[01] Sultan Kaba, Department of Paediatrics, School of Medicine, Yuzuncu Yil University, Van, Turkey. [02] Nihat Demir, Department of Paediatrics, School of Medicine, Yuzuncu Yil University, Van, Turkey. [03] Keziban Bulan, Department of Paediatrics, School of Medicine, Yuzuncu Yil University, Van, Turkey. [04] Murat Dogan, Department of Paediatrics, School of Medicine, Yuzuncu Yil University, Van, Turkey. [05] Kaan Demiroren, Department of Paediatrics, School of Medicine, Yuzuncu Yil University, Van, Turkey. [06] Nesrin Ceylan, Department of Paediatrics, School of Medicine, Yuzuncu Yil University, Van, Turkey.

Most organic acidemias become clinically apparent during neonatal period or early infancy. Infants typically have severe metabolic acidosis with increased anion gap, ketosis and hyperammonemia. Extremely high ammonia levels exceeding 1000 µmol/L is a discriminative feature for urea cycle defect while levels exceeding 200-300 µmol/L are rarely encountered in other reasons of hyperammonemia. Lethargy developed in a boy with extremely high ammonia levels (3693 µmol/L) on the post-natal day 3. Higher extremes in ammonia are mainly observed in urea cycle defects. We presented this case which was diagnosed as methylmalonic acidemia by specific tests to emphasize that extremely high ammonia levels can be seen in organic acidemias.

Organic Acidemia, Hyperammonemia, Methylmalonic Academia, Urea Cycle Defects

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