“H” and “HH” appear to be codes used in the Public Health Information Network Vocabulary Access and Distribution System (PHIN VADS) and in the international Health Level 7 (HL7) medical software standard. There does not seem to be much information available online about these codes, especially in Japanese, because apparently they are for internal use by specialists and are rarely shown to patients.

According to https://www.hl7.org/fhir/v3/ObservationInterpretation/cs.htm... in HL7 "HH" is a "code" that should display the message "Critical high" on a machine, and it has the following definition: "The result for a quantitative observation is above a reference level at which immediate action should be considered for patient safety (as defined for the respective test procedure). Synonym: Above upper panic limits."

Analyzing “上限値異常値超” piece by piece, “上限値” means “upper limit (value)”, “異常値” means “abnormal value”, and “超” means “exceeds” or “more than”, so literally “上限値異常値超” would mean “exceeds abnormal value (of) upper limit (value)”. Since that meaning sounds a lot like the meaning of “above a reference level at which immediate action should be considered for patient safety”, I would assume that “上限値異常値超” is meant to be the Japanese concept name for what PHIN VADS and HL7 give as “critical high” or “above upper panic limit”. It therefore ought to be safe to translate “上限値異常値超” as “above upper panic limit”.