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Phosphate in Blood Pressure Regulation (Phos-RR)

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT02822131
Recruitment Status : Completed
First Posted : July 4, 2016
Last Update Posted : July 4, 2016
Information provided by (Responsible Party):
Nilufar Mohebbi, University of Zurich

Brief Summary:
High dietary phosphate intake in the general population is associated with a higher risk for developing kidney disease and cardiovascular disease with an increased overall mortality. Whereas the effects of high phosphate intake on general health become clearer, almost nothing is known about underlying mechanisms. More recently, the investigators and others found in animal models that FGF23 stimulates the renal NaCl cotransporter NCC, the target of thiazide diuretics, and that increased NCC activity may increase blood pressure. The investigators could also show that increasing dietary phosphate intake in mice, increases FGF23 and NCC activity within 3 days. Thus, the objective of this single-centre observational cross-over study including 20-45 year old healthy male probands is to elucidate the role of dietary phosphate on blood pressure regulation and renal handling of sodium chloride in healthy subjects. Further the impact of dietary phosphate intake on the regulation of phosphaturic hormones and other factors regulation blood pressure will be investigated. In addition, the investigators will examine whether phosphate intake modulates gut microbiome composition. The primary outcome in this study is the change in blood pressure in healthy subjects on low-phosphate diet compared to healthy subjects on high-phosphate diet. In addition, to assess changes in NCC activity as the main mechanism of phosphate-sensitive blood pressure regulation, renal sodium chloride excretion after administration of hydrochlorothiazide will be measured. The secondary outcomes of this study are: changes in renal phosphate, calcium and potassium excretion, changes in phosphate regulation hormones such as 25-OH-Vit. D, 1,25-(OH)2-Vit. D, PTH, FGF23, dopamine in plasma and urine, changes in plasma and urinary aldosterone levels, changes in sodium/chloride-cotransporter NCC and NaPi-IIa assessed from urinary exosomes, and changes in stool phosphate excretion and gut microbiome composition.

Condition or disease Intervention/treatment Phase
Hypertension Dietary Supplement: sodium phosphate Drug: sevelamer, sodium bicarbonate, sodium chloride Not Applicable

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 10 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)
Primary Purpose: Diagnostic
Official Title: The Effect of Dietary Phosphate Intake on Blood Pressure Regulation and Renal Sodium Chloride Excretion in Healthy Male Volunteers
Study Start Date : January 2016
Actual Primary Completion Date : June 2016
Actual Study Completion Date : June 2016

Resource links provided by the National Library of Medicine

Arm Intervention/treatment
low phosphate
low phosphate will be induced by low phosphate diet and additional treatment with oral phosphate binder sevelamer.
Drug: sevelamer, sodium bicarbonate, sodium chloride
high phosphate
high phosphate diet will be induced by oral supplementation with sodium phosphate.
Dietary Supplement: sodium phosphate

Primary Outcome Measures :
  1. Change in blood pressure [ Time Frame: 5 days ]
  2. Change in renal sodium chloride excretion [ Time Frame: 5 days ]

Information from the National Library of Medicine

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Ages Eligible for Study:   20 Years to 45 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • 20-45 year old healthy male subjects

Exclusion Criteria:

  • - Kidney disease (defined by eGFR < 90 ml/min or microalbuminuria (> 30mg/d))
  • Diabetes mellitus
  • Hypertension (RR > 140/85 mmHg)
  • Hypotension (RR < 90/60 mmHg)
  • any regular medication
  • non-Western type diet e.g. vegetarian, vegan etc.
  • History of kidney stones
  • Allergy to sulphonamides or penicillins
  • Hereditary fructose intolerance
  • known hypersensitivity or allergy to class of drugs used in this study
  • Glaucoma
  • Vitamin D deficiency (< 20 ng/ml)
  • Hyper- or Hypoparathyroidism
  • Hypo- or hyperaldosteronism
  • Participation in any other study

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT02822131

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University Hospital Zurich, Nephrology
Zurich, ZH, Switzerland, 8091
Sponsors and Collaborators
University of Zurich

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Responsible Party: Nilufar Mohebbi, PD Dr. med., University of Zurich Identifier: NCT02822131     History of Changes
Other Study ID Numbers: Phos-RR
First Posted: July 4, 2016    Key Record Dates
Last Update Posted: July 4, 2016
Last Verified: June 2016
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No
Additional relevant MeSH terms:
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Vascular Diseases
Cardiovascular Diseases
Chelating Agents
Sequestering Agents
Molecular Mechanisms of Pharmacological Action