Drug-Induced Liver Injury Profile

Serum (preferred) or plasma and whole blood or plasma

Serum or plasma: 1 mL

PT with INR blood: 2.7 mL size tube filled to 90% capacity or 1.8 mL size tube

Serum or plasma: 0.7 mL (Note: This volume does not allow for repeat testing.)

PT with INR: 90% of full draw

Red-top tube, gel-barrier tube or green-top (lithium heparin) tube; do not use oxalate, EDTA or citrate plasma and blue-top (sodium citrate) tube; do not open tube unless plasma is to be frozen.

This test is used for initial laboratory assessment of drug, herbal and dietary supplement-induced liver injury.

The PT test may not be sensitive to slight deficiencies of single factors. Heparin can extend the PT. Lupus anticoagulants may affect prothrombin time producing results that do not accurately reflect the true level of anticoagulation. The PT (and aPTT) results can be extended in patients receiving antithrombin anticoagulants such as hirudin and argatroban. These patients can be monitored for warfarin effectiveness with a chromogenic factor X assay, which is not affected by lupus anticoagulant or thrombin inhibitors.

See individual tests.

Clinically significant biochemical evidence of drug-induced liver injury (DILI) is typically defined as meeting one of the following criteria:

• Serum AST or ALT >5x Upper Limit of Normal (ULN), or ALP > 2x ULN (or pretreatment baseline is abnormal) on two occasions;

• Total serum bilirubin >2.5mg/dL along with elevated AST, ALT, or ALP level; or

• INR >1.5 with elevated AST, ALT, or ALP.

These patterns can be more precisely and quantitatively expressed though the R value at presentation when:

• R value ≥ 5.0 identifies hepatocellular liver injury

• R value 2.1- 4.9 identifies mixed liver injury

• R value ≤ 2.0 identifies cholestatic liver injury

When liver injury falls into hepatocellular or mixed categories, it may be important to exclude other causes of liver injury.¹