Evaluating the diagnostic capacity of the saline infusion and captopril challengetests for primary aldosteronism

Isabella Mantellini Gonzalez; Sime Rogic Valencia; Ines Borrego Soriano; Paula Vazquez Perez; Rosa Maria Garcia Moreno; Arturo Lisbona Catalan; Gumersindo Fernandez Vazquez; Oscar Moreno Dominguez; Beatriz Barquiel Alcala; Miriam Zapatero Larrauri; Maria Luisa Gonzalez Casaus; Irene Aguilera Garcia; Alexa Pamela Benitez Valderrama; Ines Lobo; Cristina Alvarez Escola; Patricia Martin Rojas-Marcos; Paola Parra Ramirez

doi:10.1530/endoabs.90.EP13

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Endocrine Abstracts (2023) 90 EP13 | DOI: 10.1530/endoabs.90.EP13

ECE2023 Eposter Presentations Adrenal and Cardiovascular Endocrinology (124 abstracts)

Evaluating the diagnostic capacity of the saline infusion and captopril challengetests for primary aldosteronism

Isabella Mantellini Gonzalez ¹ , Sime Rogic Valencia ¹ , Inés Borrego Soriano ¹ , Paula Vázquez Pérez ¹ , Rosa María García Moreno ¹ , Arturo Lisbona Catalán ¹ , Gumersindo Fernández Vázquez ¹ , Oscar Moreno Domínguez ¹ , Beatriz Barquiel Alcala ¹ , Miriam Zapatero Larrauri ¹ , María Luisa González Casaus ² , Irene Aguilera García ¹ , Alexa Pamela Benítez Valderrama ¹ , Ines Lobo ¹ , Cristina Álvarez Escolá ¹ , Patricia Martin Rojas-Marcos ¹ & Paola Parra Ramírez ¹

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Author affiliations

¹Hospital Universitario La Paz, Endocrinología y Nutrición., Madrid, Spain; ²Hospital Universitario La Paz, Análisis Clínicos, Madrid, Spain

Introduction: Primary aldosteronism (PA) is the most common cause of secondary hypertension. Guidelines recommend a confirmatory test in the majority of suspected cases: oral sodium loading, saline infusion test (SIT), captopril challenge test (CCT), or fludrocortisone suppression test. The SIT and CCT are most commonly used in clinical practice to study autonomous aldosterone secretion.

Objectives and Methods: We compared the CCT’s diagnosis performance to that of the SIT. A retrospective study of PA confirmatory tests was conducted at Hospital Universitario La Paz (Madrid, Spain). Tests performed between 2019 and 2022 were included. All cases underwent confirmatory tests (CCT or SIT) according to the clinician’s preference or the patient’s characteristics and comorbidities. Antihypertensive medications were changed or discontinued for the confirmatory test following the guidelines. Dietary sodium intake was unrestricted. For CCT, patients received 50-mg captopril orally at 9 AM. The SIT involved the infusion of 2L of 0.9% saline IV over 4 hours. Both tests were performed in a seated position. The results of the different tests were compared.

Results: 60 confirmatory tests were performed: 27 CCT and 33 SIT (Table 1). In comparison to CCT, the SIT got more indeterminate results (7.4% vs 39.4%, P 0.014). Age, gender, history of hypertension or hypokalemia, renin and aldosterone determinations (screening and during tests), urine aldosterone (if studied), presence of an adrenal nodule, or 1mg dexamethasone suppression test (if studied) did not differ between groups. Some patients with indeterminate results underwent a second confirmatory test. CCT was performed on 6 patients with non-conclusive SIT, with 5 definite results (2 positives and 3 negatives) and 1 indeterminate. On the other hand, the only patient who had an indeterminate CCT and underwent a SIT, also obtained an inconclusive result.

Table 1
	Captopril Challenge Test (n=27)	Saline Infusion Test (n=33)
Indeterminate result	2	13
Positive result	14	13
Negative result	11	7

Conclusion: In diagnosing or ruling out PA, the CCT (50 mg) was more accurate than SIT. For the vast majority of patients with an indeterminate SIT, the CCT yielded a conclusive result.