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Effect of Dietary Protein Source on Phosphaturia, PTH and FGF23 in Patients With CKD 3 and 4

Primary Purpose

Chronic Kidney Disease

Status
Completed
Phase
Not Applicable
Locations
United States
Study Type
Interventional
Intervention
grain (soy) protein diet
casein (meat) protein diet
Sponsored by
Indiana University
About
Eligibility
Locations
Arms
Outcomes
Full info

About this trial

This is an interventional basic science trial for Chronic Kidney Disease focused on measuring Chronic kidney disease, stages 3 and 4, phosphaturia, phosphorus, PTH, FGF23, Dietary protein source

Eligibility Criteria

18 Years - undefined (Adult, Older Adult)All SexesDoes not accept healthy volunteers

Inclusion Criteria:

  • age >18 years
  • eGFR 20-45 by modified MDRD equation
  • protein/creatinine ratio <5
  • blood pressure <150/95
  • not taking calcium binder or supplements, vitamin D, or phosphate binders
  • normal serum phosphorus and calcium corrected for albumin and intact PTH <100pg/ml
  • medically stable
  • able to give informed consent and come for all visits

Exclusion Criteria:

  • history of significant liver disease or cirrhosis
  • medically unstable
  • unable to tolerate diets

Sites / Locations

  • Indiana University School of Medicine

Arms of the Study

Arm 1

Arm 2

Arm Type

Active Comparator

Active Comparator

Arm Label

1 grain (soy) protein diet:

2 casein (meat) protein diet

Arm Description

The patient is to eat a grain (soy) protein diet for 7 days. The food is prepared by a registered dietitian.

The patient is to eat a casein (meat) protein diet for 7 days. The food is prepared by a registered dietitian.

Outcomes

Primary Outcome Measures

To determine if the dietary protein source affects fasting serum and urinary phosphorus excretion in patients with CKD stages 3 and 4.

Secondary Outcome Measures

To determine if the protein source affects post prandial changes in serum and urinary phosphorus in patients with CKD stages 3 and 4.
To determine if changes in plasma FGF23 and PTH correlate with urinary phosphorus excretion in response to different protein sources in patients with CKD stages 3 and 4.

Full Information

First Posted
October 1, 2008
Last Updated
June 22, 2011
Sponsor
Indiana University
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1. Study Identification

Unique Protocol Identification Number
NCT00764816
Brief Title
Effect of Dietary Protein Source on Phosphaturia, PTH and FGF23 in Patients With CKD 3 and 4
Official Title
Effect of Dietary Protein Source on Phosphaturia, PTH and FGF23 in Patients With CKD 3 and 4
Study Type
Interventional

2. Study Status

Record Verification Date
June 2011
Overall Recruitment Status
Completed
Study Start Date
October 2008 (undefined)
Primary Completion Date
February 2011 (Actual)
Study Completion Date
February 2011 (Actual)

3. Sponsor/Collaborators

Name of the Sponsor
Indiana University

4. Oversight

Data Monitoring Committee
No

5. Study Description

Brief Summary
Phosphorus is a substance in the blood that comes from food and is normally cleared from the body by the kidneys. In patients with kidney disease, excess phosphorus may build up in the body as you eat. This leads to problems with bones and blood vessels over time. In this study, we will compare the blood and urine before and after eating one week of a diet with a protein from plants (soy and grains) and before and after another one week of diet with protein from animals (meat and dairy products). The amount of phosphorus that the kidney puts out in the urine, and the changes in blood hormones in response to the diet will be measured at the beginning and end of each week on the two diets.
Detailed Description
Chronic Kidney Disease-Mineral Bone disorder (CKD-MBD) is a constellation of problems related to alterations in mineral and bone homeostasis that occur in CKD stage 3-5D (estimated GFR 60-15 ml/min). The damaged kidney is unable to fully excrete a phosphorus load, leading to a compensatory secondary hyperparathyroidism to attempt to increase urinary phosphorus excretion in order to maintain serum phosphorus in the normal range. Eventually this compensation of elevated PTH becomes pathologic and leads to abnormalities in biochemistries, bone and vascular disease, all of which are associated with morbidity and mortality in patients with CKD. Prevention of these complications is key to improved patient outcomes. Unfortunately, this normal or high normal phosphorus does not reflect the "behind the scenes" appropriate and inappropriate compensation. The use of medication to bind phosphorus from food (phosphate binders) may prevent absorption of phosphorus across the intestine and prevent or change the elevations in PTH and other hormones like FGF23. Thus, either urinary excretion of phosphorus, or changes in hormone may be more appropriate end points to evaluate efficacy of phosphate binders than is serum phosphorus. In healthy individuals, there is variation throughout the day (diurnal) in serum phosphorus and urine phosphorus excretion, but in dialysis patients, this variability appears to be lost. No data exists for patients with stage 3 and 4 (pre-dialysis) CKD. Intestinal phosphorus absorption is also dependent on bioavailability (amount of free phosphorus available to be absorbed), which differs depending on the protein source, as the phosphorus in grain/soy diets is less bioavailable than that from protein from animal/casein protein source. In our animal model of CKD, these differences in bioavailability impact urinary phosphorus excretion and serum levels of FGF-23, but not PTH. As phosphaturia, PTH, and FGF23 may become important end points for future clinical trials, understanding diurnal variability and the relationship to diet in patients with CKD 3 and 4 with normal serum phosphorus levels is critical. We hypothesize that dietary protein source will affect the hormonal response and diurnal phosphorus homeostasis in advanced CKD. To test this hypothesis, we will examine the following specific aims in a population of CKD stage 3 and 4 subjects from the Indiana University Affiliated Nephrology Clinics and determine if the dietary protein source affects fasting serum and urinary phosphorus excretion if the protein source affects post prandial changes in serum and urinary phosphorus in patients if changes in plasma FGF23 and PTH correlate with urinary phosphorus excretion in response to different protein sources. We will conduct a cross over study to assess blood and urine after one week of a diet that differs only in the source of the protein (and thus the bioavailability of phosphorus).

6. Conditions and Keywords

Primary Disease or Condition Being Studied in the Trial, or the Focus of the Study
Chronic Kidney Disease
Keywords
Chronic kidney disease, stages 3 and 4, phosphaturia, phosphorus, PTH, FGF23, Dietary protein source

7. Study Design

Primary Purpose
Basic Science
Study Phase
Not Applicable
Interventional Study Model
Crossover Assignment
Masking
None (Open Label)
Allocation
Randomized
Enrollment
9 (Actual)

8. Arms, Groups, and Interventions

Arm Title
1 grain (soy) protein diet:
Arm Type
Active Comparator
Arm Description
The patient is to eat a grain (soy) protein diet for 7 days. The food is prepared by a registered dietitian.
Arm Title
2 casein (meat) protein diet
Arm Type
Active Comparator
Arm Description
The patient is to eat a casein (meat) protein diet for 7 days. The food is prepared by a registered dietitian.
Intervention Type
Other
Intervention Name(s)
grain (soy) protein diet
Intervention Description
The patient is to eat a grain (soy) protein diet for 7 days. The food is prepared by a registered dietitian.
Intervention Type
Other
Intervention Name(s)
casein (meat) protein diet
Intervention Description
The patient is to eat a casein (meat) protein diet for 7 days. The food is prepared by a registered dietitian.
Primary Outcome Measure Information:
Title
To determine if the dietary protein source affects fasting serum and urinary phosphorus excretion in patients with CKD stages 3 and 4.
Time Frame
6 months after baseline
Secondary Outcome Measure Information:
Title
To determine if the protein source affects post prandial changes in serum and urinary phosphorus in patients with CKD stages 3 and 4.
Time Frame
6 months from baseline
Title
To determine if changes in plasma FGF23 and PTH correlate with urinary phosphorus excretion in response to different protein sources in patients with CKD stages 3 and 4.
Time Frame
6 months from baseline

10. Eligibility

Sex
All
Minimum Age & Unit of Time
18 Years
Accepts Healthy Volunteers
No
Eligibility Criteria
Inclusion Criteria: age >18 years eGFR 20-45 by modified MDRD equation protein/creatinine ratio <5 blood pressure <150/95 not taking calcium binder or supplements, vitamin D, or phosphate binders normal serum phosphorus and calcium corrected for albumin and intact PTH <100pg/ml medically stable able to give informed consent and come for all visits Exclusion Criteria: history of significant liver disease or cirrhosis medically unstable unable to tolerate diets
Overall Study Officials:
First Name & Middle Initial & Last Name & Degree
Sharon M Moe, MD
Organizational Affiliation
Indiana University School of Medicine
Official's Role
Principal Investigator
Facility Information:
Facility Name
Indiana University School of Medicine
City
Indianapolis
State/Province
Indiana
ZIP/Postal Code
46202
Country
United States

12. IPD Sharing Statement

Citations:
PubMed Identifier
21183586
Citation
Moe SM, Zidehsarai MP, Chambers MA, Jackman LA, Radcliffe JS, Trevino LL, Donahue SE, Asplin JR. Vegetarian compared with meat dietary protein source and phosphorus homeostasis in chronic kidney disease. Clin J Am Soc Nephrol. 2011 Feb;6(2):257-64. doi: 10.2215/CJN.05040610. Epub 2010 Dec 23.
Results Reference
result

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Effect of Dietary Protein Source on Phosphaturia, PTH and FGF23 in Patients With CKD 3 and 4

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