A method for measuring ammonia in a blood sample may involve positioning the blood sample in proximity with an ammonia gas sensor, generating a current with the ammonia gas sensor in response to ammonia gas released from the blood sample, and measuring the current generated by the ammonia gas sensor, using a current measurement member coupled with the ammonia gas sensor. A device for measuring an ammonia level in a blood sample may include a blood sample containment member, an ammonia gas sensor coupled with the blood sample containment member, and a current measurement member coupled with the ammonia gas sensor. The method and device may be used to measure an ammonia level in a blood sample as small as one drop of blood, or approximately 0.05 mL of blood.