Deficient and control plasmas
A deficient plasma is human plasma in which a single coagulation factor is absent or reduced to traces, while the others remain in the normal range. It serves as a reference matrix in one-stage clotting assays: the patient plasma is diluted into the deficient plasma, which supplies every factor except the one under test, so that the clotting time depends only on the factor being measured. In the CABRU catalogue the range comes from Affinity Biologicals — 74 references covering 47 haemostasis factors and proteins — alongside the products of BioMedica Diagnostics.
The three types and what they are for
| Type | References in catalogue | What it contains | Use |
|---|---|---|---|
| Deficient plasma | 44 | One factor absent, the others in the normal range | Substrate for the assay of that factor |
| Inhibitor plasma | 21 | An inhibitor against a factor, at mild, moderate or high titre | Verification of methods that quantify inhibitors |
| Control plasma | 9 | Normal pool, sample with altered values, donor set | Quality control and calibration checks |
How a deficient plasma is made
There are two production routes, and they are not equivalent. Congenitally deficient plasma comes from donors carrying the deficiency: it keeps the physiological composition of plasma, but it is scarce material and availability depends on donors. Immunodepleted plasma is obtained by removing the target factor from a normal pool by immunoaffinity: it is reproducible at scale and available for every factor, at the cost of a manipulation that also touches the rest of the matrix. For both routes the specification stated by manufacturers is normally a residual activity of the target factor below 1%, with the other factors in the normal range: the actual value for a batch should always be read on the certificate of analysis.
Frozen or lyophilised, and the pre-analytical stage
In the catalogue 48 references are frozen and 25 lyophilised; the prevailing format is the 1 ml vial in packs of five, present on 65 references. The frozen form keeps the matrix closer to the original but requires a cold chain, rapid thawing at 37 °C and immediate use, with no refreezing. The lyophilised form travels better, but reconstitution volume and equilibration time must be followed to the letter, because a volume error translates directly into an activity error. Upstream, the pre-analytical handling of the sample matters: sodium citrate at the prescribed ratio, platelet-poor plasma, centrifugation and storage times as the method requires. The use context is described on the Haemostasis and coagulation page; the list of references, with codes and pack sizes, is in the product catalogue.