Phosphate Assessment in Chronic Kidney Disease Patients Study

This study is looking at how different levels of phosphorus in your diet affect people with Chronic Kidney Disease (CKD) Stages 3-4. Researchers want to understand how your body handles phosphorus and find new ways to measure if you have too much of it. You would follow a special diet for 21 days where the amount of phosphorus you eat gradually increases. The study will measure your blood phosphate, parathyroid hormone (PTH), and FGF23 levels to see how they change. This study is for men and women aged 18 or older with CKD Stage 3 or 4, meaning your eGFR (a measure of kidney function) is between 15 and 60.

Study design: This is an interventional study planning to enroll 60 participants, with 30 having CKD and 30 without CKD. It involves a 21-day dietary intervention with increasing phosphorus intake.
What's involved: You would follow a special diet for 21 days, with phosphorus intake changing weekly. You would have overnight fasting blood and 24-hour and random urine samples collected at the start and end of each week.
Compensation: Not stated in the trial record.
Follow-up: Your blood and urine levels will be measured at baseline, week 1, week 2, and week 3, which is the end of the dietary intervention.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

Phosphate Assessment in Chronic Kidney Disease Patients Study

Recruiting

NAAges 18+InterventionalDiagnostic

University of Texas Southwestern Medical Center

~60 participants

Updated 2026-01-28 on ClinicalTrials.gov

What's tested:Dietary Phosphorus Intake

At a glance

Recruiting sites

1 of 1 listed site is recruiting right now

RecruitingSuspended, closed, or not yet open

What they're measuring

Change in serum phosphate levels

Measured over Baseline, week 1, week 2, and week 3

+4 more outcomes measured

Conditions

Chronic Kidney Disease (Stage 3-4)

Chronic Kidney Disease Mineral and Bone Disorder

Where it's being run

1 sites across 1 states

Texas1

Study leadership

Jing Chen, MD · PRINCIPAL_INVESTIGATOR · University of Texas Southwestern Medical Center

Who to contact

Alexandra Hartman

[email protected]

214-645-8294

Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

Men or women aged 18 years or older, of any race/ethnicity

Women must either be post-menopausal or have no monthly menstrual cycle

Estimated total daily energy expenditure (TDEE) of 1700 - 2700 calories

eGFR \>15 ml/min/1.73m2 - \< 60 ml/min/1.73m2 for the CKD group (CKD Stage 3 or Stage 4)

eGFR ≥ 60 ml/min/1.73m2 and negative urine protein on dipstick test for the non-CKD group

English speaking

Exclusion

Pregnant, currently breastfeeding, or \<3 months postpartum

Current dialysis or kidney transplant patient

Current use of insulin or chemotherapy drugs

Smokes cigarettes or uses e-cigarettes (vapes)

Uses nicotine products or other recreational drugs

Medical history of stroke or myocardial infarction (MI)

Medical history of conditions that can affect phosphate metabolism (i.e., uncontrolled thyroid disorder, parathyroid disorder, or gastrointestinal malabsorption disorders \[Crohn's, ulcerative colitis, and celiac disease\], cirrhosis)

Current use of certain medications that directly alter phosphate levels (i.e., phosphate binders; phosphate supplements, irregular use of iron)

Regular use of laxatives

Hypo- or hyperphosphatemia (serum phosphate \< 2.5 or \> 4.6 mg/dl)

Hypo- or hypercalcemia (serum calcium \< 8.4 or \> 10.7 mg/dl)

Severe anemia (hemoglobin \< 8 g/dl for women and \< 9 g/dl for men)

Severe hyperglycemia (serum blood glucose \> 300 mg/dl)

Body weight less than \<110 lbs (due to risk for phlebotomy-induced anemia)

Received a blood transfusion in the last four months

Extreme hypertension as demonstrated by a blood pressure \> 180/120 as the average of 3 blood pressures taken during the screening/baseline, or extremely low blood pressure \< 80/50

Unwilling or unable to eat study meals

Lack of access to a functional refrigerator or freezer

Lack of access to a microwave or conventional oven

On low potassium diet

On low phosphate diet

Specific dietary restrictions (i.e. vegetarian, vegan, ketogenic, etc.)

Food allergies including but not limited to milk, egg, soy, nuts, shellfish, and wheat or gluten

Allergic to sodium phosphate

Unable or unwilling to complete urinary sample collection or food diaries

Unable or unwilling to provide informed consent

Unable to read or speak English

Participant in other conflict clinical trial

Unable to complete the study measurements

Unsafe to participate in this study per investigator's judgement

What this trial measures

Change in serum phosphate levelsBaseline, week 1, week 2, and week 3
Circulating serum phosphate levels (mg/dL) will be measured using standard clinical laboratory assays
Change in parathyroid hormone (PTH) levelsBaseline, week 1, week 2, and week 3
Circulating PTH levels (pg/mL) will be measured using standard clinical laboratory assays
Change in C-terminal Fibroblast Growth Factor 23 (FGF23) levelsBaseline, week 1, week 2, and week 3
Circulating C-terminal FGF23 levels (RU/mL) will be measured using standard clinical laboratory assays
Change in Fibroblast Growth Factor 23 (FGF23) levelsBaseline, week 1, week 2, and week 3
Circulating FGF23 levels (pg/mL) will be measured using standard clinical laboratory assays
Phosphate burden indicesBaseline, week 1, week 2, week 3
Phosphate burden indices, developed using machine learning methods to systematically incorporate both known biomarkers and novel biomarkers. No units have been identified, we anticipate creating a score.

Trialytics