Chronic Kidney Disease Mineral and Bone Disorder
Conditions
Keywords
chronic kidney disease, CKD, renal failure, phosphorus, phosphate, intestinal absorption
Brief summary
Chronic kidney disease (CKD) affects approximately 26 million Americans with many more at risk for disease development. Elevated serum phosphorus (P) and related abnormalities in P homeostasis due to progressive loss of kidney function are primary driving forces behind cardiovascular dysfunction and mortality in CKD patients. Intestinal P absorption is an critical aspect in P homeostasis but has been understudied, particularly in the early stages of CKD progression. This study aims to determine P absorption in patients with moderate CKD compared to healthy adults.
Interventions
OTHERPhosphorus Absorption Test
Subjects will undergo a radiophosphorus (P-33) absorption test over two days, that will include an oral administration of P-33 on the 1st day of the test, and an IV administration of P-33 on the 2nd day of the test. P-33 activity from serial serum and urine collections will be determined by scintillation counting, and fractional phosphorus absorption calculated by kinetic modeling.
Sponsors
Purdue University
Study design
Observational model
OTHER
Time perspective
PROSPECTIVE
Eligibility
Sex/Gender
ALL
Age
30 Years to 75 Years
Healthy volunteers
Yes
Inclusion criteria
Inclusion: Men and women ages 30-75 years old, any race Moderate CKD, based on the last set of labs done in the past year, defined as: Glomerular Filtration Rate (GFR) category G3a (eGFR 45-59 mL/min) with A2 or A3 albuminuria or proteinuria by positive dipstick or urine protein/creatinine ratio (UPCR); -or- G3b (eGFR 30-44 mL/min), with or without evidence of albuminuria (any A1-A3) or proteinuria. (Figure 1) -or- Healthy control with no diagnosis or evidence of CKD Female subjects must be post-menopausal, surgically sterile, or confirmed not pregnant by pregnancy test and not breastfeeding. Subjects must be on stable doses of medications (except those noted in
Exclusion criteria
) for at least 6 weeks prior to the study Exclusion: Plans to initiate dialysis within 6 months Labs based on the last set done in the past year: Hypercalcemia defined as serum calcium \> 10.5 mg/dL Hyperkalemic \> 5.5 mg/dL Prescribed a phosphate binder medication Small bowel resection, bariatric surgery. Medically unstable or poorly controlled hypertension, diabetes, or gastrointestinal disorders in the opinion of the physicians on the study team Calcitriol, ergocalciferol, cholecalciferol, vitamin D analogs, calcimimetics, PTH analogues, calcium supplements, multivitamins/mineral and other medications that may alter phosphorus metabolism - must be off for at least 6 weeks prior to study
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Fractional Phosphorus Absorption | Measured from serial blood draws over a 4-hour time frame | Radiophosphorus (P-33) activity determined by liquid scintillation counting in serum and urine after oral and IV administration will be used to determine fractional phosphate absorption. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Serum FGF23 | Measured from baseline measures and serial blood draws over a 4-hour time frame | serum intact and c-terminal FGF23 |
| Serum 1,25(OH)2D | Measured from baseline measures and serial blood draws over a 4-hour time frame | serum 1,25-dihydroxyvitamin D |
| Serum parathyroid hormone (PTH) | Measured from baseline measures and serial blood draws over a 4-hour time frame | serum intact parathyroid hormone |
| Serum phosphate | Measured from baseline measures and serial blood draws over a 4-hour time frame | serum phosphate |
| 24h Urine phosphate | measured from two, 24-hour urine collections | 24h urine phosphate |
Countries
United States
Outcome results
None listed