Israel Medical Association Journal

Background: Patients with rheumatic diseases, such as rheumatoid arthritis (RA) and ankylosing spondylitis (AS), encounter significantly higher rates of cardiovascular morbidity and mortality. The renin-angiotensin-aldosterone system maintains hemodynamic stability through blood pressure regulation. When dysregulated, this system has been implicated in various pathological conditions, including cardiovascular events.

Objectives: To investigate the levels of renin and aldosterone in RA and AS patients.

Methods: Three groups were recruited: patients with RA, patients with AS, and healthy controls. Subjects were excluded if they had a diagnosis of hypertension, hyperaldosteronism, or renal artery stenosis, or were taking drugs that might have affected renin levels. Renin and aldosterone levels were measured using commercially available kits. Data were analyzed using univariate analyses and multivariate regression analyses.

Results: Fifty-one subjects were enrolled in the study: 15 with RA, 4 with AS, and 32 healthy controls. At the univariate analysis, the three groups differed in age (P = 0.005), renin levels (P = 0.013), and aldosterone-to-renin ratio (P = 0.019). At the post-hoc tests, both AS and RA patients differed from controls for renin levels and the aldosterone-to-renin ratio. At the multivariate regression analysis, AS patients had lower renin values than controls (beta standardized regression coefficient -0.323, P = 0.022).

Conclusion: Patients with RA tended to have lower levels of plasma renin compared to healthy subjects. This finding indicates that the renin-angiotensin-aldosterone system might not be directly involved in the process that results in increased cardiovascular events in rheumatoid arthritis.

Background: Anti-glomerular basement membrane (GBM) antibody disease, or Goodpasture’s disease, is the clinical manifestation of the production of anti-GBM antibodies, which causes rapidly progressive glomerulonephritis with or without pulmonary hemorrhage. Anti-GBM antibody detection is mandatory for the diagnosis of Goodpasture’s disease either from the serum or kidney biopsy. Renal biopsy is necessary for disease confirmation; however, in cases in which renal biopsy is not possible or is delayed, serum detection of anti-GBM antibody is the only way for diagnosis.

Objectives: To assess the predictive value of positive anti-GBM antibodies in a clinical setting. 

Methods: Data from anti-GBM antibody tests performed at one medical center between 2006 and 2016 were systematically and retrospectively retrieved. We recruited 1914 patients for the study. Continuous variables were computed as mean ± standard deviation, while categorical variables were recorded as percentages where appropriate. Sensitivity and specificity of anti-GBM titers were calculated. Kaplan–Meyer analysis was performed, stratifying survival according to the anti-GBM antibody titers.

Results: Of the 1914 anti-GBM test results detected, 42 were positive, 23 were borderline, 142 were excluded, and 1707 results were negative. Male-to-female ratio was 1:1.2. Sensitivity of anti-GBM test was 41.2% while specificity was 85.4%. Concerning the Kaplan–Meyer analysis, overall survival was 1163.36 ± 180.32 days (median 1058 days). 

Conclusions: Our study highlights the lack of sensitivity of serological testing of anti-GBM titers. Comparing survival curves, the survival correlated with anti-GBM titer only in a borderline way. Because highly sensitive bioassays are not routinely used in clinics, renal biopsy is still pivotal for Goodpasture’s disease diagnosis.