Higher serum bicarbonate levels within the normal range are associated with better survival and renal outcomes in African Americans

Kidney Int. 2011 Feb;79(3):356-62. doi: 10.1038/ki.2010.388. Epub 2010 Oct 20.

Abstract

Recent studies suggest that correcting low serum bicarbonate levels may reduce the progression of kidney disease; however, few patients with chronic kidney disease have low serum bicarbonate. Therefore, we examined whether higher levels of serum bicarbonate within the normal range (20-30 mmol/l) were associated with better kidney outcomes in the African American Study of Kidney Disease and Hypertension (AASK) trial. At baseline and during follow-up of 1094 patients, the glomerular filtration rates (GFR) were measured by iothalamate clearances and events were adjudicated by the outcomes committee. Mean baseline serum bicarbonate, measured GFR, and proteinuria were 25.1 mmol/l, 46 ml/min per 1.73 m(2), and 326 mg/g of creatinine, respectively. Each 1 mmol/l increase in serum bicarbonate within the normal range was associated with reduced risk of death, dialysis, or GFR event and with dialysis or GFR event (hazard ratios of 0.942 and 0.932, respectively) in separate multivariable Cox regression models that included errors-in-variables calibration. Cubic spline regression showed that the lowest risk of GFR event or dialysis was found at serum bicarbonate levels near 28-30 mmol/l. Thus, our study suggests that serum bicarbonate is an independent predictor of CKD progression. Whether increasing serum bicarbonate into the high-normal range will improve kidney outcomes during interventional studies will need to be considered.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • African Americans / statistics & numerical data*
  • Aged
  • Antihypertensive Agents / therapeutic use*
  • Bicarbonates / blood*
  • Biomarkers / blood
  • Chronic Disease
  • Disease Progression
  • Female
  • Glomerular Filtration Rate
  • Humans
  • Hypertension / blood
  • Hypertension / drug therapy*
  • Hypertension / ethnology
  • Hypertension / mortality
  • Hypertension / physiopathology
  • Kidney Diseases / blood
  • Kidney Diseases / ethnology
  • Kidney Diseases / mortality
  • Kidney Diseases / physiopathology
  • Kidney Diseases / prevention & control*
  • Male
  • Middle Aged
  • Proportional Hazards Models
  • Proteinuria / blood
  • Proteinuria / ethnology
  • Proteinuria / mortality
  • Risk Assessment
  • Risk Factors
  • Survival Analysis
  • Survival Rate
  • Time Factors
  • Treatment Outcome
  • Up-Regulation

Substances

  • Antihypertensive Agents
  • Bicarbonates
  • Biomarkers