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An automated microassay for blood ammonia
Journal of Clinical Chemistry and Clinical Biochemistry. Zeitschrift Fur Klinische Chemie Und Klinische Biochemie
|April 1, 1979
Summary
A new microassay accurately measures blood ammonia (NH+4) using a continuous flow dialysis and colorimetric reaction. This method is precise, sensitive, and suitable for clinical diagnostics in humans and animal models.
Area of Science:
- Clinical Chemistry
- Analytical Chemistry
- Biochemistry
Background:
- Elevated blood ammonia levels are indicative of severe liver dysfunction.
- Accurate and sensitive measurement of ammonia is crucial for diagnosing and managing hepatic encephalopathy.
- Existing methods for ammonia quantification can be time-consuming or require large sample volumes.
Purpose of the Study:
- To develop and validate a microassay for quantifying blood ammonia.
- To establish a rapid, sensitive, and specific method for ammonia determination.
- To assess the assay's performance characteristics, including precision, accuracy, and sensitivity.
Main Methods:
- A microassay was developed involving sample dilution and continuous flow dialysis.
- Ammonium ions in the dialysate were quantified colorimetrically using the hypochlorite-phenol Berthelot reaction.
- Assay performance was evaluated for precision, accuracy, sensitivity, and specificity.
Main Results:
- The assay accurately measures ammonia concentrations from 1 to 400 mumol/l NH+4 in 50 mul whole blood, with potential for up to 800 mumol/l.
- The method demonstrated good precision, accuracy, sensitivity, and specificity.
- Reference values in humans were established: 27.4 +/- 10.2 mumol/l NH+4 in arterial blood and 20.9 +/- 9.8 mumol/l in venous blood.
- Similar reference values were observed in rats and mice.
Conclusions:
- A reliable microassay for blood ammonia has been successfully developed.
- The assay is suitable for determining ammonia levels in small blood volumes, applicable to human and animal studies.
- This method offers a valuable tool for clinical diagnostics and biochemical research requiring ammonia quantification.