Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

OAU
80619
0 Negative
1 0.35-0.69 Equivocal
2 0.70-3.49 Positive
3 3.50-17.4 Positive
4 17.5-49.9 Strongly positive
5 50.0-99.9 Strongly positive
6 > or =100 Strongly positive Reference values
apply to all ages.
Clinical References: Homburger HA: Allergic diseases. In Clinical Diagnosis and Management
by Laboratory Methods. 21st edition. Edited by RA McPherson, MR Pincus. New York, WB Saunders
Company, 2007, Chapter 53, Part VI, pp 961-971
Organic Acids Screen, Urine
Clinical Information: Organic acids occur as physiologic intermediates in a variety of metabolic
pathways. The organic acidurias are a group of disorders in which one or more of these pathways are
blocked, resulting in a deficiency of normal products and an abnormal accumulation of intermediate
metabolites (organic acids) in the body. These excess metabolites are excreted in the urine. The incidence
of individual inborn errors of organic acid metabolism varies from 1:10,000 to >1:1,000,000 live births.
Collectively, their incidence approximates 1:3,000 live births. This estimate, however, does not include
other inborn errors of metabolism (ie, amino acid disorders, urea cycle disorders, congenital lactic
acidemias) for which diagnosis and monitoring may also require organic acid analysis. All possible
disease entities included, the incidence of conditions where informative organic acid profiles could be
detected in urine is likely to approach 1:1,000 live births. Organic acidurias typically present with either
an acute life-threatening illness in early infancy or unexplained developmental delay with intercurrent
episodes of metabolic decompensation in later childhood. There are multiple clinical instances where
organic acid analysis would be beneficial. A situation of severe and persistent metabolic acidosis of
unexplained origin, elevated anion gap, and severe neurologic manifestations, such as seizures, should be
considered strong diagnostic indicators of one of these diseases. The presence of ketonuria, occasionally
massive, provides an important clue toward the recognition of disorders, especially in the neonatal period.
Hyperammonemia, hypoglycemia, and lactic acidemia are frequent findings, especially during acute
episodes of metabolic decompensation.
Useful For: Diagnosis of inborn errors of metabolism
Interpretation: An abnormal organic acid analysis is not sufficient to conclusively establish a
diagnosis of a particular disorder. It is strongly recommended to seek confirmation by an independent
method, typically by in vitro enzyme assay (blood or cultured cells, tissue biopsy) or molecular analysis.
Rather than on individual abnormal values, interpretation is based on pattern recognition and correlation
of positive and negative findings (for example, ketotic versus nonketotic dicarboxylic aciduria). When no
significant abnormalities are detected, the organic acid analysis is reported and interpreted in qualitative
terms only. When abnormal results are detected, a detailed interpretation is given, including an overview
of the results and of their significance, a correlation to available clinical information, elements of
differential diagnosis, and recommendations for additional biochemical testing, and in vitro confirmatory
studies (enzyme assay, molecular analysis).
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Goodman SI, Markey SP: Diagnosis of organic acidemias by gas
chromatography-mass spectrometry. New York, Alan R Liss, 1981 2. Sweetman L: Organic acid analysis.
In Techniques in Diagnostic Human Biochemical Genetics. Edited by FA Hommes. Wiley-Liss, New
York, 1991, pp 143-176 3. Lehotay DC, Clarke JT: Organic acidurias and related abnormalities. Crit Rev
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