Eltrombopag interference in routine chemistry testing.

BACKGROUND: High doses of Eltrombopag have been previously reported to cause bilirubin interference. Following receipt of a sample from a patient receiving high-dose Eltrombopag therapy, the laboratory decided to investigate the effect of this drug on routine chemistry testing.

METHODS: Interference studies were performed by spiking Eltrombopag into aliquots of a serum pool to give concentrations ranging from 0 to 500 µg/mL. The following analytes, namely albumin, alkaline phosphatase, alanine transaminase, aspartate transaminase, Urea, total calcium, cholesterol, triglycerides, glucose, high-density lipoprotein cholesterol, iron, magnesium, inorganic phosphate, creatinine, bicarbonate, transferrin, ferritin, electrolytes, total and direct bilirubin and serum indices (hemolysis, icterus and lipaemia) were then measured on the Roche Cobas 6000 chemistry analyzer (Roche, Indianapolis, USA).

RESULTS: Eltrombopag interference (>10% change of the baseline value) was observed for total cholesterol, triglycerides, inorganic phosphate and high-density lipoprotein cholesterol. Clinical significant interference was observed for total cholesterol, inorganic phosphate and high-density lipoprotein cholesterol

CONCLUSIONS: Presence of high Eltrombopag concentrations in blood samples has been demonstrated to cause interference in the measurement of certain spectrophotometric-based assays on the Roche Cobas 6000 analyzer.