Platelet morphology in Parkinson's disease: an electron microscopic study.

There are no peripheral diagnostic markers for Parkinson's disease (PD). However, recent studies of platelets in PD patients indicate that mitochondrial and monoamine oxidase function may be abnormal. This investigation examines platelets in PD from a morphological standpoint utilizing transmission electron microscopy (EM). Fourteen PD patients (seven treated, seven untreated) and seven age matched controls had platelets separated from other blood components, fixed in a standardized fashion and examined by EM. Platelets (in the activated form because they were collected in glass tubes) were evaluated at magnifications of 15,000x and 40,000x. Abnormalities observed in treated and untreated PD patients included the presence of numerous large intracytoplasmic vacuoles formed from the open canalicular system. Morphometric examination performed at 40,000x magnification indicated that the mean area of vacuoles and the cytoplasmic volume percent of platelets occupied by vacuoles were significantly greater in PD (p < 0.05) than controls. However, differences observed between treated and untreated PD groups suggest that these changes could be caused by the disease or the treatment or both. No abnormalities were found in relation to mitochondria, storage granules and glycogen. From EM assessment, we conclude that platelets in PD are morphologically abnormal.