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NCT Number: NCT06847256

Genetic Risk Factor for Heat Stroke

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.

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Key information

Conditions

Carrier State Dehydration Heat Stress Disorders Heat Stroke Metabolic Diseases Nutritional and Metabolic Diseases Pathologic Processes Pathological Conditions, Signs and Symptoms Water-Electrolyte Imbalance Wounds and Injuries

Age range

18 year–60 year

Sex eligibility

All sexes

Study type

Observational

Primary location

University of Iowa Health Care

Iowa City, Iowa, 52242, United States

Location status: Recruiting

Location contact

Aaron Miller, PhD

PRINCIPAL_INVESTIGATOR

Shelby L Francis, PhD

CONTACT

[email protected]

319-678-8037

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Previously genotyped as a CF carrier or control
  • Comfortable speaking/reading English

Exclusion criteria

  • 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

Treatment and study plan

Heat Challenge

Procedure

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.

Primary outcomes

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

Study contacts

Contact information is provided by the study sponsor or research team.

Aaron Miller, PhD

CONTACT

[email protected]

(319) 335-3053

Shelby L Francis, PhD

CONTACT

[email protected]

319-678-8037

Sponsors and collaborators

Lead sponsor

University of Iowa

Other

Registry information

Official study title

Exploring a Common Genetic Risk Factor for Heat Stroke and Dehydration

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Feb 26, 2025
Registry last updated
Apr 27, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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