TThe behavior of specificity and PPV depends on whether a higher or lower value indicates disease. Lowering the cutoff means you change the threshold at which a test is considered positive, affecting false positives and true positives differently depending on the test's orientation.
Example:
High Value Positive Test (e.g., blood glucose for diabetes):
Lowering the cutoff increases false positives (non-diabetic people testing positive), decreasing specificity and PPV.
Low Value Positive Test (e.g., serum albumin for malnutrition):
Lowering the cutoff reduces false positives (healthy people testing positive), increasing specificity and PPV.
Source: Other - First Aid Chapter 2.6 Evaluation of Diagnostic Test or see the note Anking image in the extra feild of this card