An observational study in Carrier State, Heat Stroke and Dehydration, sponsored by University of Iowa. Recruiting at 1 site in United States. Open to participants aged 18 Years to 60 Years. Per ClinicalTrials.gov, last updated 2026-04-27.
Sponsored by University of Iowa · Observational
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.
21 studies on the registry are indexed under Heat Stroke; 10 are open to participants now.
Browse Heat Stroke studies →University of Iowa is the lead sponsor of 279 studies on the registry; 33 are open to participants now.
Of its 45 completed or terminated interventional studies of FDA-regulated products, 40 (89%) have results posted.
Counted across the registry records on this site, refreshed daily.
Individuals who have previously been genotyped as CF Carriers or Controls.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants who have previously been genotyped as CF Carriers.
Procedure: Heat Challenge
Participants who have previously been genotyped as controls and are age- and sex-matched to a CF Carrier.
Procedure: Heat Challenge
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.
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.
Time frame: Baseline
Change in Weight
Weight will be measured in kilograms pre- and post-heat challenge. We will compare change in weight between groups.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: Up to 45 minutes
Started Nov 2025 (actual). Primary completion is estimated for Dec 2026, 13 months after the start.
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