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Abstract: TH-PO258

Red Blood Cell Volume Is Not Always Decreased in Anemic CKD Patients

Session Information

Category: Anemia and Iron Metabolism

  • 202 Anemia and Iron Metabolism: Clinical

Authors

  • De Seigneux, Sophie M., University Hospital of geneva, Geneva, Switzerland
  • Ponte, Belen, University Hospital of Geneva, Geneva, Switzerland
  • Martin, Pierre-Yves F., Hospital Universitaire de Geneve, Geneva City, Switzerland
  • Lundby, Carsten, Copenhagen University Hospital, Copenhagen, Denmark
Background

Anemia is defined according to blood hemoglobin concentration ([Hb]), which can be considered a marker of total red blood cell volume (RBCV). However, alterations of plasma volume (PV) may also modify [Hb] without concomitant changes in RBCV. Since anemia and fluid retention are frequent complications of chronic kidney disease (CKD), we hypothesized that anemia during CKD may in part be related to expanded PV without a simultaneous decrease in RBCV.

Methods

To test this hypothesis, we quantified in 50 consecutive stable stage 3-5 CKD outpatients not on dialysis and 7 controls in the same age cathergory: hemoglobin mass, RBCV, PV and total blood volume (BV) using an automated carbon monoxide device. Epo was measured by Elisa. Predicted values for PV, RBCV, and BV were calculated according to nadler's formula for each patient.

Results

CKD patients were divided into anemic and non-anemic patients based on their hemoglobin [Hb] values .
While we demonstrated that RBCV was within the predicted range in anemic patients (+8%, p=0.35) but higher than predicted in non-anemic (+14.5%, p=0.02) patients, both BV and PV were higher than predicted values for non-anemic (+15.5% and +19%, p<0.01) and anemic patients (+ 10.5 and +22%, p<0.01), respectively. Anemic patients had a higher PV than controls ( p<0.01) whereas their RBCV was not different, whereas non anemic CKD patients had higher RBCV than controls ( p<0.01). Thus the cause for anemia in the large majority of the investigated patient population was related mainly to hemodilution and not to a limited erythropoiesis, as also confirmed by the erythropoietin values. [Hb] based anemia over-diagnosed anemia in 20 of the 26 anemic patients.

Conclusion

In conclusion, anemia in CKD as diagnosed by low [Hb] is not necessarily only associated to low RBCV but may also reflect increased plasma volume. This finding could have implications for the treatment of CKD patients and may explain the increased mortality associted to normalization of [Hb] values by rhEpo treatment in the predialysis CKD population.

Funding

  • Government Support - Non-U.S.