Increasing Blood Flow Will Not Eliminate Bitter Taste in Dialysis Patients
No, increasing blood flow during dialysis will not eliminate the bitter taste experienced by patients, as dysgeusia (abnormal taste perception) in dialysis patients is a neurological manifestation of uremic neuropathy and metabolic derangements, not a function of dialysis adequacy or blood flow rate. 1, 2
Understanding the Mechanism of Taste Alterations
The bitter taste and other taste abnormalities in dialysis patients result from:
Uremic neuropathy affecting taste perception: Impaired cognitive taste recognition occurs across all taste modalities (sweet, salty, sour, bitter) in both dialyzed and non-dialyzed uremic patients, representing a subtle neurological complication of uremia itself 2
Metabolic accumulation of tastants: Elevated serum levels of compounds like potassium, urea, and other uremic toxins correlate with altered taste perceptions, with some patients experiencing paradoxically more intense taste sensations for certain compounds (particularly monosodium glutamate, sodium chloride, and sodium phosphate) when adjusted for baseline taste abnormalities 1
Persistent impairment despite dialysis: No significant differences in taste recognition exist between dialyzed and non-dialyzed uremic patients, indicating that standard dialysis does not correct the underlying taste dysfunction 2
Evidence Against Blood Flow as a Solution
Increasing blood flow rate improves dialysis adequacy (Kt/V) but does not address taste abnormalities:
Blood flow increases from 200 to 400 mL/min successfully augment Kt/V in patients with both normal and compromised vascular access, even when minor access recirculation occurs 3
However, taste acuity remains impaired in hemodialysis patients regardless of dialysis adequacy, with detection thresholds for bitter and salty tastes significantly elevated compared to healthy controls 4
Temporal Pattern of Taste Changes
Limited and transient improvement occurs immediately post-dialysis, but this is unrelated to blood flow rate:
Some younger dialysis patients (<55 years) show modest improvement in recognition of "sour" and "bitter" tastes when tested immediately after dialysis sessions compared to pre-dialysis 2
This temporary improvement likely reflects acute removal of specific uremic toxins rather than any blood flow-dependent mechanism 2
Previous sensory work demonstrates taste improves after dialysis sessions, but this effect is time-dependent (related to toxin removal) rather than flow-dependent 1
Clinical Pitfalls to Avoid
Do not attempt to address dysgeusia by manipulating dialysis blood flow parameters:
Increasing blood flow beyond what is needed for adequate Kt/V provides no additional benefit for taste symptoms and may increase vascular access complications 3
The focus should be on achieving adequate dialysis adequacy (Kt/V) through appropriate blood flow rates (typically 300-400 mL/min), but recognize this will not resolve taste complaints 3
Taste abnormalities persist in CAPD patients (who have continuous dialysis without blood flow considerations), confirming that dialysis modality and flow dynamics are not the primary determinants 4, 5
Age-Related Considerations
Younger uremic patients (<55 years) demonstrate more pronounced taste impairment across all modalities compared to older patients, suggesting age may modulate the severity of uremic neuropathy affecting taste 2. However, neither age group benefits from blood flow manipulation for taste symptoms 2.
What Actually Matters for Taste
The evidence indicates that taste dysfunction in dialysis patients represents a complex interplay of uremic neuropathy and circulating tastant compounds that is not corrected by optimizing dialysis blood flow rates 1, 2. Zinc deficiency has been excluded as a causative factor in these patients 2.