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FGF23 and Angiotensin-(1-7) in Hypophosphatemia (GAP)

NCT03489993 · Status: COMPLETED · Type: OBSERVATIONAL · Enrollment: 8

Last updated 2022-08-05

No results posted yet for this study

Summary

Hereditary hypophosphatemia encompasses rare genetic conditions characterized by renal phosphate wasting. Increased circulating levels of fibroblast growth factor 23 (FGF23), a key regulator of phosphorus metabolism, are critical to the pathophysiology of these diseases, most notably in X-linked hypophosphatemia (XLH). Increased FGF23 induces hypertrophy and scarring in the heart in part via stimulating the traditional renin-angiotensin system (RAS) pathway, angiotensin-converting enzyme (ACE)/angiotensin (Ang ll), particularly in patients with chronic kidney disease, but the effect of FGF23 on the heart in patients with FGF23-related hypophosphatemic diseases is unknown. In addition, the relationship between FGF23 and the angiotensin-converting enzyme 2 (ACE2)/angiotensin-(1-7) (Ang-(1-7) pathway of the RAS is unknown.

The objective of this study is to describe the relationship between FGF23, which causes low phosphorus levels, and components of the RAS in the blood and urine to help the investigators understand why the disease occurs and how to better treat it.

Subjects will be identified by querying the Electronic Medical Record according to medical diagnosis. Thirty subjects, 2-24 years of age, will be recruited from the tertiary care Pediatric Endocrinology and Pediatric Nephrology clinics at Brenner Children's Hospital. Inclusion criteria include a confirmed diagnosis of hereditary FGF23-related hypophosphatemia. Clinical data will be obtained from the Electronic Medical Record. Each subject will undergo study assessments at baseline, 6 months and 1 year that include blood work, an echocardiogram, and blood pressure measurements.

The primary hypothesis is that subjects with higher Ang-(1-7) levels have lower rates of cardiac hypertrophy and thus are protected against high FGF23 levels. The secondary hypothesis is that subjects with higher Ang-(1-7) levels have lower systolic blood pressure.

Conditions

  • Hypophosphatemia
  • X-linked Hypophosphatemia
  • Renin-angiotensin System
  • Left Ventricular Hypertrophy

Interventions

DIAGNOSTIC_TEST

Ang II and Ang-(1-7)

Measured in plasma and urine using radioimmunoassays.

DIAGNOSTIC_TEST

FGF23 and klotho

Measured using ELISA's.

Sponsors & Collaborators

  • Wake Forest University Health Sciences

    lead OTHER

Principal Investigators

  • Andrew M South, MD MS · Wake Forest University Health Sciences

Eligibility

Min Age
2 Years
Max Age
24 Years
Sex
ALL
Healthy Volunteers
No

Timeline & Regulatory

Start
2018-12-06
Primary Completion
2020-12-23
Completion
2020-12-23

Countries

  • United States

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT03489993 on ClinicalTrials.gov