Abstract
In pernicious anemia, mild or moderate thrombocytopenia is widely known, but qualitative platelet defects were scarcely reported.
We have reported two cases of pernicious anemia with abnormal platelet function.
Case 1: 68-year-old man who complained of palpitation and dyspnea on exertion. Laboratory data as follows: Hb 5.5g/dl, RBC 156×104/μl, Ht 19%, Plts. 6.9×104/μl, WBC 3, 000/μl, LDH 3, 508u, Vitamin B12 108pg/ml (N. 460-1, 140), positive Scilling test. Bone marrow aspirates disclosed hyperplasia of megaloblastic erythroid precursors and giant metamyelocytes. Platelet function as follows: Bleeding time (Duke method) 3′30″, Clot retraction 68%, PF-3 availability (TGT method) 11.0″, Platelet retention (Hellem II method) 32%, Platelet aggregation with ADP (1×10-5M)20%, Epinephrine (1×10-4M) 12.7% with lacked secondary aggregation, Collagen (10mcg/ml) 5.1%.
Case 2: 68-year-old woman who was admitted because of paresthesis of fingers and GI bleeding. Hb 4.7g/dl, RBC 118×104/μl, Ht 15%, Plts. 7.3×104/μl, WBC 3, 600/μl, direct bilirubin 2.9mg/dl, LDH 2, 152u, Vitamin B12 148pg/ml, Scilling test was positive. Megaloblasts and giant metamyelocytes were increased in bone marrow aspirates. Platelet function tests as follows: Bleeding time 1′, Clot retraction 60%, PF-3 availability 10.8″, Platelet retention 73%, Platelet aggregation with ADP 54%, Epinephrine 51%, Collagen 49%.
Impaired platelet function returned to normal after parenteral administration of Vitamin B12 in both cases, and platelet aggregation was accelerated in one case.
Mechanisms of abnormal platelet function in pernicious anemia are still unknown, but we speculate that qualitative platelet defects may be associated with abnormal constituents of lipid in platelets of Vitamin B12 deficiency.
