Anemia of chronic kidney disease (Proceedings)
Incidence and impact
Anemia is a common abnormality noted in patients with CKD, affecting 32 to 65 per cent of cats with CKD. Treating anemia has many benefits. In people, treatment of anemia improves cognitive function, decreasing depression and increasing quality of life. Treatment of anemia may slow the progression of renal disease in human beings.
Causes of anemia of CKDThe basic mechanisms of anemia include blood loss, red blood cell destructive processes, and failure of bone marrow production.
Blood loss anemia
Blood loss can occur for a variety of reasons in the animal with renal failure, including iatrogenic blood loss anemia from frequent blood sampling for diagnostic testing, gastrointestinal loss, ecto- or endoparasitism, and increased bleeding secondary to uremic platelet function defect.
In human beings with chronic renal failure, gastric ulceration and necrosis are common findings. Clinical experience with animals in renal failure suggests that significant gastrointestinal bleeding occurs in certain individuals. Factors that can contribute to gastrointestinal bleeding in patients with renal failure include increased gastrin levels from decreased renal clearance, concurrent use of non-steroidal anti-inflammatory medications or corticosteroids. Clinical signs of upper gastrointestinal bleeding include hematemesis, melena, or hematochezia. Melena is not always seen in animals with chronic gastrointestinal blood loss since loss can occur in relatively small quantities over time. Other indicators include an elevated BUN/creatinine ratio and microcytic, hypochromic anemia when chronic loss has caused iron deficiency.
The chief hemostatic change that occurs with uremia is impaired platelet function. Total platelet count in animals with renal failure is usually within or slightly below reference range unless the disease etiology causing renal failure also results in thrombocytopenia (e.g. leptospirosis). This thrombocytopathy increases the risk of bleeding.
Red cell destruction
The uremic environment decreases red blood cell survival in some people, but dogs with renal failure had no evidence of increased RBC fragility.