What is a typical normal range for serum ammonia?

• A. 15-45 µg/dL
• B. 0-10 µg/dL
• C. 100-150 µg/dL
• D. 3.5-5.0 mEq/L

Answer: (A)

Normal serum ammonia levels reflect the liver’s ability to detoxify ammonia produced by protein breakdown in the gut through the urea cycle. In adults, the typical reference range is about 15 to 45 micrograms per deciliter. Values within this range are considered normal and don’t indicate hepatic dysfunction. Higher levels point to hepatic impairment or conditions that increase ammonia production, such as severe liver disease or urea cycle disorders, and can contribute to hepatic encephalopathy if not treated. The other ranges are not consistent with a normal ammonia measurement, and one of them represents a potassium value, not ammonia.