Question: This week’s Image Challenge is prompted by Dr. David Frost. What condition(s) can be responsible for the laboratory anomaly seen above? (No peeking!)

Answer: This screenshot shows a negative anion gap! This is a pretty rare finding and usually means one of a few esoteric things: paraproteinemia (e.g., Multiple Myeloma), bromide toxicity, lithium toxicity, or my exam favourite…lab error!