Platelet function and pyrophosphates in osteogenesis imperfecta.

Platelet function and serum pyrophosphate (PPi) levels were measured in 15 osteogenesis imperfecta (OI) patients and their parents. The bleeding time was abnormal in five of the subjects. Platelet adhesion to glass was occasionally abnormal (9 of 30 subjects). Platelet factor 3 (PF3) release was impaired in all patients except one and in one or both parents. Platelet aggregation to ADP was abnormal in most of the subjects. Aggregation to collagen was also frequently defective. Thrombin-induced platelet aggregation was always normal. Serum PPi levels were elevated in 62.5% of the subjects. The increased level of PPi was occasionally related to the defect in release of PF3; however, addition of PPi to normal platelet-rich plasma (PRP) did not alter the PF3 release or ADP aggregation. Thrombin-clotted PRP contributed to the elevated PPi but no more in the subjects than in the controls. Presumed carriers of the gene for OI may have defective platelet function and elevated serum PPi, even though no obvious signs of the disease are apparent.