Table 1 Summary of case presentation and acute medical treatment

1

Female

3 days

Apnea, convulsions, depressed consciousness, encephalopathy, lethargy, metabolic acidosis, oliguria, poor feeding/sucking, seizures, tachypnea, and unresponsiveness

Presenting: 1257 µmol/L (reference range < 77 µmol/L)

Peak: 1500 µmol/L.

During the presenting episode, hyperammonemia (> 100 µmol/L) was present for 6 days.

Glutamine (2132 µmol/L; ref: 246–984),

urine orotic acid (14.8 mmol/mol creatinine; ref: 2.6–5.8)

Intravenous (IV) Sodium phenylbutyrate and sodium benzoate, hemodialysis followed by continuous veno-venous hemofiltration (CVVH), IV arginine, parenteral nutrition (TPN) with low protein and age-appropriate calories

None

2

Female

6 days

Abdominal distension, breathing difficulty, confusion, dehydration, drowsiness, encephalopathy, grunting, hypothermia, hypotonia, poor feeding, respiratory distress, and vomiting; Consanguinity

Presenting: >700 µmol/L (ref < 100 µmol/L)

Peak concentration and number of days with elevated ammonia not available

Glutamine (793 µmol/L; ref: 229–684)

Hemodialysis for three days with two temporary discontinuations due to coagulated filters, IV sodium phenylacetate, and sodium benzoate.

Four additional episodes of hyperammonemia, with a total of three days with ammonia > 100 µmol/L

3^a

Male

38 years

Asterixis, ataxia, behavioral problems, combativeness, confusion, depressed consciousness, drowsiness, encephalopathy, headaches, irritability, nausea, spasticity, and vomiting

Presenting: 434 µmol/L (ref: 15–50 µmol/L) at presentation.

Peak concentration not available.

During the presenting episode, hyperammonemia (> 100 µmol/L) was present for 8 days.

Glutamine (1062 µmol/L; ref: 104–750)

Sodium phenylbutyrate and citrulline (50 mg/kg/day)

Four additional episodes of hyperammonemia, but the concentration did not exceed 100 µmol/L

4

Male

25 months

Altered mental status, breathing difficulty, developmental delay, disconjugate gaze, encephalopathy, hyperpnea, irritability, metabolic acidosis, pallor, poor capillary refill, poor feeding, and vomiting

Presenting: 120 µmol/L (ref: 21–50 µmol/L)

Peak: 185 µmol/L.

During the presenting episode, hyperammonemia (> 100 µmol/L) was present for 2 days.

Glutamine (1448 µmol/L; ref: 410–700),

citrulline (9 µmol/L; ref: 10–60),

urine orotic acid (7.3 mmol/mol creatinine; ref: 0.7–5.1),

urine ketones (3+),

urine protein (1+)

Sodium phenylbutyrate, 10% dextrose water and ½ normal saline at 1.5 x maintenance (D10W ½ NS at 1.5 x M), and IV citrulline (170 mg/kg/day).

Four additional episodes of hyperammonemia, but the concentration did not exceed 100 µmol/L

5

Female

14 years

Abdominal pain, headaches, hypertonia, lethargy, nausea, protein aversion, and vomiting; family history of a sister diagnosed with NAGS deficiency as an infant.

Presenting: 95 µmol/L (ref: 11–35 µmol/L)

Peak: 223 µmol/L.

During the presenting episode, hyperammonemia (> 100 µmol/L) was present for 2 days.

Not available

Sodium phenylbutyrate and IV dextrose 12.5, ½ NS at two times maintenance

Several documented episodes but details are not available

6^b

Female

10 years

Ataxia, encephalopathy, nausea, protein aversion, vomiting, dizziness, and syncope; family history of a cousin with seizures.

Presenting: 203 µmol/L (ref: 9–33 µmol/L)

Peak: 293 µmol/L.

During the presenting episode, hyperammonemia (> 100 µmol/L) was present for 2 days.

Glutamine (868 µmol/L, ref: 49–736),

urine orotic acid (4.1 mmol/mol creatinine, ref: 0.2–1.2),

ketones (4+)

Sodium benzoate, sodium phenylacetate, and IV arginine

18 additional episodes of hyperammonemia, with a total of 30 days with ammonia greater than 100 µmol/L

7

Male

2 years

Abdominal pain, confusion, feeding intolerance, poor feeding, seizures, and vomiting.

Details not available in chart

Glutamine (970 µmol/L; ref: 205–756),

citrulline (63 µmol/L, ref: 12–55)

Sodium phenylbutyrate, sodium benzoate, and IV arginine

35 additional episodes of hyperammonemia, with a total of 19 days with ammonia > 100 µmol/L