special subjects
Alcohol Toxicity and Withdrawal
Diagnosis of Alcohol Toxicity and Withdrawal
Usually a clinical diagnosis Acute intoxication: Sometimes blood alcohol content (BAC) and a rapid blood glucose test Chronic use: Complete blood count, magnesium, liver tests, and PT/PTT Withdrawal: Evaluation to rule out central nervous system injury and infection Diagnosis is usually made based on typical Symptoms and Signs . Inacute alcohol intoxication, laboratory tests are generally not helpful; diagnosis is usually made clinically. Exceptions include fingerstick glucose to rule out hypoglycemia and sometimes tests to determine BAC. Confirmation by breath or blood alcohol levels is useful for legal purposes (eg, to document intoxication in drivers or employees who appear impaired). BAC levels do not always correlate to level of intoxication; for a given BAC level, chronic drinkers may have less impairment compared to a person who does not drink regularly. However, finding a low BAC in patients who have altered mental status is helpful because it expedites the search for an alternate cause. Clinicians should not assume that a high BAC in patients with apparently minor trauma accounts for their obtundation, which may be due to intracranial injury or other abnormalities. Such patients should also have additional evaluation to search for evidence of trauma or toxicity due to other substances. Chronic alcohol abuseand dependence are clinical diagnoses; experimental markers of long-term use have not proved sufficiently sensitive or specific for general use. Screening tests such as AUDIT (Alcohol Use Disorders Identification Test) or theCAGE questionnairecan be used. However, heavy alcohol users may have a number of metabolic derangements that are worth screening for, so complete blood count, electrolytes (including magnesium), liver tests (including coagulation profile [PT/PTT]), serum ammonia, and serumalbuminare often recommended. In severe withdrawal and toxicity, symptoms may resemble those of central nervous system injury or infection. Because concomitant medical and surgical conditions can occur simultaneously with alcohol withdrawal, medical evaluation with CT and lumbar puncture may be needed. Patients with mild symptoms do not require routine testing unless improvement is not marked within 2 to 3 days. A clinical assessment tool for severity of alcohol withdrawal is available. 