Iron Status and Hypoxic Pulmonary Vascular Responses

NCT ID: NCT01847352

Last Updated: 2016-05-06

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

NA

Total Enrollment

31 participants

Study Classification

INTERVENTIONAL

Study Start Date

2013-02-28

Study Completion Date

2014-04-30

Brief Summary

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On exposure to hypoxia (low oxygen) the normal response is for pulmonary arterial systolic blood pressure (PASP, blood pressure through the lungs) to increase. We have previously shown that raising iron by giving an infusion of iron into a vein reduces this pressure rise and that lowering iron by giving a drug that binds iron, magnifies this response. This is potentially a clinically important observation since iron-deficient people may be at increased risk of pulmonary hypertension if exposed transiently or permanently to hypoxia due to lung disease or residence at high altitude; furthermore if this were true then intravenous iron could be an important treatment in this patient group in the event of hypoxic exposure. The observed effects of iron on PASP are likely to be because iron levels affect oxygen sensing. Low iron levels make the body behave as if exposed to low oxygen by inhibiting the breakdown of the family of oxygen-sensing transcription factors, 'hypoxia inducible factor' or HIF. This includes one of the body's normal responses to low oxygen levels - raising blood pressure through the lungs.

This study will answer the question (1) do iron-deficient volunteers have a greater rise in PASP with hypoxia than those who are iron-replete, and (2) does giving intravenous iron cause a greater reduction in the rise in PASP in those who are iron-deficient than iron-replete? The purpose of this study is not to test the safety or clinical efficacy of iron which is already known.

Detailed Description

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Conditions

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Lung Hypoxia Pulmonary Arterial Hypertension Iron Deficiency

Study Design

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Allocation Method

NON_RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

SINGLE

Participants

Study Groups

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Iron-deficient

Healthy volunteers meeting iron-deficient entry criteria; Intravenous administration of ferric carboxymaltose; Subacute hypoxic exposures

Group Type OTHER

Intravenous administration of ferric carboxymaltose

Intervention Type DRUG

Intravenous administration of ferric carboxymaltose 15mg/kg up to a maximum dose of 1000mg

Subacute hypoxic exposures

Intervention Type OTHER

Exposure to six hours of isocapnic hypoxia with end-tidal partial pressure of oxygen clamped at 55 Torr, with and without prior iron infusion

Iron-replete

Healthy volunteers meeting iron-replete entry criteria; Intravenous administration of ferric carboxymaltose; Subacute hypoxic exposures

Group Type OTHER

Intravenous administration of ferric carboxymaltose

Intervention Type DRUG

Intravenous administration of ferric carboxymaltose 15mg/kg up to a maximum dose of 1000mg

Subacute hypoxic exposures

Intervention Type OTHER

Exposure to six hours of isocapnic hypoxia with end-tidal partial pressure of oxygen clamped at 55 Torr, with and without prior iron infusion

Interventions

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Intravenous administration of ferric carboxymaltose

Intravenous administration of ferric carboxymaltose 15mg/kg up to a maximum dose of 1000mg

Intervention Type DRUG

Subacute hypoxic exposures

Exposure to six hours of isocapnic hypoxia with end-tidal partial pressure of oxygen clamped at 55 Torr, with and without prior iron infusion

Intervention Type OTHER

Other Intervention Names

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Ferinject Hypoxia Hypoxic challenge

Eligibility Criteria

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Inclusion Criteria

* Willing and able to give informed consent for participation in the study
* Men and women aged 18 years or older and generally in good health
* Detectable tricuspid regurgitation on echocardiography during both normoxia and hypoxia enabling measurement of pulmonary arterial pressure
* For iron-deficient volunteers: ferritin ≤15microg/L and transferrin saturation \<16%
* For iron-replete volunteers: ferritin ≥20microg/L and transferrin saturation ≥20%

Exclusion Criteria

* Haemoglobin \<8.0g/dl
* Haemoglobinopathy
* Iron overload defined as ferritin \>300microg/L
* Hypoxia at rest or on walking (SaO2 \<94%) or significant comorbidity that may affect haematinics, pulmonary vascular or ventilatory responses, e.g. current infection, a chronic inflammatory condition, known cardiovalvular lesion or pulmonary hypertension, uncontrolled asthma or chronic obstructive pulmonary disease
* Exposure to high altitude (\>2,500m) within the previous six weeks or air travel \>4 hours within the previous week
* Iron supplementation or blood transfusion within the previous 6 weeks
* Pregnancy or breast feeding
Minimum Eligible Age

18 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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National Institute for Health Research, United Kingdom

OTHER_GOV

Sponsor Role collaborator

British Heart Foundation

OTHER

Sponsor Role collaborator

University of Oxford

OTHER

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Principal Investigators

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Annabel H Nickol, MBBS PhD

Role: PRINCIPAL_INVESTIGATOR

University of Oxford

Locations

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University of Oxford Department of Physiology, Anatomy and Genetics

Oxford, Oxfordshire, United Kingdom

Site Status

Countries

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United Kingdom

References

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Smith TG, Balanos GM, Croft QP, Talbot NP, Dorrington KL, Ratcliffe PJ, Robbins PA. The increase in pulmonary arterial pressure caused by hypoxia depends on iron status. J Physiol. 2008 Dec 15;586(24):5999-6005. doi: 10.1113/jphysiol.2008.160960. Epub 2008 Oct 27.

Reference Type BACKGROUND
PMID: 18955380 (View on PubMed)

Smith TG, Talbot NP, Privat C, Rivera-Ch M, Nickol AH, Ratcliffe PJ, Dorrington KL, Leon-Velarde F, Robbins PA. Effects of iron supplementation and depletion on hypoxic pulmonary hypertension: two randomized controlled trials. JAMA. 2009 Oct 7;302(13):1444-50. doi: 10.1001/jama.2009.1404.

Reference Type BACKGROUND
PMID: 19809026 (View on PubMed)

Talbot NP, Smith TG, Privat C, Nickol AH, Rivera-Ch M, Leon-Velarde F, Dorrington KL, Robbins PA. Intravenous iron supplementation may protect against acute mountain sickness: a randomized, double-blinded, placebo-controlled trial. High Alt Med Biol. 2011 Fall;12(3):265-9. doi: 10.1089/ham.2011.1005.

Reference Type BACKGROUND
PMID: 21962070 (View on PubMed)

Balanos GM, Dorrington KL, Robbins PA. Desferrioxamine elevates pulmonary vascular resistance in humans: potential for involvement of HIF-1. J Appl Physiol (1985). 2002 Jun;92(6):2501-7. doi: 10.1152/japplphysiol.00965.2001.

Reference Type BACKGROUND
PMID: 12015365 (View on PubMed)

Frise MC, Cheng HY, Nickol AH, Curtis MK, Pollard KA, Roberts DJ, Ratcliffe PJ, Dorrington KL, Robbins PA. Clinical iron deficiency disturbs normal human responses to hypoxia. J Clin Invest. 2016 Jun 1;126(6):2139-50. doi: 10.1172/JCI85715. Epub 2016 May 3.

Reference Type RESULT
PMID: 27140401 (View on PubMed)

Related Links

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Other Identifiers

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12/SC/0710

Identifier Type: -

Identifier Source: org_study_id

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