Discussion
Our data show that fluid status, defined as the OH level, is one of the major determinants of low hemoglobin concentrations in patients with stage 3 to 5 CKD.
Anemia in these patients was not only independently related to their impaired renal function, but also to an increased fluid status.
Furthermore, anemia with excess OH was associated with more traditional and nontraditional cardiovascular risk
Anemia is common among patients with CKD and is known to impair their prognosis. In our study population of CKD stage 3 to 5, the prevalence of anemia was 68%, which is compatible with previously published data showing that 50% to 60% of patients with stage 4 CKD are anemic,
and the prevalence of anemia increases to 75% to 92% in patients reaching stage 5 CKD.
14,15 Absolute or relative erythropoietin deficiency is involved in the pathophysiology of CKD-associated anemia. Although treatment with ESAs markedly improved patient-perceived quality of life and reduced the need for blood transfusions,16 the results from the Correction of Hemoglobin and Outcomes in Renal Insufficiency (CHOIR), Cardiovascular risk Reduction by Early Anemia Treatment with Epoetin b (CREATE), and TREAT trials all demonstrated an increased risk of CKD progression or cardiovascular events such as stroke, thrombosis, or death at nearly normal hemoglobin concentrations and higher ESA doses in patients with ND-CKD.
2–4 However, the many confounding factors that accompany CKD may have prevented clinicians from discerning the specific role anemia plays in the poor outcomes.
Fluid retention is a major component of the clinical syndrome of moderate-to-advanced CKD.
Patients with CKD have similarities to those with heart failure in that both populations frequently retain fluid and have excessively high cardiovascular mortality.