Calcium and Phosphorus Whole-Body Balance and Kinetics in Patients With Moderate Chronic Kidney Disease

University of Minnesota (UMN)

Status: Completed

Conditions: Chronic Kidney Diseases; Phosphorus and Calcium Disorders; Chronic Kidney Disease Mineral and Bone Disorder

Treatments: Other: Low Phosphorus Diet; Other: High Phosphorus Diet

Study type: Interventional

Funder types: Other

Identifiers

NCT04019379

1809583731

Details and patient eligibility

About

This pilot study aims to develop a method for simultaneous whole-body calcium and phosphorus balance and full kinetic modeling of both ions in patients with chronic kidney disease.

Full description

The goal of this project is to produce preliminary data on the effects of the commonly prescribed dietary phosphorus restriction on whole-body Calcium (Ca) and Phosphorus (P) balance and kinetics patients with CKD, to support a larger future clinical study. The specific aims are to determine intestinal Ca and P fractional absorption and 2) Ca and P balance and full kinetics, effect sizes variance estimates in patients with CKD on a low Ca diet with high P diet versus dietary P restriction. The hypothesis is that a high P diet, in the context of a typical low Ca diet, leads to P retention negative Ca balance, and that dietary P restriction modestly reduces P retention but does not negative Ca balance.

The study design is a randomized 2-period cross-over study. All outpatient and inpatient visits place at the Indiana CTSI Clinical Research Center located in IU Health University Hospital in Indianapolis, IN. Subjects will be randomly assigned to controlled diets of either low Ca/high P (LCa/HP) or low (LCa/LP) for a 1-week, outpatient diet equilibration period, followed by 1-week inpatient full balance that includes a 48-hour Ca and P absorption testing protocol. After a 1-3 week washout subjects will crossover to the other diet regimen

Enrollment: 3 patients

Sex: All

Ages: 30 to 75 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Men or women, ages 30-75 years old, any race or ethnicity
• Moderate chronic kidney disease
• Female subjects must be postmenopausal (>12 months since last menstrual period), surgically sterile, or confirmed not pregnant by pregnancy test
• Must be on stable doses of medications (except those noted in exclusion criteria) for at least 4 weeks prior to the study
• Willing to discontinue nutritional supplements (e.g. vitamin D, calcium, multivitamin/minerals, or others) upon enrollment until completion of the study
• Adequate vitamin D status defined as serum 25D > 20 ng/mL

Exclusion criteria

• Plans to initiate dialysis within 6 months
• Hypercalcemia defined as serum calcium >10.5 mg/dL within past 3 months
• Hyperkalemia defined as serum potassium >5.5 mg/dL within past 3 months
• Hyperphosphatemia defined as serum phosphate >5.5 mg/dL within past 3 months
• Intestinal disease that alters absorption or normal intestinal function including celiac disease, small bowel resection, or bariatric surgery
• Serious, uncontrolled underlying systemic disease including diabetes, lupus, hypertension
• Pregnant or breastfeeding
• Prescribed a phosphate binder medication, calcitriol, vitamin D analogs, calcimimetics, parathyroid hormone analogues, and other medications that may alter Ca and P metabolism within past 30 days

Trial design

Primary purpose: Basic Science

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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3 participants in 2 patient groups

Sequence A

Experimental group

Description:

High Phos crossover to Low Phos

Treatment:

Other: High Phosphorus Diet

Other: Low Phosphorus Diet

Sequence B

Experimental group

Description:

Low Phos crossover to High Phos

Treatment:

Other: High Phosphorus Diet

Other: Low Phosphorus Diet