ClaussTest

ClaussTest is a laboratory assay used to determine the functional fibrinogen concentration in human plasma. It is commonly referred to as the Clauss fibrinogen assay and is based on the Clauss method. The test measures the time required for a clot to form after adding a high concentration of thrombin to platelet-poor plasma. The clotting time is inversely related to the functional fibrinogen level, and results are quantified by comparing the observed time to a calibration curve derived from reference plasmas with known fibrinogen concentrations. Results are typically reported in milligrams per deciliter (mg/dL) or grams per liter (g/L).

Procedure and interpretation are standardized within clinical laboratories but can vary by platform. Plasma is collected with citrate anticoagulant, and a thrombin reagent is added to initiate clotting. The instrument records the clotting time, which is mapped to a fibrinogen concentration using a preestablished standard curve. Clinicians use ClaussTest results to assess bleeding risk and to diagnose fibrinogen disorders. It is commonly employed in evaluating hypofibrinogenemia and dysfibrinogenemia, monitoring replacement therapy, and guiding perioperative management.

Limitations and considerations include sensitivity to reagent composition and assay conditions, which can affect comparability between laboratories. The test can be influenced by circulating anticoagulants such as heparin, lupus anticoagulant, or severe dysfibrinogenemia. Standardization remains a concern across different platforms, so results should be interpreted using local reference ranges and in the context of other coagulation tests.

See also: Clauss fibrinogen assay, fibrinogen measurement, coagulation tests.