What labs should be ordered for a patient exposed to hydrochloric acid and bleach?

Laboratory Evaluation for Hydrochloric Acid and Bleach Exposure

For a patient exposed to hydrochloric acid and bleach, immediately order: CBC, comprehensive metabolic panel (sodium, potassium, chloride, magnesium, calcium), arterial blood gas with pH and lactate, liver function tests (bilirubin, ALT, AST), and β-HCG in women of childbearing age. 1

Essential Initial Laboratory Tests

The following labs should be obtained urgently to assess for systemic toxicity and guide management:

Electrolytes and Acid-Base Status

• Serum sodium, potassium, chloride, magnesium, and calcium - Critical because hydrochloric acid exposure can cause severe electrolyte derangements including hyponatremia, hypokalemia, and hypocalcemia 1
• Arterial blood gas with pH and serum lactate - Essential to detect metabolic acidosis, which is a key indicator of transmural necrosis and poor prognosis 1
• Serum bicarbonate - The combination of bleach (sodium hypochlorite) and hydrochloric acid produces chlorine gas and can cause hyperchloremic metabolic acidosis 2, 3

Hematologic and Hepatic Assessment

• Complete blood count (CBC) - Leukocytosis may indicate transmural injury or infection 1
• Liver function tests (bilirubin, ALT, AST) - Deranged values predict transmural necrosis and guide surgical decision-making 1
• Urea and creatinine - Assess renal function and volume status 1

Additional Considerations

• β-HCG in young women - Mandatory to rule out pregnancy before imaging or interventions 1
• Blood alcohol level - Often relevant in intentional ingestions 1

Critical Laboratory Findings That Predict Severe Injury

Severe acidosis (low pH, elevated lactate) and deranged liver function tests are predictive of transmural necrosis requiring emergency surgical intervention. 1

High-Risk Laboratory Patterns

• Hyperchloremic metabolic acidosis - The reaction between bleach and hydrochloric acid produces hypochlorous acid and chlorine, leading to hyperchloremia (often >140 mEq/L) and metabolic acidosis 2, 3
• Severe hypernatremia - Bleach ingestion provides a massive sodium load (household bleach contains 10% sodium hypochlorite); levels >169 mEq/L have been reported in fatal cases 2, 3
• Elevated lactate - Indicates tissue hypoxia and transmural injury 1

Important Clinical Caveats

• Normal initial laboratory values do not rule out transmural necrosis - Serial measurements are essential for monitoring disease progression 1
• The kinetics of laboratory data are more useful than single values - Trending electrolytes, pH, and lactate over the first 24-48 hours guides management decisions 1
• Clinical symptoms do not correlate with injury severity - Laboratory and imaging findings are superior to physical examination for predicting outcomes 1, 4

Timing and Follow-Up

Laboratory evaluation should be performed immediately upon presentation and repeated serially during the first 24-48 hours, as caustic injuries can progress during this period 1. Ammonia ingestion specifically requires surveillance over 24-48 hours as superficial hemorrhagic gastritis may worsen 1.