Hyperammonaemic encephalopathy due to non-functioning urea cycle as a complication to gastric bypass surgery

Kristoffer Kjærgaard; Peter Lykke  Eriksen; Thomas Kromann Nøhr; Steen Bønløkke Pedersen; Claus Højbjerg Gravholt; Hendrik V Arenstorff Vilstrup; Karen Louise Thomsen

doi:10.1007/s11011-024-01434-4

Hyperammonaemic encephalopathy due to non-functioning urea cycle as a complication to gastric bypass surgery

Kristoffer Kjærgaard^*, Peter Lykke Eriksen, Thomas Kromann Nøhr, Steen Bønløkke Pedersen, Claus Højbjerg Gravholt, Hendrik V Arenstorff Vilstrup, Karen Louise Thomsen

^*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

Abstract

Hyperammonaemic encephalopathy in the absence of liver failure is a major diagnostic challenge. A rare cause is as a complication to previous gastric bypass surgery, a condition reported to be associated with high mortality. In this case report, we present the exhaustive diagnostic work-up and clinical reversal of deep and recurrent hyperammonaemic encephalopathy in a patient with previous gastric bypass surgery. As a key finding, the patient exhibited an extreme reduction of the in vivo capacity for urea synthesis, which was reverted by long-standing correction of severe protein and micronutrient malnourishment (Functional Hepatic Nitrogen Clearance; 2.9 to 25.5 L/h). In addition, we observed reduced levels of fasting plasma amino acids (α-amino nitrogen; 2.7 to 3.6 mmol/L) and glucagon (0.3 to 2.6 pmol/L) before clinical improvement, which may contribute to the non-functioning urea synthesis. These observations elucidate the underlying pathophysiology of hyperammonaemia as a complication of gastric bypass and highlight a potential mechanism – non-functioning urea cycle as a result of protein malnourishment and hepatic glucagon resistance.

Original language	English
Article number	46
Journal	Metabolic Brain Disease
Volume	40
Issue	1
ISSN	0885-7490
DOIs	https://doi.org/10.1007/s11011-024-01434-4
Publication status	Published - Jan 2025

Keywords

Encephalopathy
Gastric bypass
Hyperammonaemia
Urea cycle dysfunction

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10.1007/s11011-024-01434-4Licence: CC BY

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title = "Hyperammonaemic encephalopathy due to non-functioning urea cycle as a complication to gastric bypass surgery",

abstract = "Hyperammonaemic encephalopathy in the absence of liver failure is a major diagnostic challenge. A rare cause is as a complication to previous gastric bypass surgery, a condition reported to be associated with high mortality. In this case report, we present the exhaustive diagnostic work-up and clinical reversal of deep and recurrent hyperammonaemic encephalopathy in a patient with previous gastric bypass surgery. As a key finding, the patient exhibited an extreme reduction of the in vivo capacity for urea synthesis, which was reverted by long-standing correction of severe protein and micronutrient malnourishment (Functional Hepatic Nitrogen Clearance; 2.9 to 25.5 L/h). In addition, we observed reduced levels of fasting plasma amino acids (α-amino nitrogen; 2.7 to 3.6 mmol/L) and glucagon (0.3 to 2.6 pmol/L) before clinical improvement, which may contribute to the non-functioning urea synthesis. These observations elucidate the underlying pathophysiology of hyperammonaemia as a complication of gastric bypass and highlight a potential mechanism – non-functioning urea cycle as a result of protein malnourishment and hepatic glucagon resistance.",

keywords = "Encephalopathy, Gastric bypass, Hyperammonaemia, Urea cycle dysfunction",

author = "Kristoffer Kj{\ae}rgaard and Eriksen, {Peter Lykke} and N{\o}hr, {Thomas Kromann} and Pedersen, {Steen B{\o}nl{\o}kke} and Gravholt, {Claus H{\o}jbjerg} and Vilstrup, {Hendrik V Arenstorff} and Thomsen, {Karen Louise}",

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doi = "10.1007/s11011-024-01434-4",

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Hyperammonaemic encephalopathy due to non-functioning urea cycle as a complication to gastric bypass surgery. / Kjærgaard, Kristoffer ; Eriksen, Peter Lykke ; Nøhr, Thomas Kromann et al.
In: Metabolic Brain Disease, Vol. 40, No. 1, 46, 01.2025.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

TY - JOUR

T1 - Hyperammonaemic encephalopathy due to non-functioning urea cycle as a complication to gastric bypass surgery

AU - Kjærgaard, Kristoffer

AU - Eriksen, Peter Lykke

AU - Nøhr, Thomas Kromann

AU - Pedersen, Steen Bønløkke

AU - Gravholt, Claus Højbjerg

AU - Vilstrup, Hendrik V Arenstorff

AU - Thomsen, Karen Louise

N1 - Publisher Copyright: © The Author(s) 2024.

PY - 2025/1

Y1 - 2025/1

N2 - Hyperammonaemic encephalopathy in the absence of liver failure is a major diagnostic challenge. A rare cause is as a complication to previous gastric bypass surgery, a condition reported to be associated with high mortality. In this case report, we present the exhaustive diagnostic work-up and clinical reversal of deep and recurrent hyperammonaemic encephalopathy in a patient with previous gastric bypass surgery. As a key finding, the patient exhibited an extreme reduction of the in vivo capacity for urea synthesis, which was reverted by long-standing correction of severe protein and micronutrient malnourishment (Functional Hepatic Nitrogen Clearance; 2.9 to 25.5 L/h). In addition, we observed reduced levels of fasting plasma amino acids (α-amino nitrogen; 2.7 to 3.6 mmol/L) and glucagon (0.3 to 2.6 pmol/L) before clinical improvement, which may contribute to the non-functioning urea synthesis. These observations elucidate the underlying pathophysiology of hyperammonaemia as a complication of gastric bypass and highlight a potential mechanism – non-functioning urea cycle as a result of protein malnourishment and hepatic glucagon resistance.

AB - Hyperammonaemic encephalopathy in the absence of liver failure is a major diagnostic challenge. A rare cause is as a complication to previous gastric bypass surgery, a condition reported to be associated with high mortality. In this case report, we present the exhaustive diagnostic work-up and clinical reversal of deep and recurrent hyperammonaemic encephalopathy in a patient with previous gastric bypass surgery. As a key finding, the patient exhibited an extreme reduction of the in vivo capacity for urea synthesis, which was reverted by long-standing correction of severe protein and micronutrient malnourishment (Functional Hepatic Nitrogen Clearance; 2.9 to 25.5 L/h). In addition, we observed reduced levels of fasting plasma amino acids (α-amino nitrogen; 2.7 to 3.6 mmol/L) and glucagon (0.3 to 2.6 pmol/L) before clinical improvement, which may contribute to the non-functioning urea synthesis. These observations elucidate the underlying pathophysiology of hyperammonaemia as a complication of gastric bypass and highlight a potential mechanism – non-functioning urea cycle as a result of protein malnourishment and hepatic glucagon resistance.

KW - Encephalopathy

KW - Gastric bypass

KW - Hyperammonaemia

KW - Urea cycle dysfunction

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JO - Metabolic Brain Disease

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ER -

Hyperammonaemic encephalopathy due to non-functioning urea cycle as a complication to gastric bypass surgery

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