Low serum levels of prohepcidin, but not hepcidin-25, are related to anemia in familial amyloidosis TTR V30M

Familial amyloidosis TTR V30M (FAP-I) usually presents as a sensorimotor and autonomic neuropathy. Anemia was first described in this disease more than 20 years ago and classified as an anemia of chronic disease. However, so far no studies have addressed the role of inflammatory proteins in this disease. The anemia affects 24.8% of symptomatic FAP-I Portuguese patients, and is associated with low serum erythropoietin levels, independently of the presence of clinical nephropathy. In this study we evaluate the role of systemic inflammation on the erythropoietin production and anemia genesis in FAP-I. Data from 24 FAP-I patients (50% with anemia) and 33 healthy controls were analysed. Laboratory data included hemoglobin, hematocrit, ferritin, transferrin saturation, soluble transferrin receptors (sTR), prohepcidin, hepcidin-25, C-reactive protein (CRP), interleukin-6 and erythropoietin levels. In general, FAP-I patients presented significantly lower hemoglobin, hematocrit and observed/expected erythropoietin levels. Mean sTR was lower in FAP-I patients than in controls (2.36 ± 1.3 vs 2.96 ± 0.8 mg/l, P = 0.055) correlating with hemoglobin and hematocrit. As expected, sTR were positively correlated with erythropoietin both in controls and in FAP-I patients. No significant differences on CRP, interleukin-6, transferrin saturation, ferritin and hepcidin-25 were found between anemic and non-anemic FAP-I patients and between non-anemic FAP-I patients and healthy controls. In all groups, a positive correlation was observed between hepcidin-25 and ferritin. Surprisingly, significantly lower prohepcidin levels were found in FAP-I patients, with or without anemia, not correlated with serum hepcidin-25 levels. In general, the decreased observed/expected EPO levels in FAP-I correlated with the prohepcidin levels, therefore raising the possibility that a common defect in these two hormones may be somehow involved in the genesis of the disease.