GOLD MARK (better than MUDPILES): Anion Gap Metabolic Acidosis Mnemonic

The GOLD MARK causes are divided into three major pathophysiologic groups based on the source of the acid production:

1. Alcohols (Toxic Ingestions) → Emergency Toxins

• Glycols → Ethylene glycol (antifreeze) and propylene glycol

• Methanol → Windshield washer fluid, homemade alcohol substitutes

• Why grouped together?

• Common in suicide attempts, accidental ingestions, or chronic alcoholics.

• Key labs: Serum osmolality, anion gap, osmolar gap.

• Imaging: Calcium oxalate crystals on urine microscopy (ethylene glycol).

• Treatment: Fomepizole or ethanol (blocks alcohol dehydrogenase), hemodialysis in severe cases.

2. OTCs & Medication-Related Causes → Common but Easily Missed

• Oxoproline → Chronic acetaminophen (Tylenol) use, often in malnourished patients

• Aspirin → Salicylates, including bismuth subsalicylate (Pepto-Bismol)

• Why grouped together?

• Often overlooked in chronic users or the elderly.

• Key signs: Tachypnea (respiratory alkalosis), tinnitus (aspirin), altered mental status.

• Key labs: Salicylate level, ABG (mixed acid-base disorder).

• Treatment: Alkalinization (sodium bicarb drip), dialysis for severe cases.

3. Metabolic Causes → Endogenous Acid Production

• L-lactate → Type A (ischemia), Type B (mitochondrial dysfunction)

• D-lactate → Short gut syndrome, bacterial overgrowth

• Renal Failure → Uremia, organic acids

• Ketones → Starvation, alcohol, diabetic ketoacidosis (DKA)

• Why grouped together?

• These involve internal production of acids due to organ dysfunction.

• Key labs:

• Lactate level (for sepsis, ischemia).

• BHB (beta-hydroxybutyrate) for DKA.

• BUN/Cr for renal failure.

• Urinalysis (ketones, glucose, uremia markers).

• Treatment:

• Fluids, treat underlying cause (DKA → insulin drip, renal failure → dialysis).

Clinically Important Considerations for EM Physicians

In the ED, when a patient has metabolic acidosis with an elevated anion gap, think:

1. What is the patient’s history?

• Suicide attempt or confusion? → Alcohols, aspirin

• Chronic Tylenol use or malnourished? → Oxoproline

• Sepsis, shock, ischemia? → L-lactate

• Short gut, diarrhea, recent antibiotics? → D-lactate

• Known diabetes, alcoholism, or fasting? → Ketones

• Chronic kidney disease? → Uremia

2. What tests should I order immediately?

• ABG/VBG → Confirms metabolic acidosis.

• Anion gap calculation → Determines if the acidosis is anion gap or non-anion gap.

• Serum osmolality & osmolar gap → Alcohol toxicity (ethylene glycol, methanol).

• Lactate level → Sepsis, ischemia, mitochondrial dysfunction.

• BHB (Beta-hydroxybutyrate) → DKA vs. alcoholic/starvation ketosis.

• Salicylate level & acetaminophen level → Toxic ingestion screening.

• CMP (BUN/Cr, glucose, liver enzymes, electrolytes) → Renal failure, DKA, liver dysfunction.

Takeaway: What’s an Emergency?

• Dialysis Emergencies → Methanol, ethylene glycol, severe aspirin toxicity, uremia.

• Toxin Emergencies → Alcohols (treat with fomepizole), salicylates (alkalinization & dialysis).

• Septic Shock / Tissue Hypoxia → Elevated L-lactate = immediate resuscitation with fluids & source control!

• DKA → Fluids, insulin drip, and monitor for electrolyte shifts (esp. potassium).