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Organic acidemias

Olaf A Bodamer, MD, PhD, FAAP, FACMG
Section Editors
Sihoun Hahn, MD, PhD
Marc C Patterson, MD, FRACP
Deputy Editor
Elizabeth TePas, MD, MS


Organic acidemias, also known as organic acidurias, are a group of disorders characterized by increased excretion of organic acids in urine. They result primarily from deficiencies of specific enzymes in the breakdown pathways of amino acids. Enzyme deficiencies in beta oxidation of fatty acids or carbohydrate metabolism cause elevated levels of non-amino organic acids. Abnormal organic acid levels also are found in the urine of some patients with mitochondrial disease [1].

Most organic acidemias become clinically apparent during the newborn period or early infancy. After an initial period of well-being, affected children develop a life-threatening episode of metabolic acidosis characterized by an increased anion gap. This presenting episode may be mistaken for sepsis and, if unrecognized, is associated with significant mortality.

Children with an organic acidemia are susceptible to metabolic decompensation during episodes of increased catabolism, such as intercurrent illness, trauma, surgery, or prolonged episodes of fasting. Parents and clinicians must be well informed about the initial signs of decompensation and trained in applying an emergency regimen [2,3]. Surgeons and anesthesiologists should be aware of potential complications and their prevention during anesthesia and surgery.

Diagnosis has been facilitated through the use of gas chromatograph-mass spectrometry (GC-MS) and tandem mass spectrometry [4]. Prenatal diagnosis is available for most disorders by detection of diagnostic compounds in amniotic fluid, by analysis of enzyme activities in amniocytes or chorionic villi, by molecular analysis, or by a combination of the three [5]. Diagnosis also may be made through newborn screening by tandem mass spectrometry, which is available in all states of the United States, Australia, and many European and Asian countries [6].


Organic acidemias can be classified as follows [1,7-9]:


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Literature review current through: Sep 2016. | This topic last updated: Sep 21, 2015.
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