Anemia is commonly observed in nephritis. It may be so severe that the question arises as to whether the anemia is the primary disease.
Various causes of the anemia of nephritis have been suggested, but comprehensive or conclusive studies have not been made. Grawitz1 maintains that decrease in the blood elements does not take place if cardiac efficiency is maintained. He recognizes two groups of cases of chronic nephritis: (1) those with efficient cardiac function and adequate peripheral circulation, and (2) those with deficient cardiac function and circulatory stasis. In this latter group, either dilution or concentration of the blood plasma takes place. If the plasma is diluted a relative or dilution anemia occurs. Hamelin2 has noted the association of anemia and uremia. He emphasizes the importance of hydremia and of hemotoxic substances in the blood as possible etiologic factors. Ceconi3 did not find decrease in resistance of the erythrocytes
BROWN GE, ROTH GM. THE ANEMIA OF CHRONIC NEPHRITIS. Arch Intern Med (Chic). 1922;30(6):817-840. doi:10.1001/archinte.1922.00110120136009