 patients with unilateral nodular lesion on CT had an ipsilateral unilateral AVS. In conclusion, the combination of post-captopril ARR and PAC is useful for prediction of laterality diagnosis on AVS. AVS is strongly recommended in patients with both positive or one positive results for the optimal cut-off values of post-captopril ARR and PAC and is weakly recommended in patients with both negative results.

[The Diagnostic Value of Captopril Challenge Test for Primary Aldosteronism]

OBJECTIVE

To investigate the diagnostic value of different captopril challenge test (CCT) diagnostic criteria for diagnosing primary aldosteronism (PA).

METHODS

We collected the clinical data of 184 patients with hypertension retrospectively in West China Hospital of Sichuan University. Receiver operating characteristic (ROC) curves were used to analyze the post-CCT efficacy of aldosterone renin activity ratio (ARR), plasma aldosterone concentration (PAC), plasma renin activity (PRA) and PAC suppression rate for PA diagnosis.

RESULTS

This study included 125 cases of primary aldehyde (PA group) and 59 cases of essential hypertension (EH group), and there were 38 normal renin primary hypertension (NREH group) and 21 low renin primary hypertension (LREH group) in EH group. The post-CCT PAC suppression rate (median (P 25, P 75)) of EH and PA group were 0.190 (0.083, 0.351) and 0.125 (0.024, 0.237), respectively. Compared with the NREH group, the basic and post-CCT PRA of LREH group were lower ( P<0.001), and there were no significant differences compared with the PA group ( P>0.05). We found significant overlap of post-CCT PRA and ARR between PA group and LREH group, while the overlap of post-CCT PAC between the two groups was small. In differential diagnosis of PA and EH, the areas under ROC curve of the post-CCT ARR, PAC, PRA and PAC suppression rate were 0.860 (95% confidence interval ( CI): 0.800-0.907), 0.881 (95% CI: 0.825-0.924), 0.771 (95% CI: 0.703-0.831) and 0.632 (95% CI: 0.558-0.701), respectively. There was no significant difference between the first two indexes ( Z=0.443, P=0.658), and both of them were higher than the latter two ( P<0.05). The optimal post-CCT cut-off values for ARR and PAC in differential diagnosis of PA and EH were 19.24 ng·dL -1 with a sensitivity of 78.4% and a specificity of 88.1%, and 32.47 (ng·dL -1)/(ng·mL -1·h -1) with a sensitivity of 84.17% and a specificity of 72.41%.

CONCLUSION

Both ARR and PAC have higher diagnostic value than the post-CCT PAC suppression rate, post-CCT PAC is especially suitable as a confirmatory testing criterion of PA.

Parameters of captopril challenge test can predict results of other confirmatory tests for primary aldosteronism and propose the next test to be done

In Japan, primary aldosteronism (PA) is diagnosed if any one of the captopril challenge test (CCT), saline infusion test (SIT), furosemide-upright test (FUP), and oral salt-loading test (OST) is positive. The present study aimed to investigate if parameters of CCT, the safest confirmatory test, could predict decisions of other tests and propose the next test to diagnose PA in CCT-negative patients. In a cross-sectional design, 142 patients, who were referred to our hospital for the scrutiny of PA and underwent at least two confirmatory tests, were enrolled. While 123 patients underwent all of the CCT, SIT, and FUP, the OST was successfully done in only six patients and excluded from further analyses. CCT parameters showing correlations of higher degrees with SIT and FUP parameters were selected, and their powers to predict SIT and FUP decisions were investigated by receiver operating characteristic analyses. Proposals of the next test based on the CCT parameters were validated with SIT and FUP decisions in subsets of CCT-negative patients divided by cut-offs of the CCT parameters. The plasma aldosterone concentration and plasma renin activity 60 min after the load of CCT (CCT60-PAC and CCT60-PRA) were selected, and CCT60-PAC ≤59.0 pg/mL and CCT60-PRA ≥1.05 ng/mL/h could predict negativities of SIT and FUP, respectively, with >95% specificities. Based on the validation, the present study suggested the SIT as the next test to be done if the CCT-negative patient belonged to the subset with CCT60-PAC >59.0 pg/mL and CCT60-PRA ≥1.05 ng/mL/h, otherwise the FUP should be selected.

The characteristics of captopril challenge test-positive patients using various criteria

Introduction:

The captopril challenge test (CCT) is the major confirmatory test for primary aldosteronism (PA), and frequently carried out because of its convenience. However, it presents false-negative results with a certain probability, and as there are many criteria for CCT, it is not concluded yet which criteria to use.

Materials and methods:

A total of 71 PA patients were evaluated. We compared CCT-positive and CCT-negative patients in the following three criteria: plasma aldosterone/renin ratio (ARR) >200 after the CCT (criterion 1); plasma aldosterone concentration (PAC) >120 pg/ml after the CCT (criterion 2); and PAC suppression <30% of PAC before CCT (criterion 3).

Results:

The positive rate was 70.4%, 64.8% and 54.9% for criterion 1, criterion 2 and criterion 3, respectively. With criterion 1, the baseline plasma renin activity was lower, thus baseline ARR was higher in CCT-positive patients. With criterion 2, PAC was higher and estimated sodium intake and K were lower in CCT-positive patients. With criterion 3, K and PAC were lower in CCT-positive patients. Although it was not significant, in the patients with high sodium intake, the positive rate of criterion 1 was higher than that of the other criteria.

Conclusions:

ARR>200 is the valuable criterion for the diagnosis of PA.

The captopril challenge test for diagnosing primary Aldosteronism in a Chinese population

BACKGROUND

The Captopril challenge test (CCT) is an easy-conduct confirmatory test for diagnosing primary aldosteronism (PA). Guidelines show that plasma aldosterone is normally suppressed by captopril (> 30%) in primary hypertension (PH) and in healthy people. It is unclear whether this standard is applicable in Chinese subjects. The aim of the present study was to investigate the post-CCT efficacy of plasma aldosterone concentration (PAC) suppression and determine the post-CCT aldosterone renin activity ratio (ARR) and PAC for PA diagnosis.

METHODS

We recruited 110 consecutive patients with PA, 163 with primary hypertension (PH), and 40 healthy volunteers (NC). The CCT was conducted in all patients. Total sodium intake was estimated from 24-h urinary excretions. ROC curves were used to analyze the efficiency of different CCT diagnostic criteria for diagnosing PA.

RESULTS

In NC and PH patients, PRA was increased and PAC was decreased post-CCT (P < 0.05). The mean degree of PAC decline after CCT was approximately 9.3%, and only 11.7% of the patients with PH showed a greater than 30% suppression of PAC after CCT. In patients with PA, the post-CCT change in PRA and PRC was slight. The post-CCT degree of PAC decline was unrelated to dietary salt intake. The areas under the ROC for the post-CCT ARR, PAC and PAC suppression % were 0.994, 0.754 and 0.606, respectively. The optimal post-CCT cutoff value for ARR for diagnosing PA was 20, which yielded a sensitivity and specificity of 94.0 and 99.4%, respectively.

CONCLUSIONS

The PAC suppression percentage after CCT recommended by current clinical guidelines is not applicable when diagnosing Chinese subjects with PA. Compared to post-CCT PAC, post-CCT ARR was a better approach, having an optimal cutoff of 20 when interpreting the results of the CCT in Chinese patients. We found no relationship between high salt intake and low responses of the renin-angiotensin system (RAS) to the CCT.

[The application of captopril challenge test in the diagnosis of primary aldosteronism]

Objective: To evaluate the value of captopril challenge test (CCT) in the diagnosis of primary aldosteronism (PA). Methods: A total of 674 patients [(45.0±13.7) years, men 341, women 333] admitted to Peking Union Medical College Hospital from 2000 to 2015 were analyzed. Among them, 222 subjects were with essential hypertension (EH), 28 were with pheochromocytoma (PHEO), 246 were with idiopathic hyperaldosteronism (IHA) and 178 were with aldosterone producing adenoma (APA). All patients received CCT. 24 h urine sodium was measured in partial patients. Plasma renin activity (PRA), aldosterone (ALD) were detected. Results: Compared with EH [PRA: before 0.5(0.2, 0.9) μg·L(-1)·h(-1,) after 0.8(0.4, 1.5) μg·L(-1)·h(-1;) ALD: before (393±122) pmol/L, after (360±97) pmol/L] and PHEO [PRA: before 0.3(0.1, 0.9) μg·L(-1)·h(-1,) after 0.4(0.1, 1.6) μg·L(-1)·h(-1;) ALD: before (396±108) pmol/L, after (374±114) pmol/L], lower levels of PRA and higher levels of ALD before and after CCT were observed in PA patients [PRA: before 0.1 (0.1, 0.2) μg·L(-1)·h(-1,) after 0.1 (0.1, 0.2) μg·L(-1)·h(-1;) ALD: before (468±216) pmol/L; after (457±199) pmol/L]. After CCT, the suppression rate of ALD [2.8% (-8.8%, 15.4%) vs 6.6% (-4.3%, 17.6%)] and increasing rate of PRA [0(0, 50%) vs 50%(0, 200%)] in PA patients were lower than those in EH patients. The ALD/PRA ratio (ARR) were higher in PA than that in EH or PHEO patients. In the EH subjects, ALD levels of seated posture were higher than those of recumbent posture both before and after receiving captopril, but with no changes in ARR after CCT. No significant differences in ALD and ARR (before and after receiving captopril) were observed between seated and recumbent position in the PA group. The ARR after CCT tended to decrease in EH subjects with elevated urine-sodium compared with those with normal urine-sodium. No changes could be viewed in ALD and PRA levels between normal urine-sodium and elevated urine-sodium groups among APA, IHA and EH patients either before or after CCT. Among patients with APA, the ALD levels before CCT and the ARR after CCT were lower in the patients with AngiotensionⅡ(AngⅡ) reactive than those without. A ROC curve analysis suggested that the optimal cutoff value was 46.2 (ALD unit: ng/dl; PRA unit: μg·L(-1)·h(-1)) for ARR after challenge in diagnosing PA, with the sensitivity of 88.7% and specificity of 84.8%. Conclusions: ARR after 25 mg captopril had high sensitivity and specificity in diagnosis of PA with the cutoff of 46.2. Seated CCT could replace recumbent CCT as a more confirmatory test. The PRA increasing rate should be taken into consideration when diagnosis of PA.

Saline Infusion Test highly associated with the incidence of cardio- and cerebrovascular events in primary aldosteronism

Primary aldosteronism (PA) is caused by excess secretion of aldosterone and is an independent risk factor for cardio-cerebro-vascular (CCV) events. The goal of treatment of PA should include prevention of CCV events. A definitive diagnosis of PA is established by confirmatory tests [saline infusion test (SIT), furosemide upright test (FUT) and captopril challenge test (CCT)]. However, there is no information on whether the hormone levels measured by these confirmatory tests are associated with CCV events. The aim of this retrospective study was to elucidate the relationship between the results of the above confirmatory tests and prevalence of CCV disease in patients with PA. The study subjects were 292 PA patients who were assessed for past history of CCV events at the time of diagnosis of PA. CCV events were significantly higher in patients with positive than negative SIT (12.8% vs. 3.3%, p=0.04). There were no differences in the incidences of CCV events between patients with positive and negative CCT and FUT (CCT: 11.0% vs. 3.9%, p=0.13, FUT: 6.1% vs. 5.7%, p=0.93). Our results demonstrated a higher incidence of CCV disease in PA SIT-positive patients compared to those with negative test. SIT is a potentially useful test not only for the diagnosis of PA but also assessment of the risk of CCV events.

Diagnostic Role of Captopril Challenge Test in Korean Subjects with High Aldosterone-to-Renin Ratios

BACKGROUND

Diagnosis of primary aldosteronism (PA) begins with aldosterone-to-renin ratio (ARR) measurement followed by confirmative tests. However, the ARR has high false positive rates which led to unnecessary confirmatory tests. Captopril challenge test (CCT) has been used as one of confirmatory tests, but the accuracy of it in the diagnosis of PA is still controversial. We aimed to examine the clinical efficacy of CCT as a post-screening test in PA.

METHODS

In a prospective study, we enrolled subjects with suspected PA who had hypertension and ARR >20 (ng/dL)/(ng/mL/hr). Sixty-four patients who underwent both the saline infusion test and the CCT were included.

RESULTS

The diagnostic performance of plasma aldosterone concentration (PAC) post-CCT was greater than that of ARR post-CCT and ARR pre-CCT in PA (area under the curve=0.956, 0.797, and 0.748, respectively; P=0.001). A cut-off value of 13 ng/dL showed the highest diagnostic odds ratio considering PAC post-CCT at 60 and 90 minutes. A PAC post-CCT of 19 ng/dL had a specificity of 100%, which can be used as a cut-off value for the confirmative test. Determining the diagnostic performance of PAC post-CCT at 90 minutes was sufficient for PA diagnosis. Subjects with PAC post-CCT at 90 minutes <13 ng/dL are less likely to have PA, and those with PAC post-CCT at 90 minutes ≥13 but <19 ng/dL should undergo secondary confirmatory tests.

CONCLUSION

The CCT test may be a reliable post-screening test to avoid the hospitalization in the setting of falsely elevated ARR screening tests.