Dietary Phosphorus Load and Postprandial Serum Phosphate in HD Patients

University College Cork (UCC)

Status: Completed

Conditions: Hemodialysis

Treatments: Other: Standard Diet; Other: Modified Diet

Study type: Interventional

Funder types: Other

Identifiers

NCT04845724

16-CRFC-32

Details and patient eligibility

About

This study is to investigate the acute postprandial effect of a modified versus standard low phosphorus diet on serum phosphate, potassium and intact parathyroid levels in prevalent hemodialysis (HD) patients

Full description

Background: Potential dietary strategies for controlling hyperphosphataemia include the use of protein sources with lower phosphorus bioavailability such as pulses and nuts, focus on phosphorus to protein ratios and the avoidance of all phosphate additives.

Method: Controlled crossover feeding study in 8 HD patients. On one day, participants were directly observed eating a standard low phosphorous diet and on the other day, a modified low phosphorus diet. The modified diet included beef and less dairy, with a lower phosphorus to protein ratio, as well as plant-based protein, whole grains, pulses and nuts containing phytates which reduces phosphorus bioavailability. Both diets were tailored for each participant to provide 1.1g protein/kg ideal body weight. Participants provided fasting bloods before breakfast, a pre-prandial sample before lunch and samples at one hour intervals for the four hours after the meal, for analysis of phosphate, potassium and intact parathyroid hormone (iPTH).

Enrollment: 8 patients

Sex: All

Ages: 18 to 80 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• > 18 years of age;
• on dialysis for > 3 months;
• pre-dialysis serum phosphate < 2.5 mmol/L and
• serum potassium < 6.3 mmol/L on most recent routine monthly blood test;
• urinary outputs of < 200 ml/day by self-report;
• being in their usual state of health

Exclusion criteria

• history of diabetes mellitus
• history of parathyroidectomy
• history of calciphylaxis

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: None (Open label)

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8 participants in 2 patient groups

Standard Diet

Active Comparator group

Description:

The standard diet was based on the current dialysis diet sheet. The standard diet main meal contained a higher proportion of foods with a higher phosphorus to protein ratio (salmon and dairy), and foods with higher phosphorus bioavailability (cake). The diet was tailored for each participant to provide 1.1g protein/kg ideal body weight. The major differences between the diets were at the main meal.

Treatment:

Other: Standard Diet

Modified Diet

Experimental group

Description:

The modified diet, representative of the proposed modified phosphorus diet used food of lower phosphorus to protein ratio such as beef and less dairy. Approximately 30% dietary phosphorus in the modified diet came from foods with significant phytate content such as pulses, nuts and whole grains. The modified diet was tailored for each participant to provide 1.1g protein/kg ideal body weight.

Treatment:

Other: Modified Diet