Enzyme-linked Immunosorbent Assay to Measure Serum Ferritin and the Relationship between Serum Ferritin and Nonheme Iron Stores in Cats

Abstract

Abstract. Serum ferritin concentration correlates with tissue iron stores in humans, horses, calves, dogs, and pigs but not in rats. Because serum iron and total iron-binding capacity can be affected by disorders unrelated to iron adequacy (such as hypoproteinemia, chronic infection, hemolytic anemia, hypothyroidism, and renal disease), serum ferritin is probably the most reliable indicator of total body iron stores in larger species. To test the hypothesis that serum ferritin might be correlated with tissue iron levels in cats, we developed a quantitative enzyme-linked immunosorbent assay that uses two monoclonal antibodies in a sandwich arrangement to measure feline serum ferritin. The recovery of purified femtin added to feline sera ranged from 94% to 104°/o; the withinassay coefficient of variability was 8.4%, and the assay-to-assay variability was 13.2%. Mean serum ferritin from 40 apparently healthy cats was 76 ng/ml (SD = 24 ng/ml). Serum femtin concentration was significantly correlated (P < 0.00 1, n = 10 1, Y = 0.365) with the nonheme iron in the liver and spleen (expressed as milligrams of iron per kilogram of body weight), as determined by Pearson product-moment correlation analysis. Because serum iron can decrease in diseases other than iron deficiency, the combination of serum iron and serum ferritin should provide sufficient evidence to differentiate anemia of chronic inflammation from anemia of iron deficiency in the cat.

Iron status of cats with chronic kidney disease

“…3,13 Iron stores have been evaluated in the feline liver and spleen and historically feline liver biopsies have been evaluated to assess tissue iron levels; however, this is not a commonly performed diagnostic test because of its invasive nature. 15 A second limitation to this study is that not all enrollees had urinalyses, thyroid levels or abdominal imaging performed and therefore we cannot definitively rule out early chronic kidney disease in these populations of healthy cats and cats with nonrenal illness, or additional nonrenal illness in cats with chronic kidney disease. A third limitation is that we had small, uneven populations with only 2 cases of IRIS stage IV CKD and only 8 anemic CKD cats.…”

“…TIBC is decreased in inflammation thus our results support the presence of inflammation in this population of cats with CKD. [13][14][15][16][17] TSAT and MCV were significantly lower in anemic cats compared to nonanemic cats with chronic kidney disease. These findings are consistent with both an absolute and a functional iron deficiency.…”

“…17 Serum ferritin levels, when evaluated in conjunction with serum iron levels, are the best indicator of total body iron supplies in cats. 15 There is no correlation between tissue iron stores and total iron binding capacity or serum iron concentration. 15 Ferritin concentrations are primarily decreased in absolute iron deficiency anemia and increased in iron overload, hemochromatosis secondary to repeated blood transfusion and systemic inflammatory disease.…”

“…15 There is no correlation between tissue iron stores and total iron binding capacity or serum iron concentration. 15 Ferritin concentrations are primarily decreased in absolute iron deficiency anemia and increased in iron overload, hemochromatosis secondary to repeated blood transfusion and systemic inflammatory disease. 13,17,21 It is an acute phase protein and secretion is stimulated by proinflammatory cytokines including IL-1, IL-6, and TNF-a.…”

Enzyme‐linked immunosorbent assay to quantitate serum ferritin in the northern fur seal (Callorhinus ursinus)

“…Minute amounts of ferritin also circulate in the plasma, and the concentration of serum ferritin correlates with total body iron stores. Serum ferritin is used to estimate total body iron stores in several mammalian species, including humans [Lipschitz et al, 1974], horses [Smith et al, 1984b], cattle [Furugouri et al, 1982], pigs [Smith et al, 1984a], dogs [Weeks et al, 1989], and cats [Andrews et al, 1994]. The relationship between serum ferritin and body iron stores in humans may not be as strong as previously thought; however, of the commonly measured iron analytes (e.g., serum ferritin, serum iron, unsaturated iron-binding capacity, and transferrin saturation), serum ferritin is still the best predictor of body iron stores [Beutler et al, 2002].…”