Metabolic Flashcards
How do you calculate anion gap
(Na+K+) - (chloride + bicarbonate)
Most common organic acidaemias
Methylmalonic and propionic acidaemia
The Urea Cycle part 1
Glutamate + acetyl-CoA forms N-acetylglutamate
Enzyme = N-acetylglutamate synthetase
Urea Cycle part 2
Ammonia + bicarbonate forms carbamoyl phosphate
Only in presence of N-acetylglutamate
catalysed = carbamoyl phosphate synthetase
Urea cycle part 3
Carbamoyl phosphate + ornithine = citrulline
Where does part 1- 3 occur?
Mitochondrial matrix
Urea Cycle part 4
Occurs in cytoplasm
Citrulline + aspartate to form arginosuccinate
Urea Cycle part 5
Argininosuccinate lyase cleaves argininosuccinate to arginine
Urea Cycle Part 6
Arginine is hydrolysed to urea + ornithine
Ornithine is transported to mitochondrion for part 3
Normal ammonia levels
<100
How are urea cycle disorders inherited
Autosomal recessive
Except ornithine transcarbamylase = X-linked
Acute management of Urea cycle disorders
Stop feeds
Commence 10% dextrose to reduce nitrogen load on cycle
IV ammonia
IV arginine
Chronic management of urea cycle disorder
Low protein diet
Gluconeogenesis
Synthesis of glucose from non-glucose precursors
Glycolysis
Oxidation of glucose to pyruvate with generation of ATP
Glycogenesis
Conversion of excess glucose to glycogen
Glycogenolysis
Degration of glycogen to glucose
GSD 1
Deficiency of glucose-6-phosphate
Inability to mobilize glucose from glycogen or utilise glucose from gluoneogeneis
Why do patients with GSD have heptaomegly
Glycogen storage
Which GSD’s present with hepatic presentation
Ia
Ib
III
IV
VI IX O
Which GSD’s present with muscular presentation
V, VII, X, XI, XII, XIII
Which present with a cardiac presentation
II
III
What is the most common muscle glycogenesis
GSD 5 - McArdle’s disease
How does McArdle’s present
Muscle pain, cramps and fatigue during brief intense exercise
Resume exercise after brief rest
