Post-transplant Phosphatemia: Duration and Pathogenesis
Hypothesis: 1. Renal transplant patients continue to have renal phosphorus wasting and negative phosphorus balance despite the normalization of serum phosphorus after renal transplantation. 2. Renal Pi wasting is partially due to elevated serum FGF23 and/or urinary prostaglandin E2 which decreases the renal proximal tubule Na-phosphate cotransporter NaPi-IIa, resulting in defective renal tubular Pi reabsorption and renal Pi wasting. We postulate that inhibition of synthesis of PGE2 can partially correct this defect. 3. Despite normal phosphorus blood levels, persistent renal Pi wasting contributes to the development of post-renal transplant osteodystrophy; in particular.
Aim 1a: **Aim 1a was closed to enrollment via a MOD submitted on 7/15/2010**
Aim 1b: **Aim 1b was closed to enrollment via a MOD submitted on 7/15/2010**
Aim 2: **Aim 2 was closed to enrollment via a MOD submitted on 7/15/2010**
Aim 3: **Aim 3 was closed to enrollment via a MOD submitted on 7/15/2010**
Aim 4: Aim 4 will try to establish the correlation between potential phosphaturic substances (FGF23), biochemical marker reflective of Pi wasting (TMP/GFR) by studying the patients on an out patient basis. The subject will collect a 24 hour urine and bring it to the outpatient CTRC. A single blood sample and a 2 hour fasting urine will be collected. Analyses: 24o urine: TV, Na, Cr, Ca, Pi,Mg, pH, DPD. 2 hour fasting urine: TV, Cr, Na, Ca, Pi, Mg, pH. Fasting blood: Standard of care – CBC, Chem 7, ionized calcium, Mg, Pi,PTH, 25-hydroxyvitaminD, and 1,25-dihydroxyvitaminD; Research – c-terminal telopeptide of type-1 collagen (CTX), bone specific alkaline phosphatase (BSAP), FGF-23, matrix extracellular phosphoglycoprotein (MEPE), frizzled related protein 4 (FRP4). 2.5 tablespoons of blood will be drawn for standard of care tests and 1.5 tablespoons will be drawn for research tests.
Criteria for Inclusion of Subjects:
Aim 1a: Aim 1a was closed to enrollment.
Aim 1b: Aim 1b was closed to enrollment
Aim 2: Aim 2 was closed to enrollment.
Aim 3: Aim 3 was closed to enrollment.
Aim 4: 100 Post renal transplant patients that have had a kidney transplant greater than 2 weeks of any gender or ethnicity between ages 21-60 years.