Background Anaemia is common in left heart failure and is associated with a poorer outcome. Many patients with pulmonary arterial hypertension (PAH) are anaemic or iron-deficient. This study was performed to investigate the prevalence of iron deficiency in PAH and to identify possible causes.
Methods All patients with idiopathic or heritable PAH diagnosed in 1995–2008 were identified. Controls were selected from patients with chronic thromboembolic pulmonary hypertension (CTEPH). Full blood counts were examined and any abnormality was investigated. Patients were excluded if they had a cause for iron deficiency. The prevalence study was based on 85 patients with idiopathic PAH and 120 with CTEPH. A separate group of 20 patients with idiopathic PAH and 24 with CTEPH with matching haemodynamics were prospectively investigated for serum factors affecting iron metabolism.
Results The prevalence study identified a point prevalence of unexplained iron deficiency of 50% in premenopausal women with idiopathic PAH compared with 8% in premenopausal women with CTEPH (p=0.002); 14% in postmenopausal women with idiopathic PAH compared with 6% in postmenopausal women with CTEPH (p=0.16); 28% in men with idiopathic PAH men compared with 2% in men with CTEPH (p=0.002); and 60% in patients with heritable PAH. The serum study showed that patients with idiopathic PAH had lower serum iron and transferrin saturations than those with CTEPH. Interleukin-6 levels correlated with iron levels(r=−0.6, p=0.006) and transferrin saturations (r=−0.68, p=0.001) in idiopathic PAH but not in CTEPH.
Conclusions The prevalence of unexplained iron deficiency is significantly higher in idiopathic PAH than in CTEPH. This may be linked to interleukin-6.
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Funding This work was partly funded by an MRC (UK) (to ES) Research Training Fellowship, the British Heart Foundation, the Cambridge NIHR Biomedical Research Centre and the Sackler studentship.
Competing interests ES has received travel grants from Encysive and GlaxoSmithKline and an unrelated unrestricted research grant from Pfizer. CMT has received travel grants from Actelion. MRT has received travel grants from Encysive and GlaxoSmithKline. RMR has received travel grants from Pfizer and GlaxoSmithKline. KKS has received honoraria from Encysive Pharmaceuticals for an advisory board meeting and travel grants from Actelion, United Therapeutics Corporation, Encysive and GlaxoSmithKline. NWM has received honoraria for educational talks from Actelion and Pfizer and a research grant from Novartis. JP-Z has received honoraria from Actelion, Pfizer, GlaxoSmithKline, Encysive and Schering for speaking at conferences and advisory board meetings. She also holds a joint grant of £75K between Actelion, Pfizer, Schering and United Therapeutics. VM, MB and JA have no competing interests.
Ethics approval This study was conducted with the approval of the Cambridgeshire 3 Research Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.
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