Low Phosphate Diets in Patients With Early Stages of Chronic Kidney Disease

Not Applicable

Completed

Interventions: Drug: Lanthanum Carbonate
Dietary Supplement: Low Phosphorus Diet
Dietary Supplement: Unrestricted Phosphorus Diet
Drug: Placebo

Brief Summary: The purpose of this study is to learn more about how the kidneys control the blood levels of phosphorus in patients with early chronic kidney disease. The ultimate goal is to use this information to design improved treatment strategies for phosphorus-related problems for the millions of patients with chronic kidney disease.

Detailed Description: Phosphorus is a mineral found in dairy products, nuts, and meat that is essential for bone health and many other important functions inside the body's cells. The kidneys are responsible for keeping the blood levels of phosphorus normal. Healthy kidneys do this by spilling excess phosphorus into the urine. In patients with chronic kidney disease, the kidneys are unable to spill an adequate amount of phosphorus so that excess phosphorus can accumulate in the walls of blood vessels leading to heart disease, their leading cause of death. A recently discovered hormone called FGF-23 helps control the blood levels of phosphorus by "telling" the kidney how much phosphorus to spill in the urine. The purpose of this study is to learn more about how FGF-23 helps the kidneys control the blood levels of phosphorus. The ultimate goal is to use this information to design improved treatment strategies for phosphorus-related problems for the millions of patients with chronic kidney disease.

Recruitment & Eligibility

Inclusion Criteria

Exclusion Criteria

subjects with rapidly advancing renal failure who thus might develop hyperphosphatemia or end stage renal disease requiring initiation of dialysis during the study period
subjects expected to require dialysis initiation within the follow up period
subjects with hyperphosphatemia > 4.6 mg/dL
subjects with any previous or current treatment with phosphate binders or active vitamin D (doxercalciferol or calcitriol)
subjects with malnutrition, defined as a serum albumin < 3.0 mg/dl, in order to avoid worsening protein-malnutrition status during the restricted study period since phosphate restricted diets are also low in protein
subjects with chronic gastrointestinal diseases that could impede their absorptive ability such as Crohn's disease, ulcerative colitis and sprue
subjects with liver disease (ALT or AST > 100 U/L) or cholestasis (direct bilirubin > 1.0 mg/dl) because this can limit their ability to absorb fat soluble vitamins such as vitamin D
subjects with anemia, defined as a hematocrit <27% at the screening visit
subjects wht have been hospitalization within the previous 4 weeks
subjects who are pregnant
subjects who are breastfeeding mothers
subjects with primary hypoparathyroidism
subjects with primary hyperparathyroidism
subjects with previous subtotal parathyroidectomy
subjects with previous outpatient counseling by a renal nutritionist
subjects who are unable to independently provide written informed consent - prisoners, mentally incompetent, minors

Arm && Interventions

Group	Intervention	Description
Lanthanum Carbonate and Low Phosphorus Diet	Lanthanum Carbonate	25% of subjects will receive binders plus a phosphate restricted diet.
Lanthanum Carbonate and Low Phosphorus Diet	Low Phosphorus Diet	25% of subjects will receive binders plus a phosphate restricted diet.
Lanthanum Carbonate and Unrestricted Phosphorus Diet	Unrestricted Phosphorus Diet	25% binders + unrestricted phosphate diet.
Placebo and Low Phosphorus Diet	Low Phosphorus Diet	25% placebo + phosphate restricted diet.
Placebo and Low Phosphorus Diet	Placebo	25% placebo + phosphate restricted diet.
Placebo and Unrestricted Phosphorus Diet	Unrestricted Phosphorus Diet	25% placebo + unrestricted phosphate diet.
Placebo and Unrestricted Phosphorus Diet	Placebo	25% placebo + unrestricted phosphate diet.
Lanthanum Carbonate and Unrestricted Phosphorus Diet	Lanthanum Carbonate	25% binders + unrestricted phosphate diet.