Ammonia metabolism, transport and toxicity

Quick Orientation

Section	Objective	Keywords
Definition	Understand the core idea	Ammonia (NH3), ammonium (NH4+), 10 to 20 mg/dL
Formation of Ammonia	Learn the main facts and relationships	transamination and deamination, urease
Transport and Storage	Learn the main facts and relationships	glutamine, alanine, glucose-alanine cycle
Functions of Ammonia	Learn the main facts and relationships	acid-base balance
Toxicity of Ammonia	Learn the main facts and relationships	glutamate dehydrogenase, α-ketoglutarate
Clinical Correlation	Connect the mechanism to clinical findings	Hyperammonemia, sodium benzoate and phenylacetate, Hemodialysis

Section

Definition

Objective: Understand the core idea
Keywords: Ammonia (NH3), ammonium (NH4+), 10 to 20 mg/dL

Formation of Ammonia

Objective: Learn the main facts and relationships
Keywords: transamination and deamination, urease

Transport and Storage

Objective: Learn the main facts and relationships
Keywords: glutamine, alanine, glucose-alanine cycle

Functions of Ammonia

Objective: Learn the main facts and relationships
Keywords: acid-base balance

Toxicity of Ammonia

Objective: Learn the main facts and relationships
Keywords: glutamate dehydrogenase, α-ketoglutarate

Clinical Correlation

Objective: Connect the mechanism to clinical findings
Keywords: Hyperammonemia, sodium benzoate and phenylacetate, Hemodialysis

Definition

Ammonia (NH3) is constantly liberated from amino acid and other nitrogenous-compound metabolism; at physiological pH it exists as the ammonium (NH4+) ion.