The conversion or the process of moving of a normal physiology to a disease causing pathology is included in Nidan Panchak.

Nidan Panchak (Five clues to diagnose the disease)

In ayurveda Nidan is the tool to diagnose any particular disease, its origin and trace the evolution. Ayurveda describes the following five tools that help in identifying the diseases and its pathology:

• Hetu (Nidan)
  
• Poorvaroop
  
• Roop
  
• Upshaya
  
• Samprapti