Qualifier Hierarchies

• Qualifiers are also arranged in a hierarchical structure


• For example, diagnosis is the broad qualifier, narrower qualifiers dealing with diagnosis include pathology, radiography, radionuclide imaging, and ultrasonography


• The qualifier hierarchies can be found here.

Rule of Three

• If more than one qualifier is needed, repeat the descriptor with the appropriate qualifier


• Generally, no more than three qualifiers should be used with any one descriptor


• Use the qualifier hierarchies to assist in reducing the number of qualifiers


• If going up the hierarchy does not help reduce the number of qualifiers, use the descriptor without any qualifiers

Example

• You have a work discussing the issues related to a deficiency of estrogens and how to analyze how much estrogen is in the blood, cerebrospinal fluid and urine
  
  • Use 650 _2 $a Estrogens $x metabolism
    NOT
    
    • 650 _2 $a Estrogens $x deficiency
      
    • 650 _2 $a Estrogens $x blood
      
    • 650 _2 $a Estrogens $x cerebrospinal fluid
      
    • 650 _2 $a Estrogens $x urine