Back in 1849, Thomas Addison termed a condition as a "deadly" form of anaemia and this term came into use because, before the availability of treatment, the disease was often fatal.
So, what is this deadly form of anaemia?
Imagine your body as a bustling city, with Vitamin B12 as one of its most valuable resources. It's essential for the city's operations, but there's a problem - the city's transport system is broken. The trucks that usually carry B12, known as intrinsic factors, are missing. This is the crux of Pernicious Anaemia, an autoimmune condition where your body, the city, is unable to absorb B12 due to a lack of these intrinsic factor trucks.
✏️ Intrinsic factors or IF are glycoproteins produced by the parietal cells (oxyntic cells) located at the gastric body and fundus.
✏️ Intrinsic factor plays a crucial role in the transportation and absorption of the vital micronutrient vitamin B12 (cobalamin, Cbl) by the terminal ileum
What happens then?
Now, what happens when the city runs low on this precious resource? The citizens start to feel the effects. They're fatigued, their skin turns pale, their tongues become inflamed (glossitis), and they even start to experience neurological symptoms due to a condition called subacute combined degeneration of the spinal cord. These are the clinical features of our city in crisis.
✏️ Subacute combined degeneration (SCD):
Demyelination of the spinal cord caused by Cbl deficiency:
Dorsal column demyelination: loss of sense of vibration, proprioception (ataxia), and stereognosis
Lateral corticospinal tract demyelination: motor deficit and hyperreflexia
✏️ Hematological manifestations:
Megaloblastic anaemia: lightheadedness, palpitations, weakness, and anginal pain
Thrombocytopenia: purpura
✏️ Neuropsychiatric manifestations:
Dementia
Polyneuritis
Positive Babinski reflex
✏️ GIT manifestations:
Glossitis: shiny, smooth tongue caused by the atrophy of the lingual papillae
✏️ Cardiovascular manifestation:
Congestive heart failure caused by severe anaemia
Coronary artery disease, limb ischemia or cerebrovascular events, secondary to hyperhomocysteinemia
How do we know for sure that it's Pernicious Anaemia?
Our city's scientists (doctors) run tests and find low levels of B12 in the city's resource stores (serum), signs of macrocytic anaemia, and the presence of antibodies against intrinsic factors and gastric parietal cells. These are the telltale signs of Pernicious Anaemia.
🧪 Let's test it
Anti-intrinsic factor antibody (Specific to pernicious anaemia)
Anti-parietal cells antibody
Full blood count (FBC): Mean corpuscular volume (MCV) greater than 100 fL
Peripheral blood smear: Pancytopenia, oval macrocytosis, and hypersegmented neutrophils (at least five lobes) in case of megaloblastic anaemia.
Bone marrow examination: Megaloblastic hyperplasia in megaloblastic anaemia.
Serum B12 level: A level below 150 pg/mL is diagnostic
The solution?
Lifelong shipments of B12, usually in the form of hydroxocobalamin injections. This ensures the city never runs out of its valuable resource again. However, the city isn't out of the woods yet. It's at an increased risk of dangerous invaders - gastric carcinoma and gastric carcinoid tumours. These are potential complications of Pernicious Anaemia.
📚 Take home notes:
Consider pernicious anaemia as one of the possibilities when dealing with vitamin B12 deficiency (macrocytosis and megaloblastic anaemia)
Look out for systemic manifestations i.e 🧠, ❤️, 🩸and 🤮
Investigate quickly without delay!
Lifelong treatment with vitamin B12 replenishment ---> Injections!
Monitor for other associated conditions like gastric carcinoma and gastric carcinoids