17 August 2026
: Case report 
From Sight to Stridor: Recurrent Angioedema in Systemic Lupus Erythematosus Associated With Complement Activation
Challenging differential diagnosis, Management of emergency care, Rare disease, Educational Purpose (only if useful for a systematic review or synthesis)
Seyed Khalafi ABCDEF 1*, Lanna Felde ABCDEF 1DOI: 10.12659/AJCR.953593
Am J Case Rep 2026; 27:e953593
Table 1 Summary of laboratory studies (total of 9 hospitalization days).
| Hospital Day 1 | Hospital Day 4 | Hospital Day 7 | Reference range | |
|---|---|---|---|---|
| White blood cells (× 10/UL) | 7.81 | 5.28 | 7.78 | 4.0–11.0 |
| Hemoglobin (g/dL) | 7.7 | 7.5 | 6.2 | 12.4–17.3 |
| Hematocrit (%) | 24.2 | 23.9 | 18.2 | 37.0–50.0 |
| Platelets (× 10/L) | 112 | 110 | 76 | 150–450 |
| Serum sodium (mmol/L) | 138 | 142 | 137 | 135–145 |
| Serum potassium (mmol/L) | 4.0 | 5.5 | 4.4 | 3.6–5.0 |
| Serum chloride (mmol/L) | 100 | 107 | 102 | 98–109 |
| Serum bicarbonate (mmol/L) | 22 | 18 | 20 | 22–31 |
| Blood urea nitrogen (mg/dL) | 79 | 82 | 98 | 6–23 |
| Serum creatinine (mg/dL) | 6.42 | 6.87 | 6.31 | 0.51–0.95 |
| Lactate dehydrogenase (U/L) | 244 | 301 | 135–214 | |
| Serum iron (mcg/dL) | 38 | 37–145 | ||
| Total iron-binding capacity (mcg/dL) | 156 | 149–491 | ||
| Percent iron saturation (%) | 24 | 16–50 | ||
| Ferritin (ng/mL) | 730 | 13–150 | ||
| C4 complement (mg/dL) | 4 | 10–40 | ||
| C3 complement (mg/dL) | 36 | 90–180 | ||
| Haptoglobin (mg/dL) | 188 | 111 | 16–200 | |
| C-reactive protein (mg/L) | 1.6 | < 5.0 | ||
| C1 esterase inhibitor antigen (mg/dL) | 31 | 36 | 21–38 | |
| C1 esterase inhibitor function (%) | 102 | ≥41% | ||
| C1 esterase functional C4 complement (mg/dL) | 5 | 10–40 | ||
| C1q complement (mg/dL) | 5 | 12–22 | ||
| C1q complement binding (ug Eq/mL) | 7.9 | 0.0–3.9 | ||
| Anti-C1q immunoglobulin G antibody (units) | 35 | 0–19 | ||
| Erythrocyte sedimentation rate (mm/h) | 22 | 1–19 | ||
| Double-stranded DNA antibody titer | ≥1: 640 | None |