Haemostasis reagent solutions

When suspecting primary haemostatic disorders in a patient with bleeding symptoms and thrombocytopenia and von Willebrand disease (VWD) have been excluded, it is currently recommended to carry out laboratory investigations of platelet function. [1] The assessment of platelet aggregation provides valuable information in order to diagnose inherited platelet disorders (thrombasthenia, Bernard-Soulier syndrome, etc.) or acquired platelet function defects. Platelet aggregation tests can also be performed to monitor and evaluate the effectiveness of antiplatelet medication, which is often performed in specialised labs.  

Platelet aggregation testing uses light transmission aggregometry (LTA), which is considered as the gold standard for testing platelet function. LTA measures the transmission of light through a sample of platelets in suspension (platelet-rich plasma, PRP), which increases when platelets are aggregated by an agonist. [1]

ADP, epinephrine, collagen, arachidonic acid and ristocetin are the recommended agonists to investigate platelet function. [2] Different agonists can be used, according to the clinical status of the patient.

Both automated and semi-automated assays are available to assess platelet function, however, even though semi-automated assays are more accessible, they can be labour-intensive and assay standardisation is a challenge.

Automated and standardised measurements of these agonists can be achieved as easily as other routine tests by utilising Sysmex’s Revohem platelet aggregation reagents together with the automated platelet aggregation function integrated in Sysmex CS-5100, CS-2400/2500 and CS-2000i/2100i analysers.

For more information on the Revohem reagents, please go to the document slider and download our ‘Automated platelet aggregation testing’ flyer, or contact your local Sysmex representative.

Thrombosis management (DOACS)

Heparin and warfarin have been extensively used over the past half century for thrombosis management. However, their highly variable dose responses and need for close laboratory monitoring has driven the search for new anticoagulant drugs with more predictable effects, eliminating the need for laboratory monitoring and frequent individual patient dosage adjustments. Several new direct oral anticoagulants (DOACs) have been developed with the following advantages: oral administration with predictable pharmacokinetics and dose response, wide therapeutic window, shorter half-life, little interference with food and other drugs, and no need for routine monitoring. The DOACs are prescribed for many preventive or curative thromboembolic indications, including the prevention of stroke in patients with non-valvular atrial fibrillation – where need is increasing with the aging population.

DOACs can be classified into two types: direct factor Xa inhibitors (DiXaIs) such as Rivaroxaban, Apixaban and Edoxaban, and direct thrombin inhibitors (DTIs) such as Dabigatran. The heparins and their analogues are catalytic inhibitors, which require the presence of antithrombin (AT) for their activity while DOACs directly inhibit target coagulation serine esterase (thrombin for DTIs or factor Xa for DiXaIs).

The major difference between DOACs and classic anticoagulants in relation to monitoring are:

1. Unlike heparin and its analogues, DOACs do not require regular monitoring, unless in specific patients and under certain clinical circumstances such as: [3, 4]

• unexplained bleeding or recurrent thrombosis despite a correct intake of anticoagulant therapy
• suspected overdose
• admission to intensive care or emergency units (unknown treatment)
• control of bleeding risk before an emergency surgery in individuals anticoagulated with DOACs
• impaired kidney or liver function and/or patients with multiple therapies (long-term treatment)
• to exclude any risk of progressive drug accumulation resulting from a lack of clearance
• to further explore the laboratory findings of unexplained prolonged clotting times

2. The presence of DOACs in plasma affects the results of coagulation tests, routine screening and specialty assays in a variable manner. Liquid chromatography/mass spectrometry (LC/MS) is the reference method used for DOAC concentration measurement in plasma; however, this time-consuming and costly test is available only in highly specialised laboratories. Therefore, it is important to have dedicated tests readily available that are fast, sensitive and quantitatively measure DOAC concentrations in plasma.

Sysmex offers a choice of assays including a complete range of dedicated, assay-specific calibrators and controls, depending on the lab’s needs.

Haemophilia

Haemophilia is a congenital, single coagulation factor deficiency marked by anatomic bleeding, with an incidence of 1 in 10,000 individuals where 85% are factor VIII (FVIII) deficient (haemophilia A) and 14% are factor IX (FIX) deficient (haemophilia B). The disorder may be due to absent or reduced function, or production of an aberrant non-functional molecule of FVIII or FIX. [5] The disorder usually occurs in males and is transmitted by females who carry the abnormality on their X chromosome. However, about one third of all cases is caused by a spontaneous mutation. [6, 7]

Haemophilia is the most frequent haemorrhagic medical condition in children, due to significant haemorrhage risks, which can be life-threatening in the absence of immediate on-demand treatment. Therefore, laboratory assays play an important role in the detection and management of haemophilia.

The care management of haemophiliacs is changing with the emergence of new treatments. The new therapeutic areas make it necessary to review the present biological and clinical monitoring, where chromogenic FVIII and FIX assays have the advantage of a more homogeneous reactivity to the various FVIII or FIX products available. [8] Depending on the situation, assays with different principles should be considered.

Sysmex offers a complete product portfolio for haemophilia diagnosis and management, which ranges from screening to specialty assays including chromogenic FVIII and FIX assays.