Amino Acids, Metabolic & Newborn Screening

Grade plasma ammonia by age group and severity, and see why sampling technique matters as much as the number itself.

Screen a raised anion gap against lactate, ketones and the osmolal gap to narrow the cause using the GOLDMARK framework.

Calculate the Fischer ratio of branched-chain to aromatic amino acids, used to assess hepatic encephalopathy risk and nutritional status in liver failure.

Convert homocysteine between mg/L, µg/mL and µmol/L, and see why a raised result points more often to B12 status than to cardiovascular risk.

Convert methylmalonic acid between µmol/L and nmol/L — the single most useful confirmatory test for functional B12 deficiency.

Calculate the phenylalanine to tyrosine ratio used to confirm phenylketonuria on newborn screening, and see when a raised phenylalanine is something else entirely.