Carrier StateNCT06847256
Genetic Risk Factor for Heat Stroke
An observational study of Carrier State and Heat Stroke, run by University of Iowa at 1 site in United States.
Trial summary
The goal of this observational study is to examine the effect of the Cystic Fibrosis (CF) Carrier state on the risk for dehydration and other CF-specific fluid-and-electrolyte disorders in male and female adults. Read more about this study
- Who is it for?
- Ages 18 to 60 years
- Conditions the study is for
- Carrier State, Heat Stroke, Dehydration
- What is being tested?
- Heat Challenge
- Type of treatment
- Surgery or procedure
- How many people
- 200 participants
- Where
- 1 siteUnited States
- Study dates
- 19 Nov 2025to Dec 2026
- Phase
- Observational
- 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 60 years
- All sexes
- No healthy volunteers
- Adult
Study population: Individuals who have previously been genotyped as CF Carriers or Controls.
Who may be able to join
- Previously genotyped as a CF carrier or control
- Comfortable speaking/reading English
Who cannot join
- Previously genotyped as a CF patient
- Diagnosis of Type 1 or Type 2 diabetes
- History of heart attack, stroke, heart failure, or atherosclerosis
- Currently pregnant
- Currently taking beta blockers or diuretics
- Prisoner status
- Unable to provide own written informed consent
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
University of Iowa Health Care
Iowa City, Iowa, 52242
Shelby L Francis, PhD, 319-678-8037, shelby-francis@uiowa.edu
Aaron Miller, PhD
About this study
Official title: Exploring a Common Genetic Risk Factor for Heat Stroke and Dehydration
The goal of this observational study is to examine the effect of the Cystic Fibrosis (CF) Carrier state on the risk for dehydration and other CF-specific fluid-and-electrolyte disorders in male and female adults.
The primary aim of the study is to estimate the risk of electrolyte disorders attributable to the CF carrier state in a genotyped cohort.
Read more
This will be accomplished with two smaller projects- Aim 1 and Aim 2.
Aim 1 will consist of 100 CF Carriers and 100 age- and sex-matched controls. Participants in this aim will be asked to complete a Participant Info and Temperature Survey consisting of questions about race, ethnicity, medical history, and how they experience heat.
Aim 2 will consist of a subset of 25 CF Carriers and 25 age- and sex-matched controls from Aim 1. Participants in this aim will be scheduled for a visit to complete a heat challenge. At this visit, they will also complete the Participant Info and Temperature Survey. They will also sit in a sauna at 62 - 63 degrees Celsius for 45 minutes.
- Conditions
- Carrier State, Heat Stroke, Dehydration
- Being tested
- Heat Challenge
- Medical subject headings
- Heat Stroke, Dehydration
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Heat ChallengeProcedure or surgery
Participants will be asked to arrive well-hydrated and to refrain from exercise, alcohol, caffeine, and smoking for 24 hours prior to the visit. Height, weight, blood pressure, and body fat percentage will be measured. Blood (15.5 ml) and urine will be collected. Participants will wear a heart rate monitor and sit in a heat chamber at 62-63 degrees Celsius for 45 minutes. Heart rate will be measured continuously. Body temperature and a self-report of their comfort (1-4 scale) and thermosensation (1-7 scale) will be measured before the challenge, every 15 minutes during the challenge, and after the challenge. During the challenge, a sample of sweat will be collected to measure electrolyte loss. Participants will consume 16 ounces of water at their own pace during the 45 minutes. If they become too uncomfortable to continue or their body temperature rises above 39 degrees Celsius, the challenge will be stopped. All baseline measures except body fat percentage will be measured again.
| Study group | Role | What they receive |
|---|---|---|
| CF Carriers | Participants who have previously been genotyped as CF Carriers. Receives: Procedure: Heat Challenge | |
| Controls | Participants who have previously been genotyped as controls and are age- and sex-matched to a CF Carrier. Receives: Procedure: Heat Challenge |
What is being measured
The primary outcome is the main question the study is designed to answer.
Participant Scores for Temperature Sensitivity and Regulation Survey
Individual and composite scores for 5 components of the Temperature Sensitivity Survey (Heat- and Activity-Induced Autonomic Thermoregulation; Heat-Induced Behavioral Thermoregulation; Heat Perception; and Heat- and Activity-Induced Fatigue). For these 5 components, there are a total of 25 questions. All questions are on a 7-point scale, with the highest representing the most sensitive to heat and the lowest being the least sensitive. We will add up the scores for each question to arrive at a composite score for each component and the component scores will be added to arrive at a total score. Scores will be compared between groups.
Measured: Baseline
Change in Weight
Weight will be measured in kilograms pre- and post-heat challenge. We will compare change in weight between groups.
Measured: Up to 45 minutes
Change in Sodium Concentration
Sodium concentration will be measured pre- and post-heat challenge by blood draw and urine sample. Sodium concentration will be compared between groups.
Measured: Up to 45 minutes
Change in Potassium Concentration
Potassium concentration will be measured pre- and post-heat challenge by blood draw and urine sample. Potassium concentration will be compared between groups.
Measured: Up to 45 minutes
Concentration of Sweat Chloride
Sweat chloride will be measured pre- and post-heat challenge by sweat collection. Sweat chloride will be compared between groups.
Measured: Up to 45 minutes
Final Score on Comfort Scale
Participants will rate their level of comfort on a scale of 1-4 at the end of the heat challenge. Scores will be compared between groups.
Measured: Up to 45 minutes
Final Score on Thermosensation Scale
Participants will rate their level of thermosensation on a scale of 1-7 at the end of the heat challenge. Scores will be compared between groups.
Measured: Up to 45 minutes
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted26 Feb 2025
- Study start19 Nov 2025
- Primary completionDec 2026 (estimated)
- Study completionDec 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Carrier StateStudies 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
- Observational
- Observational model
- Case-control
- Time perspective
- Prospective
- Enrolment
- 200 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Iowa
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Aaron C. Miller, University of Iowa
- Investigators
- Aaron Miller, PhD, Principal investigator, University of Iowa
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06847256
- Sponsor's protocol ID
- 202308319
- Status last verified
- Apr 2026
- First submitted
- 14 Feb 2025
- Last updated
- 27 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 27 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Exploring a Common Genetic Risk Factor for Heat Stroke and Dehydration
- ClinicalTrials.gov ID
- NCT06847256
- Acronym / sponsor ID
- 202308319
- Conditions
- Carrier State, Heat Stroke, Dehydration
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 200 participants (estimated)
- Lead sponsor
- University of IowaUniversity, hospital or other
- Study start
- 19 Nov 2025 (actual)
- Primary completion
- Dec 2026 (estimated)
- Study completion
- Dec 2026 (estimated)
- First posted
- 26 Feb 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.
The goal of this observational study is to examine the effect of the Cystic Fibrosis (CF) Carrier state on the risk for dehydration and other CF-specific fluid-and-electrolyte disorders in male and female adults.
The primary aim of the study is to estimate the risk of electrolyte disorders attributable to the CF carrier state in a genotyped cohort.
This will be accomplished with two smaller projects- Aim 1 and Aim 2.
Aim 1 will consist of 100 CF Carriers and 100 age- and sex-matched controls. Participants in this aim will be asked to complete a Participant Info and Temperature Survey consisting of questions about race, ethnicity, medical history, and how they experience heat.
Aim 2 will consist of a subset of 25 CF Carriers and 25 age- and sex-matched controls from Aim 1. Participants in this aim will be scheduled for a visit to complete a heat challenge. At this visit, they will also complete the Participant Info and Temperature Survey. They will also sit in a sauna at 62 - 63 degrees Celsius for 45 minutes.
Study design
- Observational model
- Case-control
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| CF Carriers | – | Procedure: Heat ChallengeParticipants who have previously been genotyped as CF Carriers. |
| Controls | – | Procedure: Heat ChallengeParticipants who have previously been genotyped as controls and are age- and sex-matched to a CF Carrier. |
Who may qualify
- Ages
- 18 to 60 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
- Study population
- Individuals who have previously been genotyped as CF Carriers or Controls.
Key inclusion criteria (2 listed)
- Previously genotyped as a CF carrier or control
- Comfortable speaking/reading English
Key exclusion criteria (7 listed)
- Previously genotyped as a CF patient
- Diagnosis of Type 1 or Type 2 diabetes
- History of heart attack, stroke, heart failure, or atherosclerosis
- Currently pregnant
- Currently taking beta blockers or diuretics
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 |
|---|---|---|
| Heat ChallengeParticipants will be asked to arrive well-hydrated and to refrain from exercise, alcohol, caffeine, and smoking for 24 hours prior to the visit. Height, weight, blood pressure, and body fat percentage will be measured. Blood (15.5 ml) and urine will be collected. Participants will wear a heart rate monitor and sit in a heat chamber at 62-63 degrees Celsius for 45 minutes. Heart rate will be measured continuously. Body temperature and a self-report of their comfort (1-4 scale) and thermosensation (1-7 scale) will be measured before the challenge, every 15 minutes during the challenge, and after the challenge. During the challenge, a sample of sweat will be collected to measure electrolyte loss. Participants will consume 16 ounces of water at their own pace during the 45 minutes. If they become too uncomfortable to continue or their body temperature rises above 39 degrees Celsius, the challenge will be stopped. All baseline measures except body fat percentage will be measured again. | Procedure or surgery | CF Carriers, Controls |
Primary outcome
Participant Scores for Temperature Sensitivity and Regulation Survey
Time frame: Baseline
Individual and composite scores for 5 components of the Temperature Sensitivity Survey (Heat- and Activity-Induced Autonomic Thermoregulation; Heat-Induced Behavioral Thermoregulation; Heat Perception; and Heat- and Activity-Induced Fatigue). For these 5 components, there are a total of 25 questions. All questions are on a 7-point scale, with the highest representing the most sensitive to heat and the lowest being the least sensitive. We will add up the scores for each question to arrive at a composite score for each component and the component scores will be added to arrive at a total score. Scores will be compared between groups.
Change in Weight
Time frame: Up to 45 minutes
Weight will be measured in kilograms pre- and post-heat challenge. We will compare change in weight between groups.
Change in Sodium Concentration
Time frame: Up to 45 minutes
Sodium concentration will be measured pre- and post-heat challenge by blood draw and urine sample. Sodium concentration will be compared between groups.
Change in Potassium Concentration
Time frame: Up to 45 minutes
Potassium concentration will be measured pre- and post-heat challenge by blood draw and urine sample. Potassium concentration will be compared between groups.
Concentration of Sweat Chloride
Time frame: Up to 45 minutes
Sweat chloride will be measured pre- and post-heat challenge by sweat collection. Sweat chloride will be compared between groups.
Final Score on Comfort Scale
Time frame: Up to 45 minutes
Participants will rate their level of comfort on a scale of 1-4 at the end of the heat challenge. Scores will be compared between groups.
Final Score on Thermosensation Scale
Time frame: Up to 45 minutes
Participants will rate their level of thermosensation on a scale of 1-7 at the end of the heat challenge. Scores will be compared between groups.
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 27 Apr 2026.
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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.
Aaron Miller, PhD principal investigator
University of Iowa
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Carrier State and Heat Stroke, run by University of Iowa at 1 site in United States.
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 2 inclusion and 7 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 27 Apr 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 United States. 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 Aaron Miller, PhD ((319) 335-3053, aaron-miller@uiowa.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Participant Scores for Temperature Sensitivity and Regulation Survey (time frame: Baseline). The study lists 7 primary outcomes in all. 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 27 Apr 2026.