Further evaluation of saline infusion for the diagnosis of primary aldosteronism.

Abstract

Normal subjects, normal-renin hypertensive patients, and low-renin hypertensive patients were evaluated by intravenous saline infusion and with a fludrocortisone acetate (Florinef) protocol to clarify diagnostic criteria for primary aldosteronism that are recommended for the saline infusion protocol. The patients consumed a 200 mEq sodium, 70 mEq potassium diet for 6 days, and on the last 3 days received Florinef 0.5 mg orally twice daily. On Days 3 and 6, urinary aldosterone and tetrahydroaldosterone excretions were determined, and on Days 4 and 7 plasma aldosterone (PA) was determined at 0600 after overnight recumbency and at 0800 after 2 hours of walking. Although the level of normal PA suppression by saline infusion has been commonly defined as 10 ng/dl, a value of 5 ng/dl was originally recommended. In 20 normal subjects and 45 normal-renin hypertensive patients, we found that the PA was almost always suppressed below 5 ng/dl. In 18 of 75 low-renin patients including five with aldosterone-producing adenoma (APA), the PA was never suppressed below 10 ng/dl; thus, these 18 patients had classical primary aldosteronism by generally accepted criteria. The Florinef protocol was performed in eight of these 18 patients and was abnormal in all. An abnormal Florinef protocol was also found in seven of 15 patients studied with PA suppression after saline infusion to between 5 and 10 ng/dl, but in only one of 24 patients studied with PA suppression below 5 ng/dl. Additional studies in the subgroup with abnormal results from the Florinef protocol indicated that none of these patients had evidence of APA, so they had nontumorous primary aldosteronism (NTPA).(ABSTRACT TRUNCATED AT 250 WORDS)

Confirmatory testing in normokalaemic primary aldosteronism: the value of the saline infusion test and urinary aldosterone metabolites

“…Previous studies have employed mainly the saline infusion test to separate Conn's adenoma from essential hypertension (18,19,21) and were performed in hypokalaemic patients. Another study in hypokalaemic aldosteronism investigated the value of the test in differentiating both adenoma and hyperplasia from essential hypertension (34), showing a sensitivity of 96% and a specificity of 84%, which is comparable to our findings in hypokalaemic patients. In contrast, the low sensitivity of this test was recently demonstrated by Stowasser et al (3), who reported a sensitivity of 18-30% in a group of mainly normokalaemic patients with primary aldosteronism.…”

Prevalence of Primary Aldosteronism among Unselected Hypertensive Patients: A Prospective Study Based on the Use of an Aldosterone/Renin Ratio above 25 as a Screening Test

“…In the present study we chose the intravenous saline loading test, which has the advantages of low cost, ease and practicability for both the patients and the clinicians, requiring only a brief outpatient visit (8,10,12). The level of normal ALD suppression by saline infusion has been commonly defined as 10 ng/ml (12,16,21), but a cut-off value of 5 ng/ ml has also been recommended (8,10,35). To minimize the possibility of misdiagnosing PA as essential hypertension, in agreement with other authors (18) we employed the cut-off value of a post-saline ALD level of 7.5 ng/dl with saline loading.…”

“…The confirmatory test was an i.v. saline load (2 l of 0.9% NaCl infused over 4 h with the patient supine) (8,10,12). The test was considered positive if the post-test ALD levels were greater than 7.5 ng/dl (18).…”

“…The ARR has been advocated as a convenient and effective method to screen for PA, with some limitations concerning a possible reduction of its accuracy by various antihypertensive drugs, posture changes, time of day, potassium levels and renal insufficiency (7)(8)(9). An elevated ARR is not diagnostic by itself and PA must be confirmed by other tests, such as a saline infusion test, fludrocortisone suppression test, captopril test and oral salt loading test, which are able to demonstrate an inappropriate autonomous ALD production (8,(10)(11)(12)(13)(14). The application of the ARR to a broader population of hypertensives has uncovered a higher prevalence of PA in both hypertensive clinic and primary care populations, with prevalence rates ranging from 3% to 32% and most patients being normokalemic (15)(16)(17)(18)(19)(20)(21).…”

Ventricular repolarization before and after treatment in patients with secondary hypertension due to renal-artery stenosis and primary aldosteronism

“…QT intervals were corrected for the previous cardiac cycle length according to Hodges' formula: QTcH (ms)¼QT+1.75 (heart rateÀ60). 15 QTcH was considered prolonged when 4440 ms, in accordance with the criteria commonly used in the literature.…”