Phosphorus Absorption in Healthy Adults and in Patients With Moderate Chronic Kidney Disease

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