Transient false-positive urine human chorionic gonadotropin in septic shock

Area of Science:

• Clinical Chemistry
• Immunodiagnostics
• Emergency Medicine

Background:

• Point-of-care urine human chorionic gonadotropin (hCG) tests are widely used for rapid pregnancy diagnosis.
• These tests utilize enzyme-linked immunosorbent assay (ELISA) technology with monoclonal antibodies.
• Previous reports indicate potential interference in various disease states leading to false-positive results.

Observation:

• A nonpregnant female with septic shock and severe colitis presented with three sequential positive urine hCG tests.
• Quantitative serum hCG analysis was negative, contradicting the urine test results.
• Urine test results normalized to negative within 48 hours, suggesting transient interferent presence.

Findings:

• The case demonstrates a false-positive urine hCG result in a critically ill patient.
• The interferent may be a molecule from the host's inflammatory response or bacterial synthesis.
• The transient nature of the interferent suggests a temporary alteration in urine composition.

Implications:

• Clinicians must be aware of the limitations and potential interferences with urine hCG testing.
• A low threshold for early serum hCG testing is crucial for accurate diagnosis in ambiguous cases.
• Understanding interferents is vital for reliable point-of-care diagnostic test interpretation.