Analytic Time

10 -14 days

MiChart Code
4-Hydroxybutyric acid (CSF)
Soft Order Code
4HYBA

Test Updated:

Synonyms
 

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Test Overview

Test Methodology

GC/MS

Test Usage

4-Hydroxybutyrate is useful for diagnosing Succinic semialdehyde (SSADH) deficiency. This testing may also be used for assessment of Variants of Uncertain Significance (VUS) identified during genetic testing (e.g. Next Generation Sequencing or Capillary Sequencing Testing). Succinic semialdehyde dehydrogenase (SSADH) deficiency causes decreased succinic acid production from gamma-aminobutyric acid (GABA) with shunting of the accumulated succinic semialdehyde intermediate to 4-Hydroxybutyric acid and subsequently, 3,4-Hydroxybutyric acid. Gamma-aminobutyric acid functions as both a metabolic intermediate in neuronal and extra-neuronal tissues and as a neurotransmitter in neural tissue. Gamma-aminobutyric acid is found predominantly in brain cells; however, it also occurs in kidney and B-cells of the pancreas. Gamma-aminobutyric acid (GABA) is converted to succinic semialdehyde by GABA transaminase. Succinic semialdehyde is either metabolized to gamma hydrozybutryate (GHB) by GHB dehydrogenase or to succinate by SSADH. Deficiency of SSADH causes the accumulation of GHB in body fluids, which causes the clinical manifestations of SSADH deficiency, also known as 4-hydroxybutyric aciduria. Interestingly, despite the presence of increased serum concentrations of the organic acids, 4-Hydroxybutyric acid and 3,4-Hydroxybutyric acid SSADH deficiency is not associated with an increased anion gap or a metabolic acidosis because the molar concentrations of these acids in the blood are not sufficiently high enough to cause these abnormalities. The phenotype is that of diffuse encephalopathy, most often as a static condition, comprising psychomotor delays, ataxia, hypotonia, dysfunctional or absent speech, and variable seizures.

Reference Range
 

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Specimen Requirements

Normal Volume
4.5 mL CSF
Minimum Volume
 

Billing Information

CPT Code
82542
Pro Fee Code
 
LOINC
 

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As the reference laboratory division of Michigan Medicine's Department of Pathology, MLabs shares the institution's commitment to applying established quality principles to clinical laboratory testing. Like other large organizations in complex, consequential fields, we rely on an established approach to monitor quality throughout the testing process.