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Serum Phosphate (sPO4) is Lower in Older Kidney Transplant Recipients and Related to Low Phosphorous and Protein Intake and Not Urinary Losses
Author(s) -
Mincer Shifra,
Ruff Eric,
Markell Mariana
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.645.7
Subject(s) - medicine , creatinine , hypophosphatemia , dialysis , renal function , urinary system , kidney transplantation , kidney
Background Hypophosphatemia (LoPO4) is a persistent problem in long term (>1 year) kidney transplant recipients (KTR's) with good kidney function and may contribute to bone loss and other morbidities. The etiology is unclear, as hyperparathyroidism is common, and urine losses may play a role. Methods 23 randomly selected long term KTRs were recruited from the Transplant Clinic. Laboratory values were obtained from chart review and demographics from face to face interview. Dietary intake was estimated from 3‐day diet diary. Nutrient values were extrapolated using the USDA Supertracker. Results There were 18 (60%) men and 20 Black (67%) patients. 50% were American born, 17 (80%) reported income <$20,000 and Medicaid as primary Insurance. Mean age was 44.7±10.1 with 53% older than 45 years (>AGE), BMI 27.9±5.6, months since transplant 87.7±59.4, sPO4 2.79±0.7, creatinine 0.88±0.1 mg/dl. 67% of >AGE patients met the criteria for LoPO4 vs 10% of the younger patients. 12 pts returned the 3‐day diet history. By Mann‐Whitney U test >AGE pts had been on dialysis longer (106.8±10.2 vs 63.1±12.3, p<0.05), had lower sPO4 values (2.4±0.13 vs 3.1±0.2, p=0.007) and lower total protein intake (59±9.0 vs 90.2±7.8 g/d, p<0.05). PO4 intake was also lower (953.6±164.6 vs 1281.0±155.6) but was not significant (p=0.08). Although intact PTH was higher (235.8±45.8 vs 91.6±16.9, p<0.005), there was no difference in intake of sugars, fats, eGFR, urinary PO4 or fractional excretion of PO4. Conclusions In our population of indigent inner‐City KTR's 1). LoPO4 remained common and was more prevalent in the patients over 45 years of age. As LoPO4 may alter bone health this finding is especially worrisome in the older age group. 2) Older patients ate less protein and phosphate. 3) Although older patients had higher PTH values, urinary PO4 losses were minimal and were similar to younger patients suggesting that dietary intake was the biggest factor influencing sPO4. 4) Patients are taught to restrict PO4 while on dialysis, whether the longer dialysis time influenced older patient's food choices remains to be investigated.