Correct!
1. A high anion gap metabolic acidosis
The patient has a metabolic acidosis as evidenced by the low serum bicarbonate. Metabolic acidosis can be separated into normal or high anion gap metabolic acidosis (2). A normal anion gap is less than 11 mEq/L and calculated by the following formula:
Anion gap = Na - (Cl + HCO3).
A normal anion gap acidosis is caused by a loss of bicarbonate usually through the gastrointestinal tract or the kidneys and is often associated with a high chloride. A high anion gap occurs when an acid accumulates. The mnemonic MUDPILES is commonly used to remember the causes of increased anion gap metabolic acidosis (Table 2) (3).
Table 2. Causes of an increased anion gap acidosis.
M — Methanol
U — Uremia (chronic kidney failure)
D — Diabetic ketoacidosis
P — Paracetamol, Propylene glycol (used as an inactive stabilizer in many medications; historically, the "P" also stood for Paraldehyde, though this substance is not commonly used today)
I — Infection, Iron, Isoniazid (which can cause lactic acidosis in overdose), Inborn errors of metabolism (an especially important consideration in pediatric patients)
L — Lactic acidosis
E — Ethylene glycol (Note: Ethanol is sometimes included in this mnemonic as well, although the acidosis caused by ethanol is actually primarily due to the increased production of lactic acid found in such intoxication.)
S — Salicylates
Our patient’s anion gap is elevated [147 – (113 +9)] = 25 mEq. Other laboratory work includes:
The patient is becoming increasingly obtunded.
What should be done at this time? (Click on the correct answer to proceed to the fourth of six pages)