What are the different types of protein S deficiency?

The classification of PS deficiency is as follows:

Type 1: Low Protein S Ag Total, Low Protein S Ag Free, Low Protein S Activity
Type II: Normal PS Ag Total, Normal PS Ag Free, Low PS Activity
Type III: Normal PS Ag Total, Low PS Ag Free, Low PS Activity

Type II deficiency seems to be quite rare. Acquired PS is also possible, such as with liver disease, DIC, IBD, and APS. Some research suggests that free PS rather than total PS should be measured in the diagnosis of PS deficiency.