T70.20XAUnspecified effects of high altitude, initial encounter

T70.20XA is the ICD-10-CM diagnosis code for unspecified effects of high altitude, initial encounter. It belongs to category T70 (effects of air pressure and water pressure), block T66-T78 (other and unspecified effects of external causes) and chapter 19 (injury, poisoning and certain other consequences of external causes). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

The 7th character "A" means initial encounter: use it while the patient is receiving active treatment for the condition.

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 922 (Other Injury, Poisoning and Toxic Effect Diagnoses with MCC, relative weight 1.6238) and DRG 923 (Other Injury, Poisoning and Toxic Effect Diagnoses without MCC, relative weight 0.9973), in MDC 21 (Injuries, Poisonings and Toxic Effects of Drugs), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 993.2 (other and unspecified effects of high altitude).