Hyperaminoacidurias

Question 1

What is hyperaminoaciduria?

Answer 1

Increase in the renal excretion (urination) of amino acids

Question 2

What does the term “prerenal” mean?

Answer 2

Something that occurs before the kidney is affected.

Question 3

What is hyperargininemia?

Answer 3

Genetic condition that leads to an increase in plasma arginine (Arg) levels. Although reabsorption of Arg is increased, the increased levels are higher than the Tm (transport maximum) and this results in Arg being excreted into the urine.

Question 4

Which solutes does the heterodimeric SLC7A9/SLC3A1 transporter carry across the apical membrane of the nephron? (3)

Answer 4

1. Arginine (Arg)
2. Lysine (Lys)
3. Ornithine

Question 5

When a transporter carries multiple solutes, what needs to be taken into account?

Answer 5

Competition between the solutes

Question 6

Out of arginine, lysine, and ornithine, which 2 solutes have constant metabolic production that does not change?

Answer 6

1. Lysine (Lys)

2. Ornithine

Question 7

Which amino acids have ring structures? (3)

Answer 7

1. Phenylalanine (Phe)
2. Tryptophan (Trp)
3. Tyrosine (Tyr)

Question 8

Which amino acids have neutral structures? (2)

Answer 8

1. Alanine (Ala)

2. Serine (Ser)

Question 9

Which amino acids are unable to be transported in Hartnup disease?

Answer 9

Those with neutral and ring structures.

Question 10

What are 3 cationic amino acids?

Answer 10

1. Arginine (Arg)
2. Lysine (Lys)
3. Orthinine

Question 11

In cystinuria, which amino acids are unable to be transported?

Answer 11

Cysteine and cationic amino acids

Question 12

An increased filtered load of an amino acid leads to?

Answer 12

Increased excretion (urination) of the amino acid from the body.

Question 13

What is nephrolithiasis synonymous with?

Answer 13

Kidney stones

Question 14

What is the cause of nephrolithiasis?

Answer 14

Increased excretion of poorly soluble cysteine

Question 15

Lysinuric Protein Intolerance (LPI) is a illness that has defective reabsorption of what 2 compounds?

Answer 15

1. Lysine (Lys)

2. Arginine (Arg)

Question 16

What does the reduced levels of Lys and Arg in LPI result in? (2)

Answer 16

1. Impairs the urea cycle

2. Impairs detoxification of ammonium

Question 17

What is hyperammonemia?

Answer 17

Excess ammonia in the blood. Can be toxic.

Question 18

What are 3 secondary causes that result from LPI?

Answer 18

1. Alveolar proteinosis
2. Hepatosplenomegaly
3. Mental deterioration

Question 19

What is the defective transporter in LPI usually responsible for?

Answer 19

Efflux of Arg and Lys into the blood in exchange for Na+ and neutral amino acids.

(Arg and Lys INTO blood ; Na+, neutral amino acids INTO tubule)

Question 20

Where is the defective transporter in LPI usually located?

Answer 20

Basolateral membrane of the proximal tubule

Question 21

Is the Fanconi Syndrome inherited genetically or is it acquired?

Answer 21

Both!

Question 22

What is happening in the Fanconi Syndrome?

Answer 22

Loss of function in the proximal tubule, which leads to deficiencies in reabsorption of essential nutrients.

Question 23

What essential nutrients is the proximal tubule responsible for reabsorbing? (6)

Answer 23

1. Na+
2. K+
3. Cl-
4. HCO3-
5. Glucose
6. Amino acids