Pernicious Anemia

Pernicious Anemia:

Deficiency in Vitamin B12, due to deficiency in intrinsic factor; which is produced by the stomach cell. Intrinsic factor is glycoprotein which helps in absorption of vitamin B-12 in terminal ileum. This is an autoimmune disease.

Etiology:

·         Autoimmune: Destruction of gastric parietal cell leads to decrease in production of intrinsic factors. Pernicious anemia may be related to diabetes mellitus type ll, vitiligo or autoimmune thyroid disease.

·         Genetic

·         Others: Veg diet; Gastrectomy;  insufficient pancreatic enzymes; tapeworm infestation; bacterial condition

Pathophysiology:

Two types of auto antibodies are found in pernicious anemia:

1) Intrinsic factor antibodies: type 1; acts against vitamin B12 binding site & type 2; acts against ileal mucosa receptor.

2) Parietal cell antibodies

Sign and symptoms:

It has insidious onset.

- Pallor

- Fatigue

- Dyspnea

- Dizziness

- Tachycardia

- Decrease in cognitive and physical function

- Abdominal bloating

- Loss of appetite

- Weight loss

- Diarrhea

- Peripheral neuropathy

- Paraesthesia (an abnormal sensation)

- Ataxia, forgetfulness, altered mental status

- Palpitation

- Edema

- Urinary retention

- Visual deficits

- Low grade fever, beefy red tongue, blotchy skin pigmentation

- Blotchy skin pigmentation

Work-up:

-  Complete blood count, Serum vitamin B12, Peripheral smear

- MCV would be >=100 fL

- Vitamin B12 would be <200 pg/dl

- Elevated homocysteiene level and methylmalonic acid level

- Detection of intrinsic factor antibodies

- CobaSorb test 

Complication:

-  Neutropenia

- Thrombocytopenia

- Inflammation of tongue (Glossitis)

- Neurological signs: Ataxia, areflexia, and paraesthesia with Romberg’s sign.

Differential diagnosis:

- Increased erythropoiesis

- Hypoplastic anemia

-Myelodysplastic syndrome

- Ileal disease

- Gastrectomy

- Chronic obstructive pulmonary disease

- Drugs

Treatment and Management:

Vitamin B-12 intramural injection 1000mcg every day or alternate day for 1^st week. From next month; weekly followed by monthly.

Oral Vitamin B-12 1000 or 2000 mcg/day. Oral is not recommended for CNS symptoms.

Through treatment, marked increase in reticulocyte count is observed. KEY MANAGEMENT IS REGULAR FOLLOW-UP.

Prognosis:

When treated well, there are good chances of normal life. But if undiagnosed it can even lead to fatal condition.

To know more click on the following link:

Credit: https://www.ncbi.nlm.nih.gov/books/NBK540989/

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