Diagnostic Criteria and Clinical Characteristics
Definitions and Epidemiology
Severe HHcy is generally restricted to individuals with inherited disorders of Hcy metabolism, is defined as tHcy greater than 100 mmol/L. The most recognized etiology of severe HHcy is CBS deficiency, causing classic homocystinuria. In 1975, the first description of CBS deficiency and its association with thrombophilia leading to early stroke and heart attack in untreated patients led the medical community to suspect milder elevations of Hcy as a contributing factor to atherosclerosis pathogenesis. In the general population, this suspicion has been corroborated through large epidemiologic trials, although Hcy is not currently viewed as an important risk factor.
Mild HHcy is variably defined as tHcy of 12 to 30 mmol/L, and in some literature as 15 to 30 mmol/L while moderate HHcy is defined as tHcy 30 to 100 mmol/L. Mild-to-moderate HHcy of multifactorial etiology appears ...