Phosphate Microvascular Study

August 23, 2018 updated by: Veterans Medical Research Foundation

The Effects of Phosphate on Microvascular Function

Elevated phosphate concentrations in the blood have been associated with multiple negative health outcomes in patients with chronic kidney disease as well as in the general population. These negative outcomes include an increased risk of vascular complications like heart attack and stroke. While complications like heart attack and stroke reflect obstructive disease in large blood vessels, recent evidence suggests that elevated phosphate concentrations may first lead to disease in small blood vessels.

This single site clinical trial will randomize 20 veterans with end stage renal disease on hemodialysis to either a phosphate binder or placebo and evaluated for changes in their microvascular function using laser-Doppler flowmtery and nail-fold capillaroscopy.

Study Overview

Status

Unknown

Conditions

Intervention / Treatment

Detailed Description

Project Background: Recent studies have suggested that increased serum phosphate and phosphate intake may acute impair microvascular blood flow. However, this has never been directly tested using imaging techniques that directly measure microvascular flow. The end-stage renal disease population on hemodialysis at the VA San Diego is an ideal population to evaluate this effect.

Project Question: Does reduction of serum phosphate through the use of a phosphate binder (lanthanum carbonate) increase microvascular blood flow in persons with ESRD? Project Methods: The investigators propose a 4 week, randomized, double-blinded, placebo controlled, single-center, crossover trial. Participants will have their microvascular function assessed at the baseline of the study using laser-Doppler flowmetry and nail-fold capillaroscopy. They will then be randomized to either lanthanum carbonate or placebo for 2 weeks. Microvascular measurements will be repeated at the end of the 2 week period. Participants will then cross-over to the other study arm. After 2 weeks in the other study arm, they will have microvascular measurements repeated and the trial will then be complete. The primary outcome of the study will be the % change in skin blood flow after heating from 31 degrees Celsius to 44 degrees Celsius. This will be compared within each individual after they complete each arm of the study. Changes seen on nail-fold capillaroscopy, acceptability, safety, and adherence will be key secondary outcomes.

Study Type

Interventional

Enrollment (Anticipated)

20

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

21 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Diagnosis of ESRD on hemodialysis (HD) for >90 days.
  • Age >21.
  • Capacity to understand and sign informed consent as assess by principal investigator.
  • On a phosphate binder with stable dose for >2 weeks.
  • Serum phosphate at screening visit of <7.0.

Exclusion Criteria:

  • Pregnancy.
  • Actively breastfeeding.
  • Use of oral contraceptives.
  • Inability to take oral medications.
  • History of medication non-compliance as assessed by the treating physician.
  • Patients currently enrolled in another trial.
  • Planned or expected surgical procedure during study period.
  • Planned or expected hospitalization during study period.
  • Corrected serum calcium greater than 10.2 mg/dl.
  • Serum intact PTH >1000 pg/ml
  • Albumin < 3 g/dl.
  • Allergy or intolerance to lanthanum carbonate.
  • Principal investigator deems patient to be unsuitable.
  • Non-English speaking persons. (Study performed at VA, therefore do not anticipate this represents a significant portion of the population).

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Quadruple

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
No Intervention: Standard
Participants will have their hyperphosphatemia managed with lanthanum carbonate 1 g with meals and 500 mg with snacks as per typical care, for 2 weeks.
Placebo Comparator: Intervention
Participants will take a placebo instead of standard care with a phosphate binder, for 2 weeks.
Other: Withholding standard phosphate binder
In this trial, placebo represents the intervention and not the control. Standard therapy for hyperphosphatemia in end-stage renal disease includes treatment with a phosphate binder. In this trial the intervention will be to withhold the phosphate binder and use placebo instead. In this way the effect of a higher serum phosphate can be evaluated.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
% Change in flux of blood after skin heating to 44 C as measured using laser-Doppler flowmtery.
Time Frame: Performed at initial study visit, at the end of the first arm of the study (Day 14) and again at the end of the second arm of the study (Day 28)
Flux of blood through skin will be measured using a Perimed PF5000. This will be performed at baseline in a temperature controlled room. Baseline skin measurements will be made at 31C. Skin will then be heated to 44 C. The percent change will be the outcome. This outcome will be compared within each person at the conclusion of each arm. Measurements will all be made on the Monday or Tuesday, the day of the participant's first dialysis treatment of the week. Measurements will be made prior to dialysis.
Performed at initial study visit, at the end of the first arm of the study (Day 14) and again at the end of the second arm of the study (Day 28)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in capillary count seen post occlusion from pre occlusion, as determined by nail-fold capillaroscopy.
Time Frame: Performed at initial study visit, at the end of the first arm of the study (Day 14) and again at the end of the second arm of the study (Day 28)
Participants will undergo nail fold capillaroscopy using a CapiScope (KK Technology, Honiton United Kingdom) at baseline and then at the end of each treatment arm. Using a capillarascope a capillary count will be made. After measurement a BP cuff will be inflated to 200 mm Hg occlude flow to a single digit for 1 minute. 30 sec after release the count will be made again. This change will be compared within individuals between measurements made at the completion of each arm in the study. Measurements will all be made on the Monday or Tuesday, the day of the participant's first dialysis treatment of the week. Measurements will be made prior to dialysis. Values at the end of each treatment arm will be compared.
Performed at initial study visit, at the end of the first arm of the study (Day 14) and again at the end of the second arm of the study (Day 28)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Veterans Medical Research Foundation

Collaborators

San Diego Veterans Healthcare System

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Anticipated)

January 1, 2019

Primary Completion (Anticipated)

January 1, 2021

Study Completion (Anticipated)

July 17, 2021

Study Registration Dates

First Submitted

July 9, 2018

First Submitted That Met QC Criteria

July 18, 2018

First Posted (Actual)

July 20, 2018

Study Record Updates

Last Update Posted (Actual)

August 24, 2018

Last Update Submitted That Met QC Criteria

August 23, 2018

Last Verified

August 1, 2018

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • VAH170095

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

Yes

IPD Plan Description

de-identified data may be shared at end of study

IPD Sharing Supporting Information Type

  • Study Protocol
  • Statistical Analysis Plan (SAP)
  • Informed Consent Form (ICF)

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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