Iron AbsorptionARIANCT07142590
Determination of Iron Absorption and Losses in People Living at High Altitude to Investigate the Requirements in This Population Group Using a Newly Developed Technique
A study testing Stable Isotopes in people with Iron Absorption and Iron Requirements, run by Diego Moretti at 1 site in Switzerland.
Trial summary
Iron is an essential micronutrient responsible for a whealth of biological processes of the human body. Iron plays a fundamental role especially in oxygen transport, by binding to hemoglobin in the blood circulation. Read more about this study
- Who is it for?
- Ages 18 to 45 yearsHealthy volunteers can take part
- Conditions the study is for
- Iron Absorption, Iron Requirements, Altitude
- What is being tested?
- Stable Isotopes
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 120 participants
- Where
- 1 siteSwitzerland
- Study dates
- 22 Aug 2025to Feb 2028
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 45 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Females and males aged 18-45 y
- BMI: 18 to 25 kg/m2
- Body weight <70 kg for females, <85 kg for males
- Plasma ferritin >25 µg/L
- Signed informed consent
Who cannot join
- Hb <12 g/dL (females), Hb <13 g/dL (males), corrected for altitude using the 2024 WHO guidance values for hemoglobin adjustments
- Inflammation (CRP > 5 mg/L)1
- Plasma ferritin >150 µg/L for females and >200 µg/L for males
- Chronic disease known to affect iron metabolism
- Chronic medications (except for oral contraceptives)
- Pregnancy (tested at screening) or intention to become pregnant during the course of the study
Show all 18Show fewer
- Lactation
- High physical activity (MET-min/week > 3000 calculated according to the IPAQ, short version, administered at the screening)
- Difficulty with blood withdrawal
- Earlier participation in a study using stable iron isotopes or participation in any clinical study within the last 30 days
- Smoking
- Blood donation, blood transfusion or significant blood loss (more than 400 mL) over the past 6 months
- Intention to regularly donate blood during the 2 years duration of the study
- No residence in the respective location/altitude for at least the last 2 years
- No intention to reside in the respective location/altitude at least for the next 2 years
- Participants who are planning to spend an extended period (>12 weeks) at a different altitude from their residence location
- Spending more than 2 nights per week at a different location from residence location
- Inability to understand the information sheet and the informed consent form due to cognitive or language reasons
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Switzerland1 site, 1 recruiting
- Recruiting
Fernfachhochschule Schweiz (FFHS)
Zurich, Canton of Zurich, 8005
About this study
Official title: Iron Balance in Humans Living at High Altitude: Defining Requirements and Optimal Biomarker Thresholds Using a Novel Body Iron Labelling Technique Based on Stable Iron Isotopes.
Iron is an essential micronutrient responsible for a whealth of biological processes of the human body. Iron plays a fundamental role especially in oxygen transport, by binding to hemoglobin in the blood circulation. Iron intake from the diet needs to be in balance the unavoidable losses that occur daily via different pathways. The recommended daily requirement of iron is based on the balance between absorption and losses and is calculated to maintain a balance so that the absorption equals losses. At higher altitudes, the absorption of iron may be higher due to adaptation mechanisms in response to low oxygen concentration, and to maintain a larger erytroid compartement. However, the long-term effects of altitude on iron balance are unknown. Filling this knowledge gap is important to better understand iron deficiency in populations living at high and moderate altitudes. Therefore, the investigators plan to study people that live at two different altitudes and measure iron absorption and losses over the long term. This will be useful to formulate specific recommendations for this population groups, to expand the knowledge base to better prevent iron deficiency in Switzerland but also worldwide. Participants will be asked to consume a dose of stable iron isotopes. After one year from isotope administration, the isotopes will be equally distributed in all body compartments and any change in the isotope abundance with the normal occurring body iron can be detected. From this point onwards, the investigators can observe the iron turnover and calculate iron absorption and losses per unit of time. At 4 different visits blood samples will be taken from each participant.
Read the detailed description
This study compares iron absorption in two population groups residing at different altitudes in Switzerland-one below 1000 meters above sea level and the other above 1500 meters. Additionally, the study aims to determine whether daily iron intake recommendations should be adjusted for high-altitude populations and to establish appropriate thresholds for diagnosing iron deficiency and iron deficiency anemia in these conditions. In each group 60 participants (30 men and 30 women) will be recruited. Each participant will be administered with an oral dose of iron isotopes in the form of ferrous sulphate 57FeSO4 dissolved in water. Ascorbic acid (vitamin C) will be additionally given with the isotope dose to increase the absorption and the enrichment in the body compartments and sirup will be added to the solution to confer a sweet flavour. There will be no other intervention throughout the course of the study.
The investigators will collect blood samples during the second year from study start at a frequency of 4 months for a total of 4 visits, at months 12, 16, 20 and 24. Venous blood samples for the measurement of the isotopic signal will be collected, and at two additional study visits the investigators will also measure hemoglobin using the so-called carbon monoxide (CO) rebreathing method that includes a CO rebreathing into a closed-circuit system in combination with pure oxygen. Before and after the 6 min re-breathing, capillary blood will be collected by finger prick in triplicates. At the study visits with blood withdrawal, the investigators will ask participants to fill questionnaires about dietary intake and physical activity.
- Conditions
- Iron Absorption, Iron Requirements, Altitude
- Being tested
- Stable Isotopes
- Keywords
- iron absorption, altitude, stable iron isotopes, long-term iron balance
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Stable IsotopesDietary supplement
15 mg of stable iron isotopes in the form of ferrous sulphate 57FeSO4 will be orally administered to each participant.
| Study group | Role | What they receive |
|---|---|---|
| Isotopic labeled participants | Experimental | The two groups of participants differ only for their residence location at different altitudes. The intervention (administration of iron isotopes) does not differ among the two groups. Receives: Dietary Supplement: Stable Isotopes |
What is being measured
The primary outcome is the main question the study is designed to answer.
57Fe tracer concentration in the circulation
The measurement of the isotopic tracer concentration in the circulation allows to calculate the lon-term iron absorption in the participants, and the rate of change of the tracer allows to calculate the rate of change of body iron.
Measured: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Secondary outcomes (8)
Hemoglobin mass
Hemoglobin mass will be measured using the CO-rebreathing method. In contrast to hemoglobin concentration, hemoglobin mass is more accurate since it does not depend on blood volume.
Measured: 1 year after isotopic administration and every four months afterwards, for a total of 2 measurements for each participant.
Ferritin concentration
Ferritin concentration in serum, expressed as ug/L will be assessed as an indicator of the iron status.
Measured: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Hepcidin concentration
Hepcidin concentration in serum will be measured as a parameter for the iron status.
Measured: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Serum transferrin receptor concentration
The serum concentration of the transferrin receptor (TfR) will be measure as a biomarker for iron status.
Measured: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Concentration of c-reactive protein (CRP)
Concentration of c-reactive protein (CRP) in mg/L will be measured in serum as a biomarker for inflammation status.
Measured: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Concentration of alpha-1-acid glycoprotein (AGP)
Concentration of serum AGP will be measured as abionarker for inflammation status
Measured: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Concentration of erythropoietin
Erythropoietin (EPO) concentration in whole blood will be measured as a biomarker for erythropoiesis.
Measured: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Concentration of Erythroferrone (ERFE)
Concentration of erythroferrone in serum will be measured as a biomarker for erythropoiesis.
Measured: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Aug 2025
- Study start22 Aug 2025
- Primary completionFeb 2028 (estimated)
- Study completionFeb 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Iron AbsorptionStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Two different groups of people residing at different altitudes will ingest the same amount of stable iron isotopes and during the observational period they will undergo the same measurements.
- Masking
- None (open label)
- Enrolment
- 120 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Diego Moretti
- Sponsor type
- University, hospital or other
- Collaborators
- Swiss Federal Institute of Technology, University of Lausanne
- Responsible party
- Sponsor-investigator, Diego Moretti, Swiss Distance University of Applied Sciences
- Investigators
- Diego Moretti, Prof. Dr., Principal investigator, Fernfachhochschule Schweiz (FFHS), SUPSI
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07142590
- Sponsor's protocol ID
- Iron_ARIA_2024
- Acronym
- ARIA
- Status last verified
- Jan 2026
- First submitted
- 6 Feb 2025
- Last updated
- 14 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 14 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Iron Balance in Humans Living at High Altitude: Defining Requirements and Optimal Biomarker Thresholds Using a Novel Body Iron Labelling Technique Based on Stable Iron Isotopes.
- ClinicalTrials.gov ID
- NCT07142590
- Acronym / sponsor ID
- ARIA / Iron_ARIA_2024
- Conditions
- Iron Absorption, Iron Requirements, Altitude
- Keywords
- iron absorption, altitude, stable iron isotopes, long-term iron balance
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 120 participants (estimated)
- Lead sponsor
- Diego MorettiUniversity, hospital or other
- Collaborators
- Swiss Federal Institute of Technology, University of Lausanne
- Study start
- 22 Aug 2025 (actual)
- Primary completion
- Feb 2028 (estimated)
- Study completion
- Feb 2028 (estimated)
- First posted
- 26 Aug 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Iron is an essential micronutrient responsible for a whealth of biological processes of the human body. Iron plays a fundamental role especially in oxygen transport, by binding to hemoglobin in the blood circulation. Iron intake from the diet needs to be in balance the unavoidable losses that occur daily via different pathways. The recommended daily requirement of iron is based on the balance between absorption and losses and is calculated to maintain a balance so that the absorption equals losses. At higher altitudes, the absorption of iron may be higher due to adaptation mechanisms in response to low oxygen concentration, and to maintain a larger erytroid compartement. However, the long-term effects of altitude on iron balance are unknown. Filling this knowledge gap is important to better understand iron deficiency in populations living at high and moderate altitudes. Therefore, the investigators plan to study people that live at two different altitudes and measure iron absorption and losses over the long term. This will be useful to formulate specific recommendations for this population groups, to expand the knowledge base to better prevent iron deficiency in Switzerland but also worldwide. Participants will be asked to consume a dose of stable iron isotopes. After one year from isotope administration, the isotopes will be equally distributed in all body compartments and any change in the isotope abundance with the normal occurring body iron can be detected. From this point onwards, the investigators can observe the iron turnover and calculate iron absorption and losses per unit of time. At 4 different visits blood samples will be taken from each participant.
Detailed description
This study compares iron absorption in two population groups residing at different altitudes in Switzerland-one below 1000 meters above sea level and the other above 1500 meters. Additionally, the study aims to determine whether daily iron intake recommendations should be adjusted for high-altitude populations and to establish appropriate thresholds for diagnosing iron deficiency and iron deficiency anemia in these conditions. In each group 60 participants (30 men and 30 women) will be recruited. Each participant will be administered with an oral dose of iron isotopes in the form of ferrous sulphate 57FeSO4 dissolved in water. Ascorbic acid (vitamin C) will be additionally given with the isotope dose to increase the absorption and the enrichment in the body compartments and sirup will be added to the solution to confer a sweet flavour. There will be no other intervention throughout the course of the study.
The investigators will collect blood samples during the second year from study start at a frequency of 4 months for a total of 4 visits, at months 12, 16, 20 and 24. Venous blood samples for the measurement of the isotopic signal will be collected, and at two additional study visits the investigators will also measure hemoglobin using the so-called carbon monoxide (CO) rebreathing method that includes a CO rebreathing into a closed-circuit system in combination with pure oxygen. Before and after the 6 min re-breathing, capillary blood will be collected by finger prick in triplicates. At the study visits with blood withdrawal, the investigators will ask participants to fill questionnaires about dietary intake and physical activity.
Study design
- Primary purpose
- Prevention
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Two different groups of people residing at different altitudes will ingest the same amount of stable iron isotopes and during the observational period they will undergo the same measurements.
| Arm | Type | Receives |
|---|---|---|
| Isotopic labeled participants | Experimental | Dietary Supplement: Stable IsotopesThe two groups of participants differ only for their residence location at different altitudes. The intervention (administration of iron isotopes) does not differ among the two groups. |
Who may qualify
- Ages
- 18 to 45 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- Females and males aged 18-45 y
- BMI: 18 to 25 kg/m2
- Body weight <70 kg for females, <85 kg for males
- Plasma ferritin >25 µg/L
- Signed informed consent
Key exclusion criteria (18 listed)
- Hb <12 g/dL (females), Hb <13 g/dL (males), corrected for altitude using the 2024 WHO guidance values for hemoglobin adjustments
- Inflammation (CRP > 5 mg/L)1
- Plasma ferritin >150 µg/L for females and >200 µg/L for males
- Chronic disease known to affect iron metabolism
- Chronic medications (except for oral contraceptives)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Stable Isotopes15 mg of stable iron isotopes in the form of ferrous sulphate 57FeSO4 will be orally administered to each participant. | Dietary supplement | Isotopic labeled participants |
Primary outcome
57Fe tracer concentration in the circulation
Time frame: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
The measurement of the isotopic tracer concentration in the circulation allows to calculate the lon-term iron absorption in the participants, and the rate of change of the tracer allows to calculate the rate of change of body iron.
8 secondary outcomes
Hemoglobin mass
Time frame: 1 year after isotopic administration and every four months afterwards, for a total of 2 measurements for each participant.
Ferritin concentration
Time frame: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Hepcidin concentration
Time frame: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Serum transferrin receptor concentration
Time frame: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Concentration of c-reactive protein (CRP)
Time frame: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Concentration of alpha-1-acid glycoprotein (AGP)
Time frame: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Concentration of erythropoietin
Time frame: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Concentration of Erythroferrone (ERFE)
Time frame: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 14 Jan 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Diego Moretti, Prof. Dr. principal investigator
Fernfachhochschule Schweiz (FFHS), SUPSI
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Stable Isotopes in people with Iron Absorption and Iron Requirements, run by Diego Moretti at 1 site in Switzerland.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 5 inclusion and 18 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 14 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Nora Barloggio (+41 44 512 10 01, nora.barloggio@ffhs.ch), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
57Fe tracer concentration in the circulation (time frame: 1 year after isotopic administration and every four months afterwards, for a total of 4 measurements.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 14 Jan 2026.