Pathophysiology of Uric Acid Nephrolithiasis
Aim 1A: Measurement of renal cortical fat content in kidney surgical specimen. A cross-sectional study to compare anthropometric and renal acid-base parameters with renal cortical fat content, measured histochemically and biochemically on kidney surgical specimen. Our hypothesis predicts positive correlation between functional parameters and renal fat content.
Aim 1B. Measurement of renal cortical fat content by magnetic resonance spectroscopy. A cross-sectional study to correlate renal triglyceride content measured spectroscopically using MRS with urinary acid-base profile evaluated during a detailed inpatient metabolic study.
Aim 2: Prospective, longitudinal, randomized, double-blind, placebo controlled study to determine the effects of 6 months of treatment with pioglitazone, 30 mg daily compared with placebo on renal fat content and its correlation to urinary acid-base parameters.
Aim 1a: Both genders, all ethnicities, age > 21 years undergoing a nephrectomy for RCC.
IUAN subjects: Adult subjects with IUAN, age > 21 years of either sex, of any ethnicity.
Overweight and obese non-stone forming subjects: Adult subjects, gender-matched, age-matched (within 10 years), and weight-matched (within 10% of body weight) to IUAN subjects, with no known history of kidney stones.
Lean non-stone forming subjects: Adult subjects, gender-matched, and age-matched (within 10 years), to IUAN subjects, with BMI < 25 kg/m2 and no history of kidney stones.
Aim 2: Participants will be adult subjects with IUAN, age > 21 years of either sex, of any ethnicity. Some of the IUAN subjects from Aim 1b will be recruited and enrolled into this aim.