Diagnosis and Management of Pernicious Anemia in Patients Over 60 with Essential Thrombocythemia

High-Risk Clinical Scenarios Requiring Immediate Suspicion

The American Diabetes Association recommends suspecting pernicious anemia in patients over 60 with essential thrombocythemia and low B12 levels who have neurological symptoms, macrocytic anemia, or a personal/family history of autoimmune disease, particularly type 1 diabetes, autoimmune thyroid disease, or vitiligo 1, 2, 3
Type 1 diabetes patients have the highest risk of pernicious anemia, with pernicious anemia being among the most common comorbid autoimmune conditions alongside thyroid disease and celiac disease 1, 2, 3
Autoimmune thyroid disease strongly associates with pernicious anemia, with B12 deficiency prevalence ranging from 28-68% in this population 4

The American College of Physicians recommends measuring serum total B12 first, with a cost of £2 and rapid turnaround, and if the level is <180 pg/mL, confirming deficiency and proceeding to etiology testing 4
For indeterminate B12 levels (180-350 pg/mL), measuring methylmalonic acid (MMA) can identify functional deficiency, with a sensitivity of 98.4% 4

The European LeukemiaNet recommends considering the risk of medication-related B12 deficiency in patients with essential thrombocythemia, particularly those taking hydroxyurea, which can cause macrocytosis independent of B12 deficiency 5
Long-term cytostatic medications, including hydroxyurea, may produce macrocytic anemia, highlighting the need for regular B12 monitoring 6, 5

The National Institute for Health and Care Excellence recommends beginning intramuscular B12 immediately if neurological symptoms are present, even before antibody results return, as delays can result in irreversible spinal cord damage 7

Motor impairments, including gait disturbances, muscle stiffness, and slowed movements, occur due to neurological involvement in patients with pernicious anemia, particularly those with gastrointestinal disorders or autoimmune conditions 8
Cognitive slowing, including brain fog, difficulty concentrating, and mental fatigue, manifest as slow speech and processing in patients with pernicious anemia 8

Older adults with gastrointestinal disorders, such as celiac disease, inflammatory bowel disease, or history of gastric surgery, are at high risk of developing pernicious anemia due to impaired B12 absorption 9

Additional investigations for fatigue in patients with pernicious anemia should include iron studies, thyroid function tests, vitamin D levels, electrolytes, and inflammatory markers, such as ESR and CRP 8, 9, 10, 11

The American Gastroenterological Association recommends immediate laboratory testing, including complete blood count, serum B12 level, and methylmalonic acid, to confirm diagnosis and proceed to etiology testing in patients with suspected pernicious anemia 9, 10, 11