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Abstract: PO0893

Metabolic Alkalosis in Hemodialysis Patients

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Mudunuru, Sitarama Arvind, Emory University School of Medicine, Atlanta, Georgia, United States
  • Navarrete, Jose E., Emory University School of Medicine, Atlanta, Georgia, United States
  • O'Neill, W. Charles, Emory University School of Medicine, Atlanta, Georgia, United States
Background

Hemodialysis (HD) typically employs a high dialysate alkali concentration to counteract interdialytic acid production. Since acid production varies due to the amount and type of protein consumed, some patients may remain alkalotic throughout the interdialytic period and be more alkalotic during HD. This could have adverse effects including arrhythmias, hypotension, hypoventilation, and vascular calcification but dialysate alkali is rarely adjusted. Pre-HD alkalosis is usually ascribed to chronic illness and poor nutrition, but this has not been carefully examined.

Methods

We conducted a retrospective case-control study of all in-center HD patients from 2010 - 2020 at 4 outpatient HD units using citrate-containing dialysate (34.6 meq/L HCO3, 0.4 meq/L acetate, 2.4 meq/L citrate; citrasate, Fresenius). Interdialytic alkalosis was defined as pre-HD serum [HCO3] >26 in > 7 months of any 12-month period. Persistent alkalosis was defined as interdialytic alkalosis in every subsequent 12-month period. Patients with serum [HCO3] 19-23 in > 7 months of every 12-month period constituted the control cohort.

Results

Of 1271 patients with at least 12 months of HD, 444 met the alkalosis criteria for at least one 12-month period and 73 had persistent alkalosis. 189 patients met the control criteria for every 12-month period. Patients with persistent alkalosis were older (66 vs 55 years, p<0.001) and weighed less (69 vs 82 kg, p= 0.003), but the prevalence of comorbidities including cardiovascular disease, neoplasia, and diabetes was not increased. HD dose (kT/V) was greater (1.47 vs 1.37, p<0.001), protein catabolic rate was lower (0.85 vs 0.96 g/kg/day, p <0.001), and interdialytic weight gain was less (1.62 vs 2.28 kg, p<0.001). Despite significant weight loss over time (7 + 13 vs. 0 + 9 kg, p <0.001), mortality was not increased when adjusted for age, serum albumin was only slightly lower (3.71 vs 3.80 g/dl, p=0.03), and other markers of malnutrition/chronic illness such as serum cholesterol and hemoglobin did not differ from control patients.

Conclusion

Transient interdialytic alkalosis was common in this HD population and persistent alkalosis was not rare (>5%). Alkalosis appeared to result from a greater dialysis dose and lower protein intake but not chronic illness. Further studies are needed to determine whether this alkalosis is detrimental and adjustment of dialysate [HCO3] is indicated.