Clinical trial NCT02020785: Study of Dietary Additive Phosphorus on Proteinuria and Fibroblast Growth Factor-23
Official title: Randomized Cross-over Study Examining the Effects of Phosphorus Additives on Urinary Albumin Excretion and Fibroblast Growth Factor-23
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Albuminuria
Keywords: proteinuria
Lead sponsor: Geisinger Clinic
Sponsor class: OTHER
Collaborators: name: Johns Hopkins University
First posted: 2013-12-25
Enrollment: 31
Sex: ALL
Minimum age (years): 21
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: TREATMENT

Brief summary: Phosphorus-based food additives are commonly used by food manufacturers for many applications, such as enhancing flavor, in ready-to-eat foods and beverages. While these additives can significantly increase an individual's daily phosphorus intake, little is known about the effect of dietary phosphorus on kidney health. In this study, the investigators will first lower baseline phosphorus intake to about 1000mg/d by educating participants to avoid foods with phosphorus additives. Then, participants will be randomized to a higher phosphorus period (\~2gm/d) and a lower phosphorus period (\~1gm/d) by providing unaltered, commercially-available food/beverage products with and without phosphorus additives.

The investigators hypothesize that participants will have higher urine albumin excretion and fibroblast growth factor-23 (FGF-23) during the higher phosphorus period compared to the lower phosphorus period.

Detailed description: The Study of Dietary Additive Phosphorus on Proteinuria and FGF-23 (SODA-POP) was a single-center, randomized, double-blind, two-period cross-over study that examined the effect of higher vs. lower phosphorus intake for 3 week periods, achieved by addition of commercially available diet beverages and breakfast bars to diet on albuminuria and fibroblast growth factor 23, in adults with presumed early chronic kidney disease (estimated glomerular filtration rate \>= 45 ml/min/1.73m2; and urine albumin/creatinine ratio \>=17 mg/g for men or \>=25 mg/g for women).

Eligibility criteria: Inclusion Criteria:

Adults at least 21 years of age with at least microalbuminuria

Exclusion Criteria:

Estimated glomerular filtration rate \<45ml/min/1.73m2, poorly controlled diabetes or hypertension, nephrotic syndrome, hyperparathyroidism, Paget's Disease, multiple myeloma, uncontrolled thyroid disease, chronic antacid use, use of phosphorus binders, phosphorus supplements, or high-dose vitamin D, inability to complete feeding study, investigator discretion

Primary outcomes:
measure: 24-hour Urine Albumin Excretion
timeFrame: 3 weeks
measure: Fibroblast Growth Factor-23 (FGF-23)
timeFrame: 3 weeks
Secondary outcomes:
measure: Systolic Blood Pressure
timeFrame: 2-3 weeks
measure: Diastolic Blood Pressure
timeFrame: 2-3 weeks
Other outcomes:
Locations:
city: Baltimore
country: United States
facility: Prohealth Clinical Research Unit
state: Maryland
Study officials:
affiliation: Geisinger Clinic
name: Alex R Chang, MD, MS
role: PRINCIPAL_INVESTIGATOR
affiliation: Johns Hopkins University
name: Lawrence J Appel, MD, MPH
role: STUDY_DIRECTOR
References:
citation: Chang A, Batch BC, McGuire HL, Vollmer WM, Svetkey LP, Tyson CC, Sanguankeo A, Anderson C, Houston J, Appel LJ. Association of a reduction in central obesity and phosphorus intake with changes in urinary albumin excretion: the PREMIER study. Am J Kidney Dis. 2013 Nov;62(5):900-7. doi: 10.1053/j.ajkd.2013.04.022. Epub 2013 Jun 28.