#1816 CA 125 as a surrogate marker for plasma volume in patients with cardiorenal syndrome
Authors: Silva André , Pepe Bruno , Pimenta Gonçalo , Matias Patrícia , Branco Patrícia , Calça Ana Rita 
Published: May 2024

Abstract

Background and Aims
Assessing volume status in heart failure (HF) and end-stage chronic kidney disease (CKD) is challenging. Plasma volume expansion is an early step in the pathophysiology of decompensated HF and an independent risk factor for death and HF hospitalization, and should be addressed early. Evaluating plasma volume, especially its variation with diuretic therapy, can be a useful clinical tool for guiding decongestive therapy. There's a growing need for accurate and simple tools to guide clinician decisions on patient volume management.
Cancer antigen 125 (CA125), a glycoprotein produced in mesothelial cells in the pericardium, pleura, or peritoneum, is primarily associated with ovarian and gynecological malignancies. Recent studies link CA125 to inflammation and congestion. In acute HF, elevated CA125 is associated with fluid overload indicators like increased central venous and pulmonary wedge pressure. Elevated CA125 in acute HF patients is linked to worse outcomes in death and hospital stay length. Evidence supports CA125-guided therapy in acute HF, but its role in managing chronic volume overload is still uncertain.
We aim to assess the relationship between CA125 levels and estimated plasma volume (ePV).

Method
A retrospective unicentric observational study was conducted between June 2022, and April 17, 2023, at the Renocardiac clinic of a tertiary hospital. Clinical data were extracted from electronic patient records. CKD staging was determined following the Kidney Disease Improving Global Outcomes (KDIGO) classification. ePV was calculated using the Kaplan-Hakim formula. CA125 and ePV were assessed for the same patient in 2 different visits and their variation was calculated. The correlation between CA125 and ePV, as well as CA125 and ePV variation, was evaluated using Spearman's rank correlation coefficient for bivariate analysis, conducted with IBM SPSS®.

Results
This study comprised 65 patients, totaling 124 hospital visits. The patient demographic was 67.7% male, with a mean age of 76.4 (±12.47) years. In terms of CKD staging, 48.5% were classified as KDIGO 5, 40.6% as KDIGO 4, 9.4% as KDIGO 3, and 1.5% as KDIGO 2.
HF etiology distribution included 59% ischemic, 9.8% hypertensive, 6.5% valvular, and 24.5% other causes. The mean ejection fraction was 37.35 (±12.36)% and 19% had preserved ejection fraction; 75% of them were treated with prognostic-modifying medication, including SGLT2 inhibitors. This proportion was lower (19%) in patients with reduced ejection fraction, receiving ACE/angiotensin ± neprilysin inhibitor + mineralocorticoid receptor inhibitor + beta-blocker + SGLT2 inhibitor. During the follow-up period, 13 hospitalizations, 1 major adverse cardiovascular event (MACE), and 5 deaths were recorded.
The mean CA125 level was 193.98 (±154.55) U/mL, and patients had a mean ePV of 2.41 (±1.19) L. A significant positive correlation was found between CA125 levels and ePV (r = 0.355, p = 0.000). However, there was no significant correlation between the variation of CA125 and ePV levels between visits (p = 0.535).

Conclusion
This study focuses on a population with limited implementation of disease-modifying therapy due to advanced CKD, complicating the clinical management of volume status, kidney function, potassium levels, and long-term prognosis in both CKD and HF.
CA125 shows potential clinical utility as a marker of congestion, aiding clinicians in assessing volume status by correlating with plasma volume. However, this study found no correlation between CA125 variation and changes in plasma volume. The outpatient nature of the studied population, typically euvolemic, may hinder assessing the relationship between CA125 and ePV changes. Future studies with larger sample sizes are essential to clarify this relationship and potentially identify volume-expanded patients early.