MPV - Mean Platelet Volume. Measures the average size of platelets and reflects their function. May be elevated due to increased platelet production, which is often caused by loss or destruction of existing platelets. Elevated MPV can be associated with vascular disease and mortality, some cancers, type 2 diabetes, and Hashimoto's thyroiditis. MPV may be decreased due to conditions associated with under-production of platelets such as aplastic anaemia or cytotoxic drug therapy.