Renin–Angiotensin–Aldosterone Axis Activity in Women with Chronic Endometritis: A Prospective Observational Study

Chronic endometritis (CE) is a persistent inflammatory disorder of the endometrium that is histopathologically characterized by CD138-positive plasma cells within the endometrial stroma. This study evaluated components of the renin–angiotensin–aldosterone system (RAAS) and interleukin-6 (IL-6) in infertile women with CE. Thirty-nine infertile women undergoing diagnostic hysteroscopy with endometrial biopsy were included. A total of 21 women were classified as CE-positive and 18 as CE-negative. Fasting blood samples were collected 48 h before hysteroscopy (t1) and approximately 2.5 h before the procedure (t2) to assess plasma renin, serum aldosterone, the aldosterone-to-renin ratio (ARR), sodium, potassium, progesterone, thyroid-stimulating hormone (TSH), and IL-6. Exploratory analyses were performed according to the extent of CD138-positive plasma-cell infiltration (plasma-cell burden, stratified as <20 or ≥20 cells/high-power field) and persistence versus resolution of CE after antibiotic treatment. Baseline characteristics, including body mass index (BMI), infertility duration, and anti-Müllerian hormone (AMH), were comparable between groups. No significant differences in the parameters were observed between CE-positive and CE-negative women. No consistent RAAS or inflammatory differences emerged according to plasma-cell burden or CE persistence after treatment. These findings suggest that CE is not associated with measurable systemic RAAS activation or IL-6 changes, supporting the hypothesis of local CE alterations.