Hemoglobin Drop After Dialysis

Blood Loss and Hemodilution

Modern dialysis membranes cause blood loss of only 0.3-0.9 mL per session, with blood-line losses adding another 0.2 mL, totaling approximately 1.1 mL per session, according to the National Kidney Foundation 1, 2, 3
Annual blood loss from the dialysis technique itself is only 165 mL per year, which translates to barely over 1 mL per session, as reported by the American Society of Nephrology 1, 2
Double-lumen catheters cause 2.7 L of blood loss annually due to purge protocols that discard 7-10 mL of blood from each catheter branch at each session, as stated by the Centers for Disease Control and Prevention 1, 2, 3
For a first dialysis session with a catheter, this would represent approximately 14-20 mL of blood loss from the purge alone, still insufficient to cause a 2 g/dL hemoglobin drop, according to the National Institute of Diabetes and Digestive and Kidney Diseases 2

Laboratory error or sampling technique issues, such as dilution of the pre-dialysis sample with saline, or drawing the post-dialysis sample before adequate time has elapsed for equilibration, can cause a 2 g/dL hemoglobin drop, as noted by the American Journal of Kidney Diseases 4, 5, 6
Occult bleeding, such as uremic enteropathy, causes occult gastrointestinal bleeding averaging 2,257 mL per year in chronic dialysis patients, and should be considered as a possible cause, as reported by the European Renal Association 1, 2

For a 2 g/dL hemoglobin drop after first dialysis, repeat the hemoglobin measurement using proper sampling technique, as recommended by the American Society of Nephrology 6
Review the dialysis record for excessive blood loss from the circuit, catheter purge volume, or equipment malfunction, as suggested by the Centers for Disease Control and Prevention 2