Disorder: Decrease in red blood cell production due to lack of Vitamin B12.
Cause: Autoimmune attack on intrinsic factor (IF) or stomach cells producing IF.
Role of Intrinsic Factor: Binds to Vitamin B12 to facilitate absorption through the gastrointestinal tract.
Consequence: Insufficient absorption of Vitamin B12 leads to decreased red blood cell production.
Symptoms
Weakness and fatigue
Abdominal discomfort after eating/drinking
Palpitations
Mouth ulcers
Weight loss
Jaundice (yellowing of skin/sclera)
Neurological symptoms due to neuron damage:
Paresthesia (pins and needles sensations)
Spasticity (abnormal muscle tone)
Imbalance
Diagnosis
Based on detailed medical history and clinical evaluation.
Blood Tests:
Complete Blood Count (CBC): Increase in mean corpuscular volume (MCV).
Vitamin B12 levels: Typically low.
Peripheral Smear: May show macro-ovalocytes (large oval-shaped red blood cells) and hyper-segmented neutrophils (white blood cells with multi-lobed nuclei).
Antibody Testing: Detects antibodies against intrinsic factor and gastric cells.
Other blood tests for underlying conditions if suspected.
Treatment
Lifelong Vitamin B12 Supplementation:
Intramuscular injections preferred.
Initial therapy: Daily or every other day injections for the first week.
Subsequent therapy: Weekly injections for 1-2 months.
Maintenance therapy: Monthly injections.
Bypasses gastrointestinal tract, allowing absorption without intrinsic factor.
Recap
Pernicious anemia is an autoimmune disease affecting red blood cell production due to lack of Vitamin B12 absorption.
Symptoms range from fatigue and jaundice to neurologic issues.
Diagnosis includes history, physical exam, and laboratory testing.