Iron deficiency in patients with chronic thromboembolic pulmonary hypertension: prevalence, pathogenesis, and diagnostic criteria

Aim . To assess the prevalence of iron deficiency in patients with chronic thromboembolic pulmonary hypertension (CTEPH), their impact on survival and functional status, and to identify the most informative indicator for assessing iron deficiency (ID) in this group. Material and methods . The study included 283 patients with a newly diagnosed CTEPH (mean age 56,0 [44,0; 67,0] years, 47% men). All patients underwent iron metabolism (serum iron, transferrin, serum ferritin, soluble transferrin receptors), proinflammatory cytokine (interleukin (IL)-6, -8, -10 and monocyte chemotactic protein (MCP-1)), hepcidin, and endothelin-1 tests. The control group consisted of 24 healthy donors (mean age, 58 [39; 64] years; men, 46%). Results . The prevalence of anemia was 17% (n=48), and the proportion of patients with iron deficiency anemia was 78% (n=37). No differences were found in pulmonary circulation hemodynamics or functional status when comparing patients with and without anemia, nor was there an effect of anemia on three-year patient survival. An increase in the level of C-reactive protein, IL-10 and MCP-1 in patients with CTEPH and their association with iron metabolism parameters were demonstrated. Depending on the criteria used, the prevalence of ID ranged from 24,5% to 69,1%. For the transferrin saturation, a weak direct correlation was established with such prognostic indicators as the 6-minute walk test (r=0,21; p=0,032), peak oxygen consumption (r=0,26; p=0,044) and mixed venous oxygen saturation (r=0,34; p=0,040). In addition, significant differences in the severity of CTEPH were revealed when dividing into groups according to transferrin saturation value of more/less than 20%. Three-year survival analysis in patients with CTEPH revealed significant differences in survival rates for ID criteria based on soluble transferrin receptor levels (>4,4 for men; >5,0 for women (Roche Diagnostics)) and our proposed ID criteria (serum ferritin (SF)