Gamma-Hydroxybutyrate Toxicity Workup

Updated: May 12, 2022
  • Author: Theodore I Benzer, MD, PhD; Chief Editor: Sage W Wiener, MD  more...
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Laboratory Studies

Laboratory tests for gamma-hydroxybutyric acid (GHB) in serum or urine are not readily available. The diagnosis is made by history and physical examination. Reference laboratories can perform assays on blood and urine for GHB. These tests take time and are not useful clinically but can be very useful in legal cases (eg, drug-facilitated rape).

If the history is in question, a broad laboratory evaluation should be obtained to elucidate the cause of altered mental status. Such testing may include the following:

  • Complete blood cell count
  • Serum electrolyte levels
  • Liver function tests
  • Toxicologic screens
  • Ammonia level
  • Arterial blood gas levels
  • Osmolality
  • Cultures
  • Spinal fluid analysis
  • Pregnancy test 

Imaging Studies

Imaging will not help in making the diagnosis of GHB ingestion; however, brain imaging (CT or MRI) can be useful to rule out trauma or stroke. Chest radiography is important to exclude aspiration pneumonitis.


Other Tests

An electrocardiogram (ECG) and cardiac monitoring are important. GHB ingestions can be associated with bradycardia. U waves are frequently seen on the ECG even in the absence of hypokalemia. Other co-ingestions may have severe cardiovascular consequences.



Lumbar puncture and spinal fluid analysis may be indicated if CNS infection is a concern.