The presence of an ammonia-like odor on the breath, often described as urinous or "fishy," is commonly observed in individuals with end-stage chronic kidney disease (CKD). This symptom tends to improve slightly following hemodialysis but remains a persistent issue throughout the progression of the disease. Though not immediately alarming, this breath odor is linked to significant metabolic disruptions caused by uremia and the breakdown of urea into ammonia in the saliva. Animal studies have identified toxic metabolites, including dimethylamine and trimethylamine, which are likely responsible for the characteristic "fishy" odor. These compounds may be generated by intestinal bacteria acting on dietary chlorine, though their precise source remains unclear.

Underlying Medical Causes

End-Stage Chronic Kidney Disease: The ammonia odor becomes evident in the later stages of CKD. It is accompanied by a range of symptoms, including anuria, changes in skin pigmentation, tissue breakdown, Kussmaul’s breathing patterns, neuropathy, fatigue, and cognitive confusion. Cardiovascular issues such as hypertension, heart failure, and stroke may also arise. Gastrointestinal disturbances are common, including anorexia, nausea, vomiting, and a metallic taste. Additionally, uremic frost, itching, and hormonal changes, such as sexual dysfunction or menstrual irregularities, can occur.

Special Considerations

While the ammonia breath odor may be bothersome to others, the patient may become desensitized to it over time. It's essential to emphasize the importance of regular oral hygiene to minimize this symptom. If the patient is unable to care for their oral hygiene, family members should be educated on how to assist with mouth care. Additionally, encouraging the patient to eat small, frequent meals tailored to their preferences (while adhering to dietary guidelines) can help support their nutritional intake.

Counseling for Patients. Patients should be encouraged to maintain consistent oral hygiene, particularly before meals, as it may help reduce the unpleasant taste and odor, potentially improving appetite. A gargle made from half-strength hydrogen peroxide and lemon juice may help neutralize the ammonia. The use of lozenges, breath sprays, or sucking on hard candies can further help freshen the breath. Patients should also use a soft toothbrush or sponge to avoid damaging oral tissues. Providing clear education about the cause of the ammonia odor once a diagnosis is made is crucial.

Pediatric Considerations. Ammonia-scented breath can also be observed in children with end-stage CKD. Offering hard candies can help relieve the bad taste and odor. For children who can gargle, a mixture of hydrogen peroxide and flavored mouthwash can be used to address the issue.

References

• Kreuzer, P., Langguth, B., Popp, R., Raster, R., Busch, V., Frank, E., … Landgrebe, M. (2011). Reduced intra-cortical inhibition after sleep deprivation: A transcranial magnetic stimulation study. Neuroscience Letter, 493(3), 63–66.

• Lo, J. C., Groeger, J. A., Santhi, N., Arbon, E. L., Lazar, A. S., Hasan, S., … Dijk, D. J. (2012). Effects of partial and acute total sleep deprivation on performance across cognitive domains, individuals, and circadian phase. PLOS ONE, 7(9), e45987.