Metabolic Disorders Flashcards
Which disorders does the Guthrie blood spot test screen for?
Phenylketonuria, congenital hypothyroidism, cystic fibrosis, sickle cell disease, medium chain acyl-co-A dehydrogenase deficiency, maple syrup urine disease, isovaleric acidaemia, glutaric aciduria type 1, homocystinuria
What is phenylketonuria?
Phenylalanine hydroxylase deficiency
What is congenital hypothyroidism?
Dysgenesis or agenesis of the thyroid gland
What is specificity?
The probability that someone without the disease will correctly test negative
What is sensitivity?
The probability that someone with the disease will correctly test positive
What is positive predictive value?
The probability that someone who tests positive actually has the disease
What is negative predictive value?
The probability that someone who tests negative actually doesn’t have the disease
Name an organic acidaemia
Propionic acidaemia, isovaleric acidaemia
Describe the key clinical features of organic acidaemias
High urea and ketones, metabolic acidosis. May have a funny smell from organic acids
How are organic acidaemias managed?
Low protein diet, acylcarnitine, and haemofiltration
Name one of the nine urea cycle disorders
Ornithine transcarbamylase deficiency
Describe the key clinical features of urea cycle disorders
High ammonia (>200uM) leading to encephalopathy and developmental delay. Respiratory alkalosis. Vomiting
How are urea cycle disorders managed?
Low protein diet to stop urea formation
Name two amino acidopathies
Maple syrup urine disease, phenylketonuria
Describe the key clinical features of phenylketonuria
High phenylalanine, blue eyes, fair hair and skin, retardation