D59.32

HCC Category Mapping

What This Code Means

A rare inherited genetic disorder that causes recurrent episodes of red blood cell destruction and kidney damage.

Coding Tips

• •Confirm family history documentation to support the hereditary nature of the condition
• •Note any genetic testing results or family members affected by the same condition

Clinical Significance

Hereditary hemolytic-uremic syndrome (atypical hemolytic-uremic syndrome) is a rare genetic disorder caused by mutations in complement regulatory proteins (factor H, factor I, membrane cofactor protein, C3, factor B, or thrombomodulin) leading to uncontrolled complement activation on endothelial surfaces. Unlike the more common infection-associated form, hereditary hemolytic-uremic syndrome has a high recurrence rate, progresses to end-stage renal disease in up to 50% of cases, and requires chronic complement inhibitor therapy (eculizumab or ravulizumab) to prevent relapses.

Documentation Requirements

• ✓Document genetic testing results identifying the specific complement pathway mutation when available.
• ✓Record complement levels (C3, C4, factor H, factor I) and functional assays.
• ✓Include family history of hemolytic-uremic syndrome or unexplained renal failure.
• ✓Document the triad findings (microangiopathic hemolytic anemia, thrombocytopenia, acute kidney injury) with supporting laboratory values.
• ✓Record treatment with complement inhibitors, plasma exchange history, and renal function trajectory including any transplant considerations.

Commonly Confused Codes