Characterization of the anaemia associated with Graves’ disease

Abstract

Background Graves’ disease (GD) is associated with hyperthyroidism. Thyrotoxicosis adversely affects multiple organ systems including haematopoiesis. Anaemia occurring specifically in GD has not been systematically studied previously. Objective To define the prevalence and characteristics of the anaemia associated with GD. Design Eighty‐seven newly diagnosed patients with GD were recruited. Haematological indices, thyroid function and inflammatory parameters were examined at presentation and following successful treatment of hyperthyroidism. Setting Tertiary care academic referral centre. Results Thirty‐three per cent of subjects presented with anaemia. The prevalence of anaemia not attributable to other causes (GD anaemia) was 22%. GD anaemia affected 41·6% (10/24) of men compared to 17·5% of women (11/63). Mean erythropoietin (EPO) levels (15·5 ± 5·3 mIU/ml) were within normal reference limits but significantly higher (P = 0·004) than those of the non‐anaemic controls. Hgb correlated inversely with EPO (P = 0·05) and CRP (P = 0·04) levels, a relationship that persisted after multivariate adjustment for TT3 or TT4. With antithyroid therapy for 16 ± 6·3 weeks, Hgb levels normalized in 8 out of 9 subjects with GD anaemia (10·7 ± 0·8 to 13·5 ± 1·3 g/dl, P = 0·0001). After normalization of Hgb, mean MCV and TIBC were significantly increased, and median ferritin and mean EPO were significantly decreased. Conclusions GD anaemia is common, resembles the anaemia of chronic disease, and is associated with markers of inflammation. It corrects promptly with return to the euthyroid state following treatment.