Tests
1st tests to order
liver function tests
Test
Result depends on presence and type of hepatic dysfunction.
Result
abnormal
serum glucose
Test
Serum glucose should be normal in patients with HE. Hypo- and hyperglycemia should be excluded because they are treatable causes of altered consciousness.
Result
normal
coagulation profile
Test
Result
elevated prothrombin time
serum electrolytes
Test
Hyponatremia is common in patients with cirrhosis. Hypokalemia can precipitate HE.
Result
normal or hyponatremia or hypokalemia
BUN and creatinine
Test
BUN is raised if there is a history of upper gastrointestinal bleeding. Patients with cirrhosis and renal impairment are at higher risk of HE.
Result
normal or elevated
arterial or venous blood gas
Test
Metabolic alkalosis may precipitate HE.
Result
normal or metabolic alkalosis
CBC
Test
Elevated white cell count and thrombocytosis may indicate infection.
Result
normal or leukocytosis or thrombocytosis
inflammatory markers (e.g., CRP)
Test
May indicate infection if elevated. Infections can be a precipitating cause of HE. They can also present with delirium, which can mimic HE.
Result
normal or elevated
thyroid-stimulating hormone
Test
Hypothyroidism can present with HE-like symptoms, and low T4 has been associated with development of grade 3-4 HE.[25]
Result
normal
blood alcohol level
Test
Alcohol intoxication can present with HE-like symptoms. Alcohol is also a common cause of liver disease.
Result
normal or raised
blood ammonia level
Test
Blood ammonia levels correlate with the severity of HE, but not all cases of hyperammonemia are associated with HE.[2] High ammonia levels alone do not have diagnostic, staging, or prognostic value for patients with HE.[1][22] A normal value warrants diagnostic reevaluation.[1] Testing may be helpful in patients with undifferentiated coma for which low ammonia levels make HE less likely.[22]
European guidelines recommend checking plasma ammonia levels in all patients with delirium/encephalopathy and liver disease, as they are considered to have a high negative predictive value in relation to a working diagnosis of HE and a normal value would bring the diagnosis of HE into question.[2]
Result
raised
urine culture
Test
Routine culture of urine can identify potential precipitating causes such as urinary tract infection. HE is a symptom of infection, so bacteriuria and culture positivity should be treated.
Result
may be positive
blood culture
Test
Routine culture of blood can identify potential precipitating causes such as bacteremia, spontaneous bacterial peritonitis, and other infections.
Result
may be positive
urine toxin screen
Test
Carried out to investigate use of opioids, sedatives, or drugs of abuse.
Result
may be positive for toxins
ultrasonography
Test
Rules out acute thrombosis of the portal or hepatic vein as a precipitating factor.
An upper-quadrant abdominal ultrasound should be considered in all patients with unexplained acute decompensation.
Result
may show thrombosis of portal or hepatic vein
head CT or MRI scan
Test
A head CT or MRI scan should be performed if there are diagnostic doubts or nonresponse to treatment. It is always warranted if there is clinical suspicion of intracerebral hemorrhage, stroke, or a space-occupying lesion.[2]
CT scan may also demonstrate evidence of cerebral edema or atrophy.
The yield is low in patients with cirrhosis and recurrent HE.[24]
Result
absence of other causes and presence of edema
Tests to consider
EEG
Test
An EEG may help in diagnosing mild HE and in excluding occult seizure activity in comatose patients.[2] HE may be associated with a decrease in brain wave frequency and amplitude.
Result
decrease in brain wave frequency and amplitude
lumbar puncture
Test
Lumbar puncture (LP) may be considered when there is concern for meningitis or other central nervous system process. In HE, results should be normal. LP is not indicated in the overwhelming majority of patients with suspected HE.
Result
normal cell count and protein levels
abdominal paracentesis
Test
In patients with ascites admitted with potential HE, a diagnostic paracentesis should be performed to rule out spontaneous bacterial peritonitis, which may precipitate HE.
Result
normal peritoneal fluid neutrophil count; elevated if spontaneous bacterial peritonitis is present
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