Step into the macrocytic anemia caboose and remember the non-megaloblastic causes with the mnemonic My Liver Bleeds a Lot:
• My → Multiple Myeloma (CRAB: Hypercalcemia, Renal failure, Anemia, Bone lesions)
• Liver → Liver disease
• Bleeds → Hemolysis
• A → Alcohol use
• Lot → Hypothyroidism
We start at the front half of the caboose with the non-megaloblastic nun holding a sign with crossed-out “mega” dynamite, marking the absence of hypersegmented neutrophils. The kingpin character raises an alcohol bottle (liver logo) in a toast—reminding us of alcohol as a cause—bumping it into his tuxedo labeled “TSH > 10” for hypothyroidism. Above him, three red balloons drip a drop of blood onto the liver logo, tying in the phrase “My liver bleeds a lot.”
In the back half of the caboose, the B12 sumo baby wears a bandanna labeled “MMA” for methylmalonic acid (elevated in B12 deficiency), reaching up toward a Sistine Chapel ceiling to touch a finger labeled “↑ homocysteine” (seen in both folate and B12 deficiency). These back-half characters remind us that megaloblastic macrocytosis does have hypersegmented neutrophils, and is tied to DNA synthesis problems.
For alcohol-related macrocytosis, we recall Wernicke’s encephalopathy—classic triad:
1. Ophthalmoplegia (eye movement abnormalities)
2. Ataxia (gait disturbance)
3. Confusion (altered mental status)
ED Application:
• In AMS + alcohol use, always give thiamine before glucose to prevent progression to Korsakoff syndrome (confabulation, severe memory deficits).
• Macrocytosis without anemia can be an early alcohol toxicity sign—screen for liver disease, nutritional deficiencies, hypothyroidism, and myeloma.
• Suspect multiple myeloma? Check calcium, renal function, Hgb, and order imaging for bone lesions.
• Non-megaloblastic macrocytosis = treat underlying cause (alcohol cessation, thyroid replacement, liver management, transfusion for hemolysis).
• Megaloblastic macrocytosis = give B12/folate; avoid masking B12 deficiency with folate alone to prevent neurologic damage.