Final answer:
In stage 5 CKD, the lifespan of RBCs is significantly reduced to about 30 days, which contributes to the common complication of anemia in these patients due to both increased hemolysis and decreased RBC production.
Step-by-step explanation:
In patients with stage 5 chronic kidney disease (CKD), the life span of red blood cells (RBCs) is significantly reduced, often lasting less than half of the normal span, decreasing to approximately 30 days.
In healthy individuals, RBCs have a life span of approximately 120 days, mainly determined by the durability of the cell membrane as it traverses narrow capillaries, particularly in the spleen. However, in the context of stage 5 CKD, there is considerable stress on RBCs due to the accumulation of uremic toxins and increased levels of inflammatory cytokines. Furthermore, these patients often experience a high rate of hemolysis as their weakened kidneys cannot effectively filter the overload of free hemoglobin that results from the destruction of RBCs.
The severe decrease in kidney function (GFR <15 mL/min/1.73 m2) leads to the need for renal replacement therapy, which can further contribute to the reduced lifespan of RBCs due to the mechanical stress of dialysis. Anemia is a common complication of advanced CKD, and the reduced lifespan of RBCs is a contributing factor, along with the reduced production of erythropoietin by the damaged kidneys, leading to decreased RBC production.