Effects of Vitamin D Replacement on Hormones Regulating Iron Metabolism in Individuals With Chronic Kidney Disease

August 21, 2015 updated by: University of Alabama at Birmingham

Vitamin D Replacement in Chronic Kidney Disease and Its Effects on Iron Homeostasis, Serum Hepcidin, and Hemojuvelin Levels.

The purpose of the study is to learn more about how treatment with vitamin D can affect iron metabolism and blood levels of two hormones that control iron levels, hepcidin and hemojuvelin in people with chronic kidney disease (CKD).

Iron is an essential mineral which is a major component of proteins that carry oxygen in the blood. Problems with iron metabolism can lead to low blood levels (anemia), which can commonly happen in people with CKD.

New research over the last decade has uncovered a new hormone called 'hepcidin', which is made in the liver and released into the blood. Hepcidin controls how much iron is in the blood by preventing the absorption of iron from food. Blood levels of hepcidin C are found to be high in people with CKD, and a recent small study in people with normal kidney function showed that treatment with vitamin D decreased hepcidin levels.

Another protein, known as 'hemojuvelin', has been recently discovered and is also thought to control the amount of iron in the blood. The relationship between vitamin D and hemojuvelin has never been studied before.

In this study, investigators would like to examine the effects of vitamin D on iron metabolism and blood levels of hepcidin C and hemojuvelin in individuals with CKD.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Iron homeostasis is tightly regulated in humans. Iron is mostly recycled from hemoglobin, myoglobin and other enzymes. Since humans lack the capacity to excrete excess iron, it must be intricately regulated at the site of its absorption in the duodenum and proximal jejunum. In the last decade, hepcidin has emerged as a master regulator of iron homeostasis. It decreases iron absorption from the gut mucosa by limiting its transport from the enterocyte across the basolateral membrane into the circulation. It does so by down-regulating the synthesis or promoting internalization of a basolateral membrane protein 'Ferroportin', the only known cellular iron exporter.

Vitamin D is hypothesized to exert a significant and independent effect on the iron metabolism. In the CKD population, low vitamin-D levels independently correlate with the severity of anemia. Hepcidin C levels are found to be elevated in the CKD population. Mechanisms underlying the effect of vitamin D on iron homeostasis potentially include vitamin D induced expression of erythropoietin receptors, increased proliferation of erythroid precursors, and reduction in hepcidin C levels due to reduction in IL-6 from the anti-inflammatory effects of vitamin D. More recently, a study revealed direct relationship between vitamin D replacement and a sustained fall in hepcidin C levels. The same group of researchers found the above relationship to be due to a direct effect of vitamin D on hepcidin expression.

Hemojuvelin (HJV) is a protein encoded by the HFE2 gene and is found in the membrane bound and the soluble form (sHJV) in the humans. Mutations in the HJV gene are responsible for Juvenile Hemochromatosis. It is an upstream regulator of hepcidin transcription and appears to be essential for hepcidin expression in the hepatocytes and has important role to play in iron homeostasis. Recently, an assay has become available to measure the sHJV levels in the serum.

Although, we know that hepcidin plays a central role in iron homeostasis and recent studies have given us insight into the role hemojuvelin and vitamin D play in iron metabolism, to date, no studies have examined the effect on vitamin D replacement on hepcidin, hemojuvelin levels and iron metabolism in individuals with CKD.

Hypothesis 1: Treatment with an activated vitamin D analog in the individuals with CKD results in a statistically significant fall in hepcidin C levels as compared to individuals provided with placebo.

Hypothesis 2: Treatment with an activated vitamin D analog results in decreased levels of soluble hemojuvelin in individuals with chronic kidney disease.

Hypothesis 3: Vitamin D replacement in the individuals with CKD results in improved iron parameters as compared to the placebo.

Study Type

Interventional

Enrollment (Actual)

40

Phase

  • Early Phase 1

Contacts and Locations

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

Study Locations

  • United States
    • Alabama
      • Birmingham, Alabama, United States, 35294
        • University of Alabama

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

19 years and older (ADULT, OLDER_ADULT)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Patients with mild to moderate CKD (eGFR 15 - 60 ml/min/1.73 m2) as estimated by the CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) formula.

Exclusion Criteria:

  • Subjects currently receiving active vitamin D analog therapy or history of recent (< 3 months) use.
  • Subjects currently receiving nutritional vitamin D (cholecalciferol or ergocalciferol) in dosages greater than 2000 IU/day.
  • Subjects receiving erythropoiesis stimulating agents.
  • Subjects receiving intravenous iron therapy.
  • Subjects receiving oral iron therapy started within 3 months prior to recruitment.
  • Subjects with severe anemia defined as Hb < 8.0 g/dL for males and Hb <7.0 g/dL for females.
  • Subjects with iron deficiency anemia defined as serum ferritin <100ng/ml and Transferring Saturation < 20%.
  • Pregnancy and lactation.
  • Subjects with hypercalcemia defined as serum calcium level of > 10.0 mg/dL.
  • Subjects with serum phosphorus concentration of > 4.5 mg/dL.
  • Subjects with acute kidney injury or rapidly declining GFR.
  • Subjects receiving any form of renal replacement therapy including hemodialysis, peritoneal dialysis, and patients with renal transplant.
  • Subjects with focus of active inflammation or infection determined clinically.

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

  • Allocation: RANDOMIZED
  • Interventional Model: PARALLEL
  • Masking: QUADRUPLE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
EXPERIMENTAL: Oral Calcitriol
Oral Calcitriol 0.5 mcg once daily for 6 weeks
Drug: Oral Calcitriol 0.5 mcg once daily for 6 weeks
Other Names:
  • Rocaltrol
PLACEBO_COMPARATOR: Placebo Arm
Placebo capsule 1 Capsule once daily for 6 weeks
Drug: Placebo

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in serum hepcidin levels
Time Frame: At Day 0, Day 3, 1 week, 4 weeks and 6 weeks
At Day 0, Day 3, 1 week, 4 weeks and 6 weeks
Change in soluble hemojuvelin
Time Frame: At Day 0, Day 3, 1 week, 4 weeks and 6 weeks
At Day 0, Day 3, 1 week, 4 weeks and 6 weeks
Change in other indices of iron metabolism
Time Frame: At Day 0, Day 3, 1 week, 4 weeks and 6 weeks
Including, Serum Ferritin, Iron level, Percent transferrin saturation and TIBC
At Day 0, Day 3, 1 week, 4 weeks and 6 weeks

Secondary Outcome Measures

Outcome Measure
Time Frame
Change in serum hemoglobin
Time Frame: At Day 0, Day 3, 1 week, 4 weeks and 6 weeks
At Day 0, Day 3, 1 week, 4 weeks and 6 weeks

Collaborators and Investigators

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

Sponsor

University of Alabama at Birmingham

Investigators

  • Principal Investigator: Bhupesh Panwar, MD, University of Alabama, Nephrology Division
  • Study Director: Orlando M Gutierrez, MD,MMSc, University of Alabama, Nephrology Division

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

October 1, 2013

Primary Completion (ACTUAL)

June 1, 2015

Study Completion (ACTUAL)

June 1, 2015

Study Registration Dates

First Submitted

November 4, 2013

First Submitted That Met QC Criteria

November 19, 2013

First Posted (ESTIMATE)

November 20, 2013

Study Record Updates

Last Update Posted (ESTIMATE)

August 24, 2015

Last Update Submitted That Met QC Criteria

August 21, 2015

Last Verified

August 1, 2015

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • F130725013

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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