A urine organic acids test is performed to screen people for certain inherited metabolic disorders, which are classified as organic acidemias, or organic acidurias. This test screens for the presence of abnormally high levels of metabolic products, the presence of which indicates the likelihood of an inborn error of metabolism. Urine is collected and checked for the presence of abnormal levels of organic acids, typically using gas chromatography with mass spectrometry. In most cases the urine organic acids test will identify the levels of as many as 63 different substances as either normal or elevated.
Organic acidemias typically show up in infancy or very early childhood, causing a wide range of symptoms. Indicators can include lethargy, seizures, vomiting, and failure to thrive. The symptoms of metabolic problems may be subtle, but they may also be the underlying cause of other significant health problems including liver failure, coma, and osteoporosis. Damage to other organs is common, as is the destruction of parts of the central nervous system. While it is possible to treat the symptoms, it is usually necessary to use a urine organic acids test to uncover the reason behind the trouble, and determine the most effective treatment.
Since there are more than five dozen types of organic acidemias, it is important that the urine organic acids test check for a wide range of the acids that may indicate the presence of one or more of these. Three of the main types of acidemias are maple syrup urine disease, methylmalonic acidemia, and propionic acidemia, though other types may be present alone or in combination with these. One of the difficulties of using the urine organic acids test is that the problem may be intermittent, resulting in inaccurate test results; some urine specimens will not have any excess of organic acids present, but will instead show normal levels. If acidemia is still suspected, the best course is for the physician to collect urine from different days and times, and check them all.
When an organic acidemia has been identified, it is vital to begin treatment as quickly as possible. In some cases the prognosis is death, and in most cases treatment is to use effective supportive care, as in many cases there is nothing that can be done for the condition. Care includes such things as a limited diet, typically containing few proteins and very high in carbohydrates, the substitution of amino acids, and vitamin therapy. Patients may also require intravenous fluids and in some cases must be fed with a gastric tube instead of being able to eat normally.