Trends in mineral metabolism: Kidney Early Evaluation Program (KEEP) and the National Health and Nutrition Examination Survey (NHANES) 1999-2004.
BACKGROUND
Chronic kidney disease (CKD) is associated with mineral metabolism dysregulation, cardiovascular disease, and premature mortality. No study specifically examined mineral metabolism trends in a generalizable sample of patients at increased CKD risk.


METHODS
This cross-sectional analysis from November 1, 2005, to December 31, 2006, of calcium, phosphorus, and parathyroid hormone (PTH) includes 2,646 individuals with estimated glomerular filtration rate (eGFR) less than 60 mL/min/1.73 m(2) in the National Kidney Foundation Kidney Early Evaluation Program (KEEP), a community-based health-screening program targeting individuals 18 years and older with diabetes, hypertension, or family history of kidney disease, diabetes, or hypertension. A parallel analysis of National Health and Nutrition Examination Survey (NHANES) 1999-2004 data was performed.


RESULTS
In KEEP, as eGFR decreased from 55 to less than 60 mL/min/1.73 m(2) to less than 30 mL/min/1.73 m(2), calcium level decreased (9.55 +/- 0.47 to 9.34 +/- 0.62 mg/dL; P < 0.001), phosphorus level increased (3.70 +/- 0.59 to 4.15 +/- 0.80 mg/dL; P < 0.001), and PTH level increased (66.3 +/- 36.3 to 164 +/- 109 pg/mL; mean, 80.8 +/- 57.0 pg/mL; P < 0.001). NHANES 1999-2004 showed similar trends, with PTH values not as high. Individuals within opinion-based Kidney Disease Outcomes Quality Initiatives targets from the highest to the lowest eGFR group were as follows: calcium, 93.0% to 92.3% (KEEP) and 97.4% to 89.6% (NHANES); phosphorus, 90.4% to 90.3% (KEEP) and 91.6% to 87.1% (NHANES); and PTH, 46.1% to 31.2% (KEEP) and 56.4% to 36.1% (NHANES).


CONCLUSIONS
In a community-based CKD screening population, increased PTH level occurs early in patients with stage 3, typically with normal calcium and phosphorus levels. These findings support the importance of including PTH with calcium and phosphorus monitoring for individuals with eGFR less than 60 mL/min/1.73 m(2).
Vassalotti
Joseph A
JA
National Kidney Foundation, Mount Sinai School of Medicine, One Gustave L. Levy Pl, Nephrology Box 1243, New York, NY 10029-6574, USA. joseph.vassalotti@mssm.edu
Uribarri
Jaime
J
Chen
Shu-Cheng
SC
Li
Suying
S
Wang
Changchun
C
Collins
Allan J
AJ
Calvo
Mona S
MS
Whaley-Connell
Adam T
AT
McCullough
Peter A
PA
Norris
Keith C
KC
D000293:Adolescent; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002908:Chronic Disease; D003153:Community Health Services / Q000379:methods / Q000639:trends; D003430:Cross-Sectional Studies; D016208:Databases, Factual / Q000639:trends; D042241:Early Diagnosis; D005260:Female; D005582:Foundations / Q000639:trends; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D007674:Kidney Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000378:metabolism*; D008297:Male; D008403:Mass Screening / Q000379:methods / Q000639:trends*; D008875:Middle Aged; D009749:Nutrition Surveys; D010281:Parathyroid Hormone / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D012307:Risk Factors; D014481:United States / Q000453:epidemiology
D015415:Biomarkers; C470125:PTH protein, human; D010281:Parathyroid Hormone; D010758:Phosphorus; D002118:Calcium