Serum Hepcidin Detects Iron Deficiency Anemia in HIV Infected Patients with Anemia of Inflammation

INTRODUCTION: The etiology of HIV- associated anemia is multifactorial. We previously found a high prevalence of anaemia of inflammation and anemia due to micronutrient deficiencies in HIV patients (Eur J Pediatr 2012, 17:531). Inflammatory disease confounds the value of standard diagnostic markers, posing a challenge to the detection of iron deficient and iron-restricted erythropoiesis. Using serum hepcidin as a biomarker, we tested the hypothesis that total body iron stores like inflammatory signals would also influence serum hepcidin levels in patients with HIV infection.

METHODS: Healthy subjects, patients with pure iron deficiency anemia (IDA) andpatients with HIV infection were prospectively enrolled after obtaining informed consent. Using sex adjusted WHO values for anemia diagnosis, ferritin <12µg/L, and CRP values, subjects were categorized into healthy and IDA groups (N Engl J Med 2015, 373:485). Using age adjusted WHO values for anemia, patients with HIV were divided into anemic and non-anemic groups. Using the soluble transferrin receptor (sTfR)/log ferritin (F) index, we defined those subjects with an sTfR-F index < 1.03 as having anemia of inflammation (AI) and those subjects with an sTfR-F index ≥1.03 as having IDA superimposed on AI (Am J Hematol. 2011, 86:923). All laboratory analytes were measured using standard commercial assays.

RESULTS: The demographic characteristics of the different groups in the study population are shown in table 1. Compared with healthy controls, mean hemoglobin was significantly lower in patients with pure IDA, HIV patients with anemia, and HIV patients without anemia (p<0.001). The serum soluble transferin receptor (sTfR) levels and serum erythropoietin levels were significantly elevated in pure IDA patients (p<0.001) and HIV patients with anemia (p<0.001) compared with healthy controls, reflecting erythropoietic stress. Compared with healthy controls, serum hepcidin levels were markedly lower in pure IDA patients (p<0.01) and HIV patients with anemia suggesting that iron status influenced hepcidin levels more profoundly than inflammation in HIV infected patients. We also measured erythrocyte ZPP levels and found them to be significantly higher in pure IDA patients (p<0.001) and HIV patients with anemia (p<0.001) compared to healthy controls. All HIV patients with anemia had an sTfR-F index ≥1.03 suggesting the presence of IDA superimposed on AI. Interestingly, serum hepcidin levels correlated inversely with the sTfR-F index in both patients with pure IDA (ρ=-0.76; p<0.001) and in HIV patients with anemia (ρ=-0.4; p<0.02). Similarly, ZPP levels correlated linearly with the sTfR-F index in pure IDA patients (ρ=0.6; p<0.002) and in HIV patients with anemia (ρ=0.5; p<0.001).

CONCLUSION: Our data shows significant differences in serum hepcidin and erythrocyte ZPP levels in healthy, IDA and HIV patients. These two biomarkers could be included in the panel of diagnostic tests used to detect iron deficiency anemia superimposed on anemia of inflammation. Further studies are needed to provide the appropriate cut-off values with which IDA can be detected with appropriate sensitivity and specificity in patients with anemia of inflammation. Such data may also be helpful in monitoring therapeutic responses to iron.