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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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ClinicalTrials.gov Identifier: NCT00764816
Recruitment Status : Completed
First Posted : October 2, 2008
Last Update Posted : June 23, 2011
Sponsor:
Information provided by:
Indiana University

Tracking Information
First Submitted Date  ICMJE October 1, 2008
First Posted Date  ICMJE October 2, 2008
Last Update Posted Date June 23, 2011
Study Start Date  ICMJE October 2008
Actual Primary Completion Date February 2011   (Final data collection date for primary outcome measure)
Current Primary Outcome Measures  ICMJE
 (submitted: October 1, 2008)
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 ]
Original Primary Outcome Measures  ICMJE Same as current
Change History Complete list of historical versions of study NCT00764816 on ClinicalTrials.gov Archive Site
Current Secondary Outcome Measures  ICMJE
 (submitted: October 1, 2008)
  • 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 ]
  • 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 ]
Original Secondary Outcome Measures  ICMJE Same as current
Current Other Pre-specified Outcome Measures Not Provided
Original Other Pre-specified Outcome Measures Not Provided
 
Descriptive Information
Brief Title  ICMJE Effect of Dietary Protein Source on Phosphaturia, PTH and FGF23 in Patients With CKD 3 and 4
Official Title  ICMJE Effect of Dietary Protein Source on Phosphaturia, PTH and FGF23 in Patients With CKD 3 and 4
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

  1. if the dietary protein source affects fasting serum and urinary phosphorus excretion
  2. if the protein source affects post prandial changes in serum and urinary phosphorus in patients
  3. 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).

Study Type  ICMJE Interventional
Study Phase  ICMJE Not Applicable
Study Design  ICMJE Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)
Primary Purpose: Basic Science
Condition  ICMJE Chronic Kidney Disease
Intervention  ICMJE
  • Other: grain (soy) protein diet
    The patient is to eat a grain (soy) protein diet for 7 days. The food is prepared by a registered dietitian.
  • Other: casein (meat) protein diet
    The patient is to eat a casein (meat) protein diet for 7 days. The food is prepared by a registered dietitian.
Study Arms  ICMJE
  • Active Comparator: 1 grain (soy) protein diet:
    The patient is to eat a grain (soy) protein diet for 7 days. The food is prepared by a registered dietitian.
    Intervention: Other: grain (soy) protein diet
  • Active Comparator: 2 casein (meat) protein diet
    The patient is to eat a casein (meat) protein diet for 7 days. The food is prepared by a registered dietitian.
    Intervention: Other: casein (meat) protein diet
Publications * 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.

*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Recruitment Information
Recruitment Status  ICMJE Completed
Actual Enrollment  ICMJE
 (submitted: October 1, 2008)
9
Original Estimated Enrollment  ICMJE Same as current
Actual Study Completion Date  ICMJE February 2011
Actual Primary Completion Date February 2011   (Final data collection date for primary outcome measure)
Eligibility Criteria  ICMJE

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
Sex/Gender  ICMJE
Sexes Eligible for Study: All
Ages  ICMJE 18 Years and older   (Adult, Older Adult)
Accepts Healthy Volunteers  ICMJE No
Contacts  ICMJE Contact information is only displayed when the study is recruiting subjects
Listed Location Countries  ICMJE United States
Removed Location Countries  
 
Administrative Information
NCT Number  ICMJE NCT00764816
Other Study ID Numbers  ICMJE 0807-03
Has Data Monitoring Committee No
U.S. FDA-regulated Product Not Provided
IPD Sharing Statement  ICMJE Not Provided
Responsible Party Sharon M. Moe, MD, Indiana University Department of Medicine
Study Sponsor  ICMJE Indiana University
Collaborators  ICMJE Not Provided
Investigators  ICMJE
Principal Investigator: Sharon M Moe, MD Indiana University School of Medicine
PRS Account Indiana University
Verification Date June 2011

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP