What is the management for thyroxine (T4) tablet poisoning?

Management of Thyroxine Tablet Poisoning

The management of thyroxine tablet poisoning should focus on gastrointestinal decontamination, symptomatic treatment, and supportive care with specific interventions to counteract thyroid hormone effects.

Initial Assessment and Management

• For acute massive overdose, perform gastric emptying via emesis or gastric lavage if the patient presents within hours of ingestion and has no contraindications (seizures, coma, or loss of gag reflex) 1
• Administer activated charcoal or cholestyramine to decrease gastrointestinal absorption of thyroxine 1, 2
• Assess vital signs with particular attention to heart rate, blood pressure, respiratory rate, and temperature 3
• Obtain baseline thyroid function tests (TSH, free T4, free T3) to establish severity of poisoning 3, 4

Symptomatic Treatment

• Control increased sympathetic activity with beta-blockers (e.g., propranolol), provided there are no medical contraindications to their use 1, 3
• For severe symptoms of thyrotoxicosis:
  • Administer large doses of antithyroid drugs (methimazole or propylthiouracil) followed by large doses of iodine to inhibit synthesis and release of thyroid hormones 1
  • Consider glucocorticoids to inhibit the conversion of T4 to T3 1
• Provide respiratory support as needed 1
• Control congestive heart failure and arrhythmias if they develop 1, 4
• Manage fever, hypoglycemia, and fluid loss as necessary 1

Severe Cases

• For patients with continued clinical deterioration despite conventional therapy, consider advanced interventions such as plasmapheresis, charcoal hemoperfusion, or exchange transfusion 1
• Hemodialysis may be considered in massive overdoses, although it removes very little drug due to high protein binding of T4 1, 3
• Monitor for delayed onset of symptoms, as thyrotoxicosis from levothyroxine overdose may not appear until several days after ingestion 4, 5

Monitoring

• Continuously monitor vital signs, particularly heart rate and blood pressure 3, 4
• Check thyroid function tests (TSH, free T4, free T3) regularly to track the course of toxicity 3, 6
• Monitor for at least 48-72 hours post-ingestion in significant overdoses, as symptoms may be delayed 6, 5
• Consider outpatient follow-up for 14 days after significant ingestions 6

Special Considerations

• Pediatric patients may have a more benign course than adults but still require monitoring for delayed symptoms 6, 5
• Adults often exhibit more severe symptoms after overdose due to complex medical history and comorbidities 3
• Symptoms may persist for 1-2 weeks in severe cases 4

Clinical Course and Prognosis

• Most patients with thyroxine overdose have a favorable outcome with appropriate supportive care 3, 2
• Weight loss may be significant during the recovery period 4
• Complete recovery of thyroid function to pre-ingestion levels typically occurs within 4 weeks 3