A 59-year-old male was diagnosed with mild macrocytic anemia during

a health examination

without any specific complaints. Complete blood count revealed macrocytic anisocytosis

and microscopic examination showed red blood cell size variation and neutrophilic hypersegmentation. Follow-up complete blood count and blood smear microscopy

combined with complete biochemical panel (elevated bilirubin

lactate dehydrogenase

and homocysteine) and anemia panel (decreased vitamin B

12

normal folate and ferritin)

confirmed the diagnosis of vitamin B

12

deficiency megaloblastic anemia based on the diagnostic criteria for megaloblastic anemia. Targeted vitamin B

12

supplementation was administered to correct hematopoietic substrate deficiency and correct cellular DNA synthesis disorders. After standardized treatment

the patient's hematopoietic function gradually recovered

with complete blood count

biochemical

and anemia panel indicators all returning to normal. No anemia-related neurological or digestive symptoms were observed

and the clinical outcome was favorable.