Table 1 Triggers, clinical signs and symptoms, and biochemical signs of acute decompensation in PA and MMA [3]

Infection

Poor feeding

Metabolic acidosis:

• pH < 7.3

• anion gap > 20 mmol/L

• low HCO₃⁻ or base excess <−5 mmol/L)

Fever

Vomiting

Prolonged fasting

Lethargy

Medication (e.g. chemotherapy, high-dose glucocorticoids)

Seizures

Surgery and/or general anaesthesia

Irritability

Elevated blood lactate (> 3 mmol/L)

Acute trauma

Respiratory distress

Hyperammonaemia:

• > 75 μmol/L associated with symptomatic decompensation

• > 200 μmol/L associated with impaired vigilance [5]

Significant haemorrhage

Hypothermia

Psychological stress

Dehydration

Excessive protein intake

Weight loss

Excessive physical exertion

Ketonuria (> trace in infants or > + in children)

Neutropenia

Thrombocytopenia