Lecture 3 AMMONIA

How is Ammonia created?

DEAMINATION of amino acids - PROTEIN METABOLISM

What is the cycle that gives us Ammonia?

Proteins → amino acids → deamination → ammonia

How else can we get ammonia?

BACTERIAL metabolism in the INTESTINE

At normal blood pH what does ammonia exist as?

SINCE AMMONIA IS TOXIC it is in the AMMONIUM form

What does the excretion of Ammonium help with?

BUFFERING the urine

Secreted by the kidneys

If ammonia goes to the Kidneys what happens to it?

Secreted as AMMONIUM

If ammonia goes to the LIVER what is it converted to?

UREA

What are the 4 reasons for measuring Ammonia?

1. Prognosis/severity of REYE SYNDROME

2. Liver disease

3. Deficiencies of UREA CYCLE ENZYMES

4. Hyperalimentation therapy MONITORING

What happens if you have LIVER DYSFUNCTION?

Ammonia conversion to UREA is DECREASED

What is the main risk associated with INCREASED AMMONIA in blood?

AFFECT THE BRAIN

What is HYPERammonemia?

Abnormally HIGH AMMONIA in blood

What can cause HYPERammonemia?

LIVER DISEASE such as cirrhosis

Urea cycle enzyme deficiency

Encephalopathy

What happens if ammonia isnt converted to urea?

REMAINS in the BLOOD CIRCULATION

Why is HIGH Ammonia dangerous?

NEUROTOXICITY

How does high Ammonia blood concentration affect the brain?

ALTER brain METABOLISM

Impairs BRAIN CELL function (astrocyte)

What is the ENZYMATIC method of measuring Ammonia?

Utilize the enzyme GLDH

measuring ammonia or ammonium

What is the ION-Selective Electrode (ISE) analytical method?

DIRECTLY measures ammonia

Which anticoagulants can be used for Ammonia specimens? (you know this)

EDTA and HEPARIN

What is the MOST IMPORTANT aspect of specimen handling of ammonia?

Placing ammonia specimens on ICE IMMEDIATELY

Ammonia should be tested ASAP

What should be avoided for Ammonia specimens?

Patient SMOKING several hours before

HEMOLYSIS