Normal Phosphate Levels May Predict CKD Progression

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This article is part of our ongoing coverage of Renal Week 2009. Click here for a complete list of our Renal Week Live articles.


Key Points

  • Serum phosphate within the normal range is a strong predictor of CKD progression.
  • Patients who had renal events had significantly higher serum phosphate levels than those who did not (4.2 vs. 3.7 mg/dL).
  • Each 1 mg/dL increment in phosphate level was associated with an 86% increased risk of a renal event.

Serum phosphate within the normal range is a strong predictor of CKD progression, according to Italian researchers who presented a study at ASN's Renal Week 2009.

Carmine Zoccali, MD, from Ospedali Riuniti, Reggio Calabria, Italy, and colleagues examined the association between serum phosphate and renal events (a greater than 30% decrease in estimated glomerular filtration rate [eGFR]) in a cohort of 549 CKD patients. The group had a mean eGFR of 29 mL/min/1.73 m2 at baseline.

During an average follow-up of 19 months, 115 renal events occurred. The patients who had renal events had significantly higher serum phosphate levels than those who did not (4.2 vs. 3.7 mg/dL), according to the investigators.

Univariate analysis showed phosphate levels to be a strong predictor of renal events. Each 1 mg/dL increment in phosphate level was associated with an 86% increased risk of a renal event. Adjusting for Framingham risk factors (age, gender, cholesterol, smoking, diabetes, arterial pressure) and BMI did not modify the predictive power of phosphate.

The relationship between phosphate and renal disease progression was not affected by adjustment for proteinuria, but it was attenuated after adjusting for baseline eGFR.

The researchers concluded that serum phosphate within the normal range is a strong predictor of renal disease progression, independent of Framingham risk factors, BMI, and proteinuria.

The observation that phosphate loses predictive power for CKD progression after adjusting for eGFR “indicates that this marker of renal function either confounds or mediates the effect of phosphate on renal disease progression,” noted investigators.

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