D74.0 ICD-10-CM Code: Congenital methemoglobinemia

D74.0 is the ICD-10-CM diagnosis code for congenital methemoglobinemia. This is a rare inherited blood condition where a person is born with an abnormality in their hemoglobin (the protein that carries oxygen in red blood cells), causing it to form methemoglobin which cannot effectively transport oxygen. This results in a bluish discoloration of the skin and lips, and reduced oxygen delivery to body tissues. D74.0 sits in the ICD-10-CM chapter for diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (d50-d89), within the section covering other disorders of blood and blood-forming organs (d70-d77).

D74.0 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

This is a congenital condition, so it should be coded even if the patient is an adult; verify documentation confirms the condition is present from birth rather than acquired later.