D84.1
Defects in the complement system
Billable FY2026 2025-10-01 → 2026-09-30
Exclusions 12 never code together
D80-D89block
D50-D89chapter
Excludes2
- autoimmune disease (systemic) NOS (M35.9)M35.9
- certain conditions originating in the perinatal period (P00-P96)P00-P96
- complications of pregnancy, childbirth and the puerperium (O00-O9A)O00-O9A
- congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)Q00-Q99
- endocrine, nutritional and metabolic diseases (E00-E88)E00-E88
- human immunodeficiency virus [HIV] disease (B20)B20
- injury, poisoning and certain other consequences of external causes (S00-T88)S00-T88
- neoplasms (C00-D49)C00-D49
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)R00-R94
Excludes1 — never code together. The excluded condition and this one are mutually exclusive.
Excludes2 — not included here, but the patient may have both. Code both when documented.
Instructional notes 4
Index entries leading here 9
- Edema, edematous (infectious) (pitting) (toxic) R60.9
- Angioedema (allergic) (any site) (with urticaria) T78.3
- hereditary D84.1
- Angioneurotic edema (allergic) (any site) (with urticaria) T78.3
- hereditary D84.1
- Bannister's disease T78.3
- hereditary D84.1
- Deficiency, deficient
- C1 esterase inhibitor (C1-INH) D84.1
- Defect, defective Q89.9
- complement system D84.1
- Urticaria L50.9
- Giant
- Quincke's disease or edema T78.3
- hereditary D84.1
Alongside this code 3 same parent — D84
Medications 1
MED-RT files conditions by MeSH, which carves the world differently from ICD-10. These are name matches on this code's description, offered as candidates — not as an assertion that they are this code.
Additional references
AHA Coding Clinic® Licence required
Official coding advice for this code. Published by the American Hospital Association. Not included in this installation.