Laboratory evaluation of patients presenting with an acute TMA
| Tests . | Indication . | Utility . |
|---|---|---|
| CBC, reticulocyte count; LDH; bilirubin (total, indirect), haptoglobin; blood smear | All patients | Establish diagnosis of TMA with thrombocytopenia, hemolytic anemia, and schistocytes. |
| PT, aPTT, D-dimer, fibrinogen | All patients | Rule out disseminated intravascular coagulation. |
| ALT, AST; creatinine, urinalysis, cardiac troponin, ECG | All patients | Assess organ damage. |
| ADAMTS13 activity | All patients | CONFIRM or rule out TTP. |
| ADAMTS13 inhibitor and antibody | If ADAMTS13 < 20% | Confirm immune vs congenital TTP. Consider ADAMTS13 sequencing if ADAMTS13 inhibitor and antibody tests are persistently negative and ADAMTS13 activity remains less than 20% in remission. |
| Stool culture/Shiga toxin | Recent diarrheal illness | Confirm STEC-HUS |
| Vitamin B12, MMA, homocysteine | Pancytopenia, suggestive blood smear (extreme pleomorphism, macro-ovalocytes, hypersegmented neutrophils | Assess for severe vitamin B12 deficiency that can present as “pseudo-TTP” |
| Autoimmune screening (eg, antiphospholipid antibodies, lupus anticoagulant, ANA) | aHUS with autoimmune history | Identify secondary TMA vs aHUS trigger |
| Infectious workup (eg, cultures, HIV) | Based on symptoms and history | Identify secondary TMA vs aHUS trigger |
| Renal biopsy | If cause of renal injury is unclear | Can distinguish TMA from other cases of renal injury and thrombocytopenia (eg, tubular necrosis from sepsis or medications, posttransplant rejection) but cannot distinguish specific etiology of renal TMA. |
| Tests . | Indication . | Utility . |
|---|---|---|
| CBC, reticulocyte count; LDH; bilirubin (total, indirect), haptoglobin; blood smear | All patients | Establish diagnosis of TMA with thrombocytopenia, hemolytic anemia, and schistocytes. |
| PT, aPTT, D-dimer, fibrinogen | All patients | Rule out disseminated intravascular coagulation. |
| ALT, AST; creatinine, urinalysis, cardiac troponin, ECG | All patients | Assess organ damage. |
| ADAMTS13 activity | All patients | CONFIRM or rule out TTP. |
| ADAMTS13 inhibitor and antibody | If ADAMTS13 < 20% | Confirm immune vs congenital TTP. Consider ADAMTS13 sequencing if ADAMTS13 inhibitor and antibody tests are persistently negative and ADAMTS13 activity remains less than 20% in remission. |
| Stool culture/Shiga toxin | Recent diarrheal illness | Confirm STEC-HUS |
| Vitamin B12, MMA, homocysteine | Pancytopenia, suggestive blood smear (extreme pleomorphism, macro-ovalocytes, hypersegmented neutrophils | Assess for severe vitamin B12 deficiency that can present as “pseudo-TTP” |
| Autoimmune screening (eg, antiphospholipid antibodies, lupus anticoagulant, ANA) | aHUS with autoimmune history | Identify secondary TMA vs aHUS trigger |
| Infectious workup (eg, cultures, HIV) | Based on symptoms and history | Identify secondary TMA vs aHUS trigger |
| Renal biopsy | If cause of renal injury is unclear | Can distinguish TMA from other cases of renal injury and thrombocytopenia (eg, tubular necrosis from sepsis or medications, posttransplant rejection) but cannot distinguish specific etiology of renal TMA. |
ALT, alanine aminotransferase; ANA, antinuclear antibody; aPTT, activated partial thromboplastin time; AST, aspartate aminotransferase; CBC, complete blood count; ECG, electrocardiogram; MMA, methylmalonic acid; PT, prothrombin time.