Table 4.
Diagnostic discrepancies between HemosIL AcuStar ADAMTS13 activity assay and in‐house FRETS‐VWF73 assessing < 10 IU/dL ADAMTS13 activity in 15 plasma samples
| Patient | ADAMTS13 activity by in‐house FRETS‐VWF73 assay (IU/dL) | ADAMTS13 activity by HemosIL AcuStar assay (IU/dL) | Anti‐ADAMTS13 IgG titers (ELISA, U/mL) (N < 15 U/mL) | Clinical context and complementary ADAMTS13 investigation |
|---|---|---|---|---|
| TMA | 11 | 5.1 | 9 | Pregnancy and systemic lupus erythematosus |
| aTTP – acute phase | <10 | 12 | 11 | Liver transplantation |
| aTTP – acute phase | <5 | 17 | 24 | Hepatitis B, hepatocellular carcinoma, and kidney transplantation |
| aTTP – relapse | <10 | 13 | 7 | None |
| Congenital TTP (USS) | <5 | 13 | 10 | Exon 3: c.262G > C (p.Val88Leu) Exon 24: c.3178C > T (p.Arg1060Trp) |
| aTTP – acute phase | <5 | 22 | 5 | Pregnancy |
| aTTP – acute phase | <10 | 17 | 6 | Pregnancy |
| aTTP – acute phase | <10 | 26 | 10 | None |
| aTTP – relapse | <5 | 29 | 12 | None |
| aTTP – acute phase | <10 | 16 | 16 | None |
| TMA a (icteric and lactescent sample) | <10 | 11 | 1 | Hematopoietic stem cell transplantation and Escherichia coli O157:H7 infection |
| aTTP – relapse | <5 | 13 | 7 | None |
| aTTP – relapse | <5 | 11 | 27 | Pregnancy |
| TMA* | <5 | 28 | 21 | Tuberculosis |
| TMA a (icteric sample) | <10 | 11 | 2 | Heart failure with congestive hepatopathy |
Abbreviations: aTTP, acquired thrombotic thrombocytopenic purpura, TMA, thrombotic microangiopathy; TTP, thrombotic thrombocytopenic purpura; USS, Upshaw‐Schulman syndrome.
a
Although ADAMTS13 activity was < 10 IU/dL with FRETS‐VWF73 assay, clinical context led to a diagnosis of TMA with a specific severe functional deficiency in ADAMTS13, that is, TTP‐like syndrome.