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Table 1 Clinical signs and symptoms of acute and chronic presentations of UCDs, and triggering factors for hyperammonemia in UCD patients

From: Suggested guidelines for the diagnosis and management of urea cycle disorders

Acute presentation

Chronic presentation

· Altered level of consciousness (from somnolence and lethargy to coma) mimicking encephalitis or drug intoxication

· Confusion, lethargy, dizziness

 

· Migraine-like headaches, tremor, ataxia, dysarthria

· Acute encephalopathy (see below)

· Asterixis (in adults)

· Seizures (generally not isolated but along with an altered level of consciousness)

· Learning disabilities, neurodevelopmental delay, mental retardation

· Ataxia (generally associated with altered consciousness level)

· Chorea, cerebral palsy

· Stroke-like episodes

· Protracted cortical visual loss

· Transient visual loss

· Progressive spastic diplegia or quadriplegia (described in ARG1D and HHH syndrome)

· Vomiting and progressive poor appetite

· Protein aversion, self-selected low-protein diet

· Liver failure

· Abdominal pain, vomiting

· Multiorgan failure

· Failure to thrive

· Peripheral circulatory failure

· Hepatomegaly, elevated liver enzymes

· “Post-partum psychosis”

· Psychiatric symptoms: hyperactivity, mood alteration, behavioural changes, aggressiveness

· Psychiatric symptoms (hallucinations, paranoia, mania, emotional or personality changes)

· Self-injurious behaviour

 

· Autism-like symptoms

 In neonates: 

· Fragile hair (typical for ASLD)

· sepsis-like picture, temperature instability

· respiratory distress, hyperventilation

· Dermatitis

 

· Specific neuropsychological phenotype in heterozygous OTC females

 

· Episodic character of signs and symptoms

Potential triggers of hyperammonemic crises in UCD patients

· Infections

· Fever

· Vomiting

· Gastrointestinal or internal bleeding

· Decreased energy or protein intake (e.g. fasting pre surgery, major weight loss in neonates)

· Catabolism and involution of the uterus during the postpartum period (mostly OTC females)

· Chemotherapy, high-dose glucocorticoids

· Prolonged or intense physical exercise

· Surgery under general anesthesia

· Unusual protein load (e.g. a barbecue, parenteral nutrition)

· Drugs: Mainly valproate and L-asparaginase/pegaspargase. Topiramate, carbamazepine, phenobarbitone, phenytoine, primidone, furosemide, hydrochlorothiazide and salicylates have also been associated with hyperammonemic decompensation.

  1. Typical and uncommon signs and symptoms are highlighted in bold- and normal-type, respectively, whereas italic type marks signs and symptoms reported in single patients. Grade of recommendation, D.