Trends in Mineral Metabolism: Kidney Early Evaluation Program (KEEP) and the National Health and Nutrition Examination Survey (NHANES) 1999-2004
Received 16 November 2007; accepted 31 December 2007.
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 m2 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 m2 to less than 30 mL/min/1.73 m2, 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 m2.
2Department of Medicine, Division of Nephrology, Mount Sinai School of Medicine, New York, NY
3Chronic Disease Research Group, Minneapolis Medical Research Foundation, Minneapolis, MN
4Department of Medicine, University of Minnesota, Minneapolis, MN
5Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, US Food and Drug Administration, Laurel, MD
6Department of Medicine, Division of Nephrology, University of Missouri-Columbia School of Medicine, Columbia, MO
7Department of Medicine, Divisions of Cardiology, Nutrition, and Preventive Medicine, William Beaumont Hospital, Royal Oak, MI
8Charles R. Drew University of Medicine and Science, Los Angeles, CA
9David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA.
Address correspondence to Joseph A. Vassalotti, MD, Chief Medical Officer, National Kidney Foundation, Mount Sinai School of Medicine, One Gustave L. Levy Pl, Nephrology Box 1243, New York, NY 10029-6574.
A list of the members of the Kidney Early Evaluation Program Investigators appears at the end of this article.
ABSTRACT