Gastrointestinal System Disorders Q 42 - Gyan Darpan : Learning Portal
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Saturday 16 April 2022

Gastrointestinal System Disorders Q 42

Hepatic encephalopathy develops when the blood level of which substance increases?
    A. Ammonia
    B. Amylase
    C. Calcium
    D. Potassium

Correct Answer: A. Ammonia

Ammonia levels increase d/t improper shunting of blood, causing ammonia to enter systemic circulation, which carries it to the brain. Under normal conditions, ammonia is produced by bacteria in the gastrointestinal tract (e.g., breakdown product of amines, amino acids, purines, and urea) followed by metabolism and clearance by the liver. In the case of cirrhosis or advanced liver dysfunction, however, there is either a decrease in the number of functioning hepatocytes, portosystemic shunting, or both, resulting in decreased ammonia clearance and hyperammonemia.

Option B: Amylase is indirectly affected in hepatic encephalopathy. Hepatic encephalopathy (HE) is a reversible syndrome observed in patients with advanced liver dysfunction. The syndrome is characterized by a spectrum of neuropsychiatric abnormalities resulting from the accumulation of neurotoxic substances in the bloodstream (and ultimately in the brain).
Option C: Elevated blood ammonia levels, not calcium levels, are often seen in patients with hepatic encephalopathy. It is more useful, however, to assess the clinical improvement or deterioration of a patient undergoing treatment rather than monitor serial arterial blood ammonia measurements.
Option D: Once ammonia crosses the blood-brain barrier, it has multiple neurotoxic effects. These include alterations in molecular transport (e.g., amino acids, electrolytes, water) in astrocytes and neurons, increased synthesis of glutamine from glutamate by astrocytes, inhibition of excitatory and inhibitory postsynaptic potential generation, impaired amino acid metabolism, and impaired energy utilization as a result of increased GABA activity.

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