Assessing How the Body Responds to Increased Phosphate Intake, and How This Response Depends on Age and Sex.

Assessing Human Phosphate Tolerance and Its Dependency on Age and Sex

Status

Not yet recruiting

Phases

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT07149337

Enrollment

Registered

2025-09-02

Start date

2025-09-30

Completion date

2027-09-30

Last updated

2025-09-02

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Aging, Kidney Disease, Mineral Metabolism

Keywords

Phosphate homeostasis and aging, Oral phosphate challenge

Brief summary

Kidney function declines with age and this could affect phosphate balance after an acute phosphate load (increased phosphate intake). In daily life, we regularly experience acute phosphate loads through our diet. The aim of this clinical study is to determine whether the body's response to increased phosphate intake changes with age and whether there are sex differences in this response.

Detailed description

Forty subjects (males and females aged 18-25 or 63-70) will ingest an oral phosphate load, after which their body's response will be assessed by collecting blood and urine samples over a period of ten hours.

Interventions

OTHEROral phosphate load

Participants ingest an oral phosphate load containing 558 mg of phosphorus once.

Study design

Allocation

Intervention model

SINGLE_GROUP

Primary purpose

BASIC_SCIENCE

Masking

NONE

Eligibility

Sex/Gender

ALL

Age

25 Years to 70 Years

Healthy volunteers

Yes

Inclusion criteria

* Healthy volunteers 18-25 and 63-70 years old * 18.5 ≥ BMI \< 26 kg/m2 * 0.84 ≥ phosphate in plasma ≤ 1.45 mM * 2.20 ≥ calcium in plasma ≤ 2.50 mM * 15 ≥ PTH in plasma ≤ 65 pg/ml * eGFR ≥ 60 ml/min/1-73 m2 * 90 ≥ Systolic blood pressure ≤ 140 mmHg * 60 ≥ Diastolic blood pressure ≤ 85 mmHg * No hematuria and no acute urinary tract infection * Ability and willingness to participate in the study * Voluntary signed inform consent

Exclusion criteria

* Diabetes mellitus * Pregnancy * History of kidney stones * History of parathyroidectomy * History of anorexia nervosa * History of bulimia * History of solid organ transplantation. * Nephrolithiasis * Sarcoidosis * Chronic pancreatitis * Chronic diarrhea * Chronic liver disease * Complete distal renal acidosis (dRTA) * Cystinuria * Hypo- or hyperaldosteronism * Hyper- or hypotension * Hypernatremia * Gastrointestinal disorders * Known hypersensitivity reactions to azoic dyes, acetylsalicylic acid, as well as antirheumatic drugs and painkillers (prostaglandin synthesis inhibitors). Intake of vitamin D and calcium supplements, phosphate, bisphosphonates, cinacalcet, denusomab, teriparatide, systemic glucocorticoids or mineralcorticoids, antiepileptics, carboanydrase inhibitors or diuretics

Design outcomes

Primary

Measure	Time frame	Description
Phosphate in plasma	The primary outcome will be measured 5 hours after the first blood collection on the day of the study and 4 hours after ingesting the oral phosphate load.	Phosphate in plasma 4 hours after the oral phosphate load shows age differences

Contacts

Primary ContactCarsten A Wagner, Prof. MD

carsten.wagner@physiol.uzh.ch41 44 635 50 23

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026