Arteriovenous Difference of Blood Ammonia in Uremic Patients Under Hemodialysis

Abstract

In this study the ammonia concentration was determined in arterial and venous blood samples pre- and posthemodialysis (HD) in 18 uremic patients and in 18 health subjects (controls). The mean values (+/- SD) of ammonia in the arterial blood of uremic patients pre-HD were 98.32 +/- 26.55; post-HD, 63.18 +/- 17.09; and in control group patients, 72.37 +/- 10.09 micrograms/dl. In venous blood they were pre-HD, 71.70 +/- 20.68; post-HD, 58.05 +/- 16.73; and in control patients, 74.46 +/- 12.0 micrograms/dl. According to our findings, the ammonia concentration in the arterial blood of uremic patients pre-HD exceeds the normal limits and is significantly higher (p < 0.001) than that post-HD and that of control patients. The ammonia contents of venous blood pre- and post-HD ranges were within normal values, but the post-HD range was significantly lower than the pre-HD range (p < 0.05) and the control range (p < 0.01). Comparison between ammonia levels from arterial and venous blood showed significant and positive arteriovenous differences pre-HD (p < 0.001), which disappeared post-HD and were not observed in the control patients. In conclusion, uremic patients under HD present pre-HD high levels of ammonia in arterial blood with a significantly positive arteriovenous difference. In contrast, the post-HD ammonia levels in arterial and venous blood are decreased, and the arteriovenous difference is not significant.

Two Cases of Hemodialysis-associated Chronic Portal-systemic Shunt Encephalopathy (CPSE) with Opposite Changes in the Blood Ammonia Concentrations during Hemodialysis: A Case Report and Literature Review

“…In a previous study, the blood ammonia concentrations in hemodialysis patients without cirrhosis decreased after dialysis therapy (14). The same phenomenon was confirmed in the current case 1, whereas the blood ammonia concentration increased after hemodialysis therapy in case 2.…”

Determination of Arterial Blood Ammonia in Uremic Patients Before and After Hemodialysis Using Three Different Ammonia Methods

“…About one‐third of this ammonia is released in the precursor urine of the renal tubes and two‐thirds is released by the renal vein (8). In our study, in contrast to the results of Agroyannis and colleagues (1), the same ammonia values pre‐ and post‐hemodialysis using three independent methods were found. The choice of an ammonia method depends, among other things, on the available equipment and cost and the speed of a method, the latter particularly important with respect to sample handling.…”

“…With interest we have read the article of Agroyannis and colleagues (1) on the arteriovenous difference of blood ammonia in uremic patients treated with hemodialysis. In this study using arterial samples, blood ammonia values pre‐hemodialysis were significantly higher than in post‐hemodialysis samples.…”

Bioaccumulation of Blood Long-Chain Fatty Acids during Hemodialysis

“…Venous blood was withdrawn from upper limbs. In this case, measurement of FA consumption by the specific organ system requires the determination of the FA content of venous blood draining from that organ [ 20 , 21 , 22 , 23 ]. We applied this approach to better understand bioaccumulation and biotransformation of FAs in vivo, particularly whether or not the peripheral tissues, especially the muscles in the upper limbs, either produce, store, or degrade part of the FAs that pass through them in response to dialysis treatment.…”

“…This difference shows how much O 2 is removed from the blood in capillaries as the blood circulates in the body. ESRD patients present, before HD, with high ammonia plasma levels in arterial blood with a significantly positive arterio–venous difference [ 20 ]. The A–V blood glucose gradient is related to the fact that the peripheral tissues, especially the muscles, either store or burn part of the traversing glucose [ 21 ].…”