B12 Store Depletion Begins
Liver B12 reserves start to fall when intake or absorption is inadequate.
- 2–5 mg: Typical liver reserve (placeholder reference value)
- Month 0: Depletion onset (placeholder timepoint)
- None: Symptom presence (placeholder status)
- Low intake: Common cause (placeholder example)
Placeholder heading for store depletion mechanism
Placeholder: reserves shrink slowly before any lab or symptom changes appear.
Subclinical Deficiency — No Symptoms Yet
Stores are low but compensatory mechanisms still mask any symptoms.
- ~20%: Store level (placeholder threshold)
- Borderline: Serum B12 (placeholder lab flag)
- Delayed: Symptom onset (placeholder note)
- Labs only: Detectability (placeholder note)
Placeholder heading for subclinical phase
Placeholder: lab markers may shift before any clinical symptom is noticeable.
Hematologic Symptoms — Macrocytic Anemia
Red blood cells enlarge as impaired DNA synthesis disrupts normal division.
- Elevated: MCV (placeholder lab trend)
- ~Month 6–12: Onset window (placeholder timepoint)
- Common: Fatigue (placeholder symptom)
- High: Reversibility (placeholder outlook)
Placeholder heading for macrocytic anemia
Placeholder: enlarged, fragile red cells reduce oxygen-carrying capacity over time.
Neurologic Symptoms — Paresthesia
Peripheral nerve myelin degrades, producing tingling and numbness.
- ~Month 12–24: Onset window (placeholder timepoint)
- Hands/feet: Common site (placeholder location)
- Myelin loss: Mechanism (placeholder note)
- Moderate: Reversibility (placeholder outlook)
Placeholder heading for paresthesia onset
Placeholder: demyelination of peripheral nerves produces early tingling sensations.
Advanced Neurologic Damage — Ataxia
Prolonged deficiency damages spinal cord pathways, impairing coordination.
- ~Month 24–36: Onset window (placeholder timepoint)
- Gait ataxia: Key sign (placeholder symptom)
- Cord damage: Mechanism (placeholder note)
- Low: Reversibility (placeholder outlook)
Placeholder heading for advanced neurologic damage
Placeholder: prolonged deficiency risks irreversible spinal cord degeneration.
Placeholder callout: early treatment before this stage improves recovery odds.