Phosphate in Blood Pressure Regulation

Hypertension Clinical Trial

— Phos-RR  

Official title:

The Effect of Dietary Phosphate Intake on Blood Pressure Regulation and Renal Sodium Chloride Excretion in Healthy Male Volunteers

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT02822131
• Other study ID #: Phos-RR
• Status: Completed
• Phase: N/A
• First received: April 8, 2016
• Last updated: June 29, 2016
• Start date: January 2016
• Est. completion date: June 2016

Study information

• Verified date: June 2016
• Source: University of Zurich
• Contact: n/a
• Is FDA regulated: No
• Health authority: Switzerland: Ethikkommission
• Study type: Interventional

Clinical Trial 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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 10
• Est. completion date: June 2016
• Est. primary completion date: June 2016
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Male
• Age group: 20 Years to 45 Years

Eligibility

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

Study Design

Allocation: Randomized, Intervention Model: Crossover Assignment, Masking: Open Label, Primary Purpose: Diagnostic

Related Conditions & MeSH terms

• Hypertension

Intervention

Dietary Supplement:
• sodium phosphate

Drug:
• sevelamer, sodium bicarbonate, sodium chloride

Locations

Country	Name	City	State
Switzerland	University Hospital Zurich, Nephrology	Zurich	ZH

Sponsors (1)

Lead Sponsor	Collaborator
University of Zurich

Country where clinical trial is conducted

Switzerland, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Change in blood pressure		5 days	No
Primary	Change in renal sodium chloride excretion		5 days	No