Lab Case 229 interpretation

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46 years old male patient presented to emergency department with complaint of lower back pain for last 3 days . He has been self medicating  with paracetamol in last 48 hours and has taken total of 16-24 tablets of 500 mg paracetamol in last 24 hours, and 8 tablets in preceding 24 hours.

He weighs 60 KG and does not have any other past medical history. Patient has been seen by intern and has done some blood tests with the results as followed.

Full blood count, urea electrolytes : normal.

Paracetamol level :        22 mg / L   OR    132 micromol / litre

ALT:                               40  IU

Answers:

  1. Criteria ( adult and children 6 +) for Repeated Supratherapeutic ingestion for paracetamol is :

Ingestion of at least 10 g or 200 mg/ kg ( which ever is lower ) in the last 24 hours period.

Ingestion of at least  6 g or 150 mg / kg ( which ever is lower ) per 24 hours in last 48 hours.

Ingestion of more than  4 g or 100 mg / kg ( which ever is lower ) per 24 hours in last 48 hours or longer in patients with back ground of high risk features i.e.` Liver dysfunction, alcoholism, prolonged fasting etc.

2. Management :

Any Toxicology patients management starts with RRSIDEAD .

Above patient does not appear to have any resuscitation issues.

Risk Assessment: Meets 1st criteria of Repeated supratherapeutic ingestion > taken up to 12 g or 200 mg /kg in last 24 hours. so should get paracetamol and ALT levels ( done by intern). Interpretation of ALT and para levels should be according to chart below.

Bottom Line: If paracetamol level is less than 20 mg/ L or 132 micromol / lit and ALT is less than 50 IU >  No treatment required. Any other results will require NAC infusion. Those on treatment will need Para and ALT levels at 8 hours after first measurement and interpreted as per chart below.

RSI paracetamol Algorithm.

 

3. Further information to help risk assessment in suspected supratherapeutic ingestion includes history of liver failure, alcohol dependence, isoniazid therapy, prolonged fasting or features of liver failure like nausea, abdominal pain pain, vomiting all of which reduce the thresh hold of amount of paracetamol taken.