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

From: Hyperammonaemia in classic organic acidaemias: a review of the literature and two case histories

Triggers Clinical signs and symptoms Biochemical signs
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)
  1. Abbreviation: HCO3 Bicarbonate, MMA Methylmalonic acidaemia, PA Propionic acidaemia