Iron supplementation in iron deficiency

INTERVENTION: 1. Seeking consent, followed by a medical history and examination 2. Subjective symptom assessment 3. Blood test 4. Spirometry 5. Echocardiography 6. Acute hypoxic exposure with measurement of oxygen saturations, endtidal carbondioxide and breathing 7. Insertion of intravenous cannula 8. Infusion of saline (carried out if patient is randomised to the control limb) 9. Infusion of iron (carried out in all patients randomised to the test limb, and also at the end of the study offered to those who had been randomised to the control limb, as a therapeutic intervention) 10. Actigraphy (wearing small movement sensors like wrist watches around the ankles during sleep). Carried out in the participant's own home. Study drug: Iron Carboxymaltose, up to 1000mg, once only. CONDITION: Iron deficiency ; Haematological Disorders ; Iron deficiency anaemia PRIMARY OUTCOME: Acute hypoxic PASP post‐ compared to pre‐iron infusion, measured at days 1, 2, 8 and 15. SECONDARY OUTCOME: Measured at weeks 1, 2, 4 and 8:; 1. Time course of euoxic and hypoxic PASP post‐iron infusion; 2. Erythropoietin, and acute hypoxic cardiac output and ventilation post‐ compared to pre‐iron infusion; 3. Incidence of restless legs syndrome in iron deficient patients and iron replete healthy volunteers, and changes in symptoms and nocturnal leg movements following an iron infusion; 4. Magnitude and time course of relief of fatigue post‐iron infusion INCLUSION CRITERIA: 1. Willing and able to give informed consent for participation in the study 2. Men and women aged 18 ‐ 50 years and generally in good health 3. Detectable tricuspid regurgitation on echocardiography (enabling measurement of pulmonary arterial pressure) For iron deficient patients: 4. Iron deficiency, defined as a ferritin less than 15 µg/L For iron replete healthy volunteers: 5. Normal iron status (for example ferritin greater than 40 µg/L, iron 20 ‐ 150 ng/ml, total iron binding capacity 250 ‐ 450 ng/ml, and transferrin saturation 20 ‐ 50%)