Solution to "A Disoriented, Nauseated Car Wreck Victim"

Robert M. Centor, MD; Karen L. Samples

Disclosures

February 23, 2006

This is the solution to a case we presented recently. You may review the case at http://www.medscape.com/viewarticle/520693.

Solution and Discussion

The patient has an increased anion gap acidosis.

Calculations:

1. Anion gap = 33

2. Delta gap calculation = (observed gap - expected gap) + observed bicarbonate = (33 - 12) + 5 = 26.

Thus, the patient started out with a normal bicarbonate (this excludes an underlying metabolic acidosis or alkalosis).

3. Winter's equation = 1.5 (calculated bicarbonate) + 8 (+ or -) 2 [expected pCO2] = 1.5 (2) + 8 = 11.

This suggests that the hyperventilation is appropriate for the degree of metabolic acidosis.

We use the mnemonic KILU for remembering the differential of anion gap acidosis:

Ketoacidoses (diabetic, alcoholic, starvation)

Ingestions (salicylates, ethylene glycol, methanol – and, less commonly, iron and isoniazid)

Lactic acidosis

Uremia

Anion gaps > 25 occur primarily with diabetic ketoacidosis, lactic acidosis, ethylene glycol, and methanol.

In consideration of the stable vital signs and normal blood sugar, the physicians appropriately considered an ingestion. They ordered a serum osmolality.

Lab values:

Serum osmolality = 395

Calculated osmolality = 289

Thus, osmolal gap = 96

This supports a likely ingestion with either ethylene glycol or methanol.

UA showed calcium oxalate crystals.

The positive calcium oxalate crystals made the likely diagnosis ethylene glycol toxicity, which laboratory data confirmed. Laboratory testing excluded lactic acidosis, methanol toxicity, salicylate toxicity, and ketoacidosis.

After the patient's mental status returned to normal, he admitted to drinking "moonshine" liquor in large amounts. We assume (but cannot be certain) that the moonshine had ethylene glycol added (to provide a sweet taste).

Treatment: The patient received fomepizole (an alcohol dehydrogenase inhibitor) and dialysis. He subsequently developed nonoliguric acute renal failure, which resolved over 1 week, at which time he was discharged.

Read and participate in the discussion of this case at http://boards.medscape.com/forums?50@58.fOQtaxEdgj6.0@.29d4e665/2 and watch for another new case soon.

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