Urea cycle disorders are rare genetic conditions caused by enzyme deficiencies that prevent the body from removing ammonia from the bloodstream. They are caused by mutations in genes encoding six specific enzymes responsible for converting toxic ammonia into urea for elimination. The Ammonia Plasma test is the most important test for diagnosis because it directly measures ammonia accumulation in the blood.
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Urea cycle disorders are caused by genetic mutations that result in deficiencies of one or more of the six enzymes in the urea cycle: carbamoyl phosphate synthetase I, ornithine transcarbamylase, argininosuccinate synthetase, argininosuccinate lyase, arginase, or N-acetylglutamate synthase. These enzymes work together to convert toxic ammonia, a byproduct of protein breakdown, into urea that can be safely eliminated through urine. When any of these enzymes are deficient or absent, ammonia accumulates in the bloodstream and reaches dangerous levels that can damage the brain and nervous system.
The Ammonia Plasma test is the most important test for urea cycle disorders because it directly measures the level of toxic ammonia in your blood. Elevated ammonia levels (hyperammonemia) are the primary indicator that urea cycle enzymes are not working properly, allowing ammonia to accumulate instead of being converted to urea for safe elimination. This test is essential for early detection because high ammonia levels can quickly reach the brain and cause irreversible damage, seizures, coma, or death if left untreated. Additional tests including amino acid analysis and genetic testing may follow to identify which specific enzyme is deficient.
You should get tested if you or your child experience unexplained vomiting, lethargy, confusion, seizures, or other neurological symptoms, especially after consuming high-protein meals or during illness. Newborns who are unusually sleepy, refuse to eat, have rapid breathing, or show poor muscle tone should be tested immediately. Individuals with a family history of urea cycle disorders or unexplained infant deaths should consider testing. Testing is also important if you experience recurring episodes of confusion or behavioral changes that seem to worsen with protein intake or stress.
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What this means
Your plasma ammonia level is elevated above the optimal range. This may indicate that your liver is having difficulty converting ammonia to urea for elimination, which can contribute to symptoms like fatigue, confusion, or difficulty concentrating. Elevated ammonia requires medical attention to identify the underlying cause and prevent further complications.
Recommended actions
Follow up with your doctor or a liver specialist to discuss results and underlying causes
Consider reducing dietary protein intake if recommended by your healthcare provider
Stay well-hydrated to support kidney function and toxin elimination
Avoid alcohol completely and discuss any medications that may affect liver function
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