Hyperammonemia: Difference between revisions
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==Background== | ==Background== | ||
===Pathophysiology=== | ===Pathophysiology=== | ||
*Acquired: liver failure results in shunting of blood from the liver to the inferior vena cava, decreased filtration of blood and removal of nitrogen-containing toxins by the liver, and then hyperammonemia. | *Acquired: liver failure results in shunting of blood from the liver to the inferior vena cava, decreased filtration of blood and removal of nitrogen-containing toxins by the liver, and then hyperammonemia. | ||
*Congenital: Defect in one of the enzymes of the urea cycle, which leads to lower production of urea from ammonia. | *Congenital: Defect in one of the enzymes of the urea cycle, which leads to lower production of urea from ammonia. | ||
===Types=== | ===Types=== | ||
*Primary | *Primary | ||
**Caused by several [[inborn errors of metabolism]] | **Caused by several [[Special:MyLanguage/inborn errors of metabolism|inborn errors of metabolism]] | ||
**Characterized by reduced activity of urea cycle enzymes | **Characterized by reduced activity of urea cycle enzymes | ||
*Secondary | *Secondary | ||
**Caused by inborn errors of intermediary metabolism (i.e. reduced activity of enzymes that are not part of the urea cycle) | **Caused by inborn errors of intermediary metabolism (i.e. reduced activity of enzymes that are not part of the urea cycle) | ||
**Typically from acute or chronic [[liver failure]] | **Typically from acute or chronic [[Special:MyLanguage/liver failure|liver failure]] | ||
==Clinical Features== | ==Clinical Features== | ||
*[[AMS]]- ranging from mild apathy to frank coma | |||
*[[Special:MyLanguage/AMS|AMS]]- ranging from mild apathy to frank coma | |||
* +/- asterexis | * +/- asterexis | ||
*Signs/symptoms of underlying disease or trigger for exacerbation | *Signs/symptoms of underlying disease or trigger for exacerbation | ||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
===Elevated ammonia level<ref>Ferenci, P. Hepatic encephalopathy in adults: Clinical manifestations and diagnosis. In: UpToDate, Post, TW (Ed), UpToDate, Waltham, MA, 2020</ref>=== | ===Elevated ammonia level<ref>Ferenci, P. Hepatic encephalopathy in adults: Clinical manifestations and diagnosis. In: UpToDate, Post, TW (Ed), UpToDate, Waltham, MA, 2020</ref>=== | ||
*[[Liver failure]] | |||
*[[Inborn errors of metabolism]] with urea cycle defects and organic acidemia | *[[Special:MyLanguage/Liver failure|Liver failure]] | ||
*[[Shock]], severe [[dehydration]] | *[[Special:MyLanguage/Inborn errors of metabolism|Inborn errors of metabolism]] with urea cycle defects and organic acidemia | ||
*[[Renal failure]] | *[[Special:MyLanguage/Shock|Shock]], severe [[Special:MyLanguage/dehydration|dehydration]] | ||
*[[Gastrointestinal bleeding]] | *[[Special:MyLanguage/Renal failure|Renal failure]] | ||
*[[Urinary tract infection]] with a urease-producing organism (i.e. [[proteus mirabilis]]), systemic infection with [[mycoplasma]] hominis or ureasplasma species in [[lung transplant]] patients | *[[Special:MyLanguage/Gastrointestinal bleeding|Gastrointestinal bleeding]] | ||
*[[Reye syndrome]] | *[[Special:MyLanguage/Urinary tract infection|Urinary tract infection]] with a urease-producing organism (i.e. [[Special:MyLanguage/proteus mirabilis|proteus mirabilis]]), systemic infection with [[Special:MyLanguage/mycoplasma|mycoplasma]] hominis or ureasplasma species in [[Special:MyLanguage/lung transplant|lung transplant]] patients | ||
*[[Special:MyLanguage/Reye syndrome|Reye syndrome]] | |||
*Any cause of portosystemic shunting of blood | *Any cause of portosystemic shunting of blood | ||
*Ureterosigmoidostomy | *Ureterosigmoidostomy | ||
| Line 33: | Line 47: | ||
*Medication toxicity, including: | *Medication toxicity, including: | ||
**High dose chemotherapy | **High dose chemotherapy | ||
**[[valproate OD|Valproic acid]] | **[[Special:MyLanguage/valproate OD|Valproic acid]] | ||
**[[Barbiturate toxicity|Barbiturates]] | **[[Special:MyLanguage/Barbiturate toxicity|Barbiturates]] | ||
**[[ETOH intoxication]]|ETOH]] | **[[Special:MyLanguage/ETOH intoxication|ETOH intoxication]]|ETOH]] | ||
**[[Diuretics]] | **[[Special:MyLanguage/Diuretics|Diuretics]] | ||
**[[Salicylate toxicity|ASA]] | **[[Special:MyLanguage/Salicylate toxicity|ASA]] | ||
**Glycine toxicity | **Glycine toxicity | ||
</translate> | |||
{{Template:AMS DDX}} | {{Template:AMS DDX}} | ||
<translate> | |||
==Evaluation== | ==Evaluation== | ||
*Evaluate for suspected underlying etiology as above and/or alternate etiology of presenting symptoms (e.g. workup for other causes of [[AMS]]) | |||
*Evaluate for suspected underlying etiology as above and/or alternate etiology of presenting symptoms (e.g. workup for other causes of [[Special:MyLanguage/AMS|AMS]]) | |||
*Normal range of ammonia in adult is typically 10-80 mcg/dL or 6-47 μmol/L, <100 in neonate, HOWEVER severity of hepatic encephalopathy is inconsistently correlated to severity of ammonia elevation<ref>Ong JP, Aggarwal A, Krieger D, Easley KA, Karafa MT, Van Lente F, Arroliga AC, Mullen KD. Correlation between ammonia levels and the severity of hepatic encephalopathy. Am J Med. 2003 Feb 15;114(3):188-93. doi: 10.1016/s0002-9343(02)01477-8. PMID: 12637132.</ref> | *Normal range of ammonia in adult is typically 10-80 mcg/dL or 6-47 μmol/L, <100 in neonate, HOWEVER severity of hepatic encephalopathy is inconsistently correlated to severity of ammonia elevation<ref>Ong JP, Aggarwal A, Krieger D, Easley KA, Karafa MT, Van Lente F, Arroliga AC, Mullen KD. Correlation between ammonia levels and the severity of hepatic encephalopathy. Am J Med. 2003 Feb 15;114(3):188-93. doi: 10.1016/s0002-9343(02)01477-8. PMID: 12637132.</ref> | ||
**Value of ammonia level in liver disease more helpful to trend rather than as absolute number | **Value of ammonia level in liver disease more helpful to trend rather than as absolute number | ||
==Management== | ==Management== | ||
*Treat underlying disorder | *Treat underlying disorder | ||
*If [[hepatic encephalopathy]]: | *If [[Special:MyLanguage/hepatic encephalopathy|hepatic encephalopathy]]: | ||
**[[Lactulose]] 20g PO or (300mL in 700cc H2O retention enema x30min) | **[[Special:MyLanguage/Lactulose|Lactulose]] 20g PO or (300mL in 700cc H2O retention enema x30min) | ||
***In colon degrades into lactic acid: acidic environment traps ammonia | ***In colon degrades into lactic acid: acidic environment traps ammonia | ||
***Also inhibits ammonia production in gut wall | ***Also inhibits ammonia production in gut wall | ||
*If secondary to inborn error of metabolism | *If secondary to inborn error of metabolism | ||
**[[sodium phenylacetate/sodium benzoate]] (Ammonul) 250mg/kg in D10 over 90min; then 250mg/kg/d infusion | **[[Special:MyLanguage/sodium phenylacetate/sodium benzoate|sodium phenylacetate/sodium benzoate]] (Ammonul) 250mg/kg in D10 over 90min; then 250mg/kg/d infusion | ||
**Arginine 210mg/kg IV/IO in D10 over 90min; then 210mg/kg/d infusion | **Arginine 210mg/kg IV/IO in D10 over 90min; then 210mg/kg/d infusion | ||
**+/- [[levocarnitine|carnitine]], 400 mg IV/IO in consultation w/specialist | **+/- [[Special:MyLanguage/levocarnitine|carnitine]], 400 mg IV/IO in consultation w/specialist | ||
**May require [[dialysis]] if refractory/severe | **May require [[Special:MyLanguage/dialysis|dialysis]] if refractory/severe | ||
==Disposition== | ==Disposition== | ||
*Depends on cause | *Depends on cause | ||
==See Also== | ==See Also== | ||
*[[Inborn errors of metabolism]] | |||
*[[Hepatic encephalopathy]] | *[[Special:MyLanguage/Inborn errors of metabolism|Inborn errors of metabolism]] | ||
*[[Special:MyLanguage/Hepatic encephalopathy|Hepatic encephalopathy]] | |||
==External Links== | ==External Links== | ||
| Line 70: | Line 95: | ||
==References== | ==References== | ||
<references/> | <references/> | ||
[[Category:GI]] | [[Category:GI]] | ||
</translate> | |||
Latest revision as of 23:08, 4 January 2026
Background
Pathophysiology
- Acquired: liver failure results in shunting of blood from the liver to the inferior vena cava, decreased filtration of blood and removal of nitrogen-containing toxins by the liver, and then hyperammonemia.
- Congenital: Defect in one of the enzymes of the urea cycle, which leads to lower production of urea from ammonia.
Types
- Primary
- Caused by several inborn errors of metabolism
- Characterized by reduced activity of urea cycle enzymes
- Secondary
- Caused by inborn errors of intermediary metabolism (i.e. reduced activity of enzymes that are not part of the urea cycle)
- Typically from acute or chronic liver failure
Clinical Features
- AMS- ranging from mild apathy to frank coma
- +/- asterexis
- Signs/symptoms of underlying disease or trigger for exacerbation
Differential Diagnosis
Elevated ammonia level[1]
- Liver failure
- Inborn errors of metabolism with urea cycle defects and organic acidemia
- Shock, severe dehydration
- Renal failure
- Gastrointestinal bleeding
- Urinary tract infection with a urease-producing organism (i.e. proteus mirabilis), systemic infection with mycoplasma hominis or ureasplasma species in lung transplant patients
- Reye syndrome
- Any cause of portosystemic shunting of blood
- Ureterosigmoidostomy
- Cigarette smoking
- Transient hyperammonemia in newborns
- Parenteral nutrition
- Medication toxicity, including:
- High dose chemotherapy
- Valproic acid
- Barbiturates
- ETOH intoxication|ETOH]]
- Diuretics
- ASA
- Glycine toxicity
Altered mental status
Diffuse brain dysfunction
- Hypoxic encephalopathy
- Acute toxic-metabolic encephalopathy (Delirium)
- Hypoglycemia
- Hyperosmolar state (e.g., hyperglycemia)
- Electrolyte Abnormalities (hypernatremia or hyponatremia, hypercalcemia)
- Organ system failure
- Hepatic Encephalopathy
- Uremia/Renal Failure
- Endocrine (Addison's disease, Cushing syndrome, hypothyroidism, myxedema coma, thyroid storm)
- Hypoxia
- CO2 narcosis
- Hypertensive Encephalopathy
- Toxins
- TTP / Thrombotic thrombocytopenic purpura
- Alcohol withdrawal
- Drug reactions (NMS, Serotonin Syndrome)
- Environmental causes
- Deficiency state
- Wernicke encephalopathy
- Subacute Combined Degeneration of Spinal Cord (B12 deficiency)
- Vitamin D Deficiency
- Zinc Deficiency
- Sepsis
- Osmotic demyelination syndrome (central pontine myelinolysis)
- Limbic encephalitis
Primary CNS disease or trauma
- Direct CNS trauma
- Diffuse axonal injury
- Subdural/epidural hematoma
- Vascular disease
- SAH
- Stroke
- Hemispheric, brainstem
- CNS infections
- Neoplasms
- Paraneoplastic Limbic encephalitis
- Malignant Meningitis
- Pancreatic Insulinoma
- Seizures
- Nonconvulsive status epilepticus
- Postictal state
- Dementia
Psychiatric
Evaluation
- Evaluate for suspected underlying etiology as above and/or alternate etiology of presenting symptoms (e.g. workup for other causes of AMS)
- Normal range of ammonia in adult is typically 10-80 mcg/dL or 6-47 μmol/L, <100 in neonate, HOWEVER severity of hepatic encephalopathy is inconsistently correlated to severity of ammonia elevation[2]
- Value of ammonia level in liver disease more helpful to trend rather than as absolute number
Management
- Treat underlying disorder
- If hepatic encephalopathy:
- Lactulose 20g PO or (300mL in 700cc H2O retention enema x30min)
- In colon degrades into lactic acid: acidic environment traps ammonia
- Also inhibits ammonia production in gut wall
- Lactulose 20g PO or (300mL in 700cc H2O retention enema x30min)
- If secondary to inborn error of metabolism
- sodium phenylacetate/sodium benzoate (Ammonul) 250mg/kg in D10 over 90min; then 250mg/kg/d infusion
- Arginine 210mg/kg IV/IO in D10 over 90min; then 210mg/kg/d infusion
- +/- carnitine, 400 mg IV/IO in consultation w/specialist
- May require dialysis if refractory/severe
Disposition
- Depends on cause
See Also
External Links
References
- ↑ Ferenci, P. Hepatic encephalopathy in adults: Clinical manifestations and diagnosis. In: UpToDate, Post, TW (Ed), UpToDate, Waltham, MA, 2020
- ↑ Ong JP, Aggarwal A, Krieger D, Easley KA, Karafa MT, Van Lente F, Arroliga AC, Mullen KD. Correlation between ammonia levels and the severity of hepatic encephalopathy. Am J Med. 2003 Feb 15;114(3):188-93. doi: 10.1016/s0002-9343(02)01477-8. PMID: 12637132.