Metathesaurus HCPCS Hierarchical Terms (MTHHH) is produced by the U.S. National Library of Medicine (NLM).
MTHHH is based on information found in the Healthcare Common Procedure Coding System (HCPCS) codebook published by the American Medical Association (AMA).
MTHHH terms were created to establish a hierarchy for HCPCS codes. For more information about HCPCS, see the HCPCS source synopsis.
MTHHH provides a hierarchy for HCPCS codes based on the hierarchy found in the HCPCS codebook.
Metathesaurus Update Frequency
MTHHH is updated annually in the Metathesaurus, in conjunction with HCPCS.