Hyperaminoacidurias Flashcards
What is hyperaminoaciduria?
Increase in the renal excretion (urination) of amino acids
What does the term “prerenal” mean?
Something that occurs before the kidney is affected.
What is hyperargininemia?
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.
Which solutes does the heterodimeric SLC7A9/SLC3A1 transporter carry across the apical membrane of the nephron? (3)
- Arginine (Arg)
- Lysine (Lys)
- Ornithine
When a transporter carries multiple solutes, what needs to be taken into account?
Competition between the solutes
Out of arginine, lysine, and ornithine, which 2 solutes have constant metabolic production that does not change?
- Lysine (Lys)
2. Ornithine
Which amino acids have ring structures? (3)
- Phenylalanine (Phe)
- Tryptophan (Trp)
- Tyrosine (Tyr)
Which amino acids have neutral structures? (2)
- Alanine (Ala)
2. Serine (Ser)
Which amino acids are unable to be transported in Hartnup disease?
Those with neutral and ring structures.
What are 3 cationic amino acids?
- Arginine (Arg)
- Lysine (Lys)
- Orthinine
In cystinuria, which amino acids are unable to be transported?
Cysteine and cationic amino acids
An increased filtered load of an amino acid leads to?
Increased excretion (urination) of the amino acid from the body.
What is nephrolithiasis synonymous with?
Kidney stones
What is the cause of nephrolithiasis?
Increased excretion of poorly soluble cysteine
Lysinuric Protein Intolerance (LPI) is a illness that has defective reabsorption of what 2 compounds?
- Lysine (Lys)
2. Arginine (Arg)
What does the reduced levels of Lys and Arg in LPI result in? (2)
- Impairs the urea cycle
2. Impairs detoxification of ammonium
What is hyperammonemia?
Excess ammonia in the blood. Can be toxic.
What are 3 secondary causes that result from LPI?
- Alveolar proteinosis
- Hepatosplenomegaly
- Mental deterioration
What is the defective transporter in LPI usually responsible for?
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)
Where is the defective transporter in LPI usually located?
Basolateral membrane of the proximal tubule
Is the Fanconi Syndrome inherited genetically or is it acquired?
Both!
What is happening in the Fanconi Syndrome?
Loss of function in the proximal tubule, which leads to deficiencies in reabsorption of essential nutrients.
What essential nutrients is the proximal tubule responsible for reabsorbing? (6)
- Na+
- K+
- Cl-
- HCO3-
- Glucose
- Amino acids
