We had 58 responses to our January 2022 Quick Question. The stem asked, “A patient experiences soft tissue bleeding and poor wound healing. The PT, PTT, and TT are normal. What follow-up profile do you recommend?
- Factors VIII, IX, & XI assays: 10% 
- PAI-1 & D-dimer assays: 0
- Thrombosis risk profile: 2% 
- Platelet count and aggs: 41% 
- Factor XIII assay: 47% 
Thanks to all who participated. For factors VIII, IX, and XI, the PTT is likely to be prolonged. We were looking for factor XIII, whose deficiency is undetected using the PT, PTT, or TT, as the endpoint of these clot-based tests doesn’t measure factor XIII’s crosslinking property. Poor wound healing is a potential clinical clue. Lab scientists employ a fluorogenic or chromogenic substrate factor XIII assay and apply the time-honored, now obsolete, 5.0 molar urea solubility assay.
For thrombocytopenia or a qualitative platelet disorder, the patient is likely to experience systemic bleeding with easy bruising and epistasis. However, the clinical distinction between systemic and anatomic bleeding may not be “binary,” as the symptoms may blend, and surface wounds exhibit prolonged bleeding. Since a platelet disorder may be part of the differential, a platelet count and aggregometry are likely to be included in the factor XIII deficiency workup.
Muszbek L, Katona E, Kerényi A. Assessment of factor XIII. Methods Mol Biol. 2017;1646:277–93. doi: 10.1007/978-1-4939-7196-1_22.