Biomaterial Database

Methotrexate interferes with determinations of conjugated bilirubin with the Kodak Ektachem 400. 1986

S Swanson, and T E Mifflin, and J C Boyd

Immediately after intravenous infusion of a high dose (concentration in serum greater than 1000 mumol/L) of methotrexate, the apparent conjugated bilirubin (Bc) concentrations in serum of two osteosarcoma patients, as measured by the Kodak Ektachem 400 analyzer, were greater than the corresponding total bilirubin concentrations, but decreased as the concentrations of methotrexate in serum decreased. In an interference study we found that methotrexate added to sera containing a wide range of basal Bc concentrations increased the measured Bc concentration in a linear and dose-related fashion. Methotrexate also interfered negatively with measurements of unconjugated bilirubin (Bu). The source of the interference appears to be an overlap in the absorption spectrum of methotrexate with Bc and Bu at 400 nm.

UI	MeSH Term	Description	Entries
D008727	Methotrexate	An antineoplastic antimetabolite with immunosuppressant properties. It is an inhibitor of TETRAHYDROFOLATE DEHYDROGENASE and prevents the formation of tetrahydrofolate, necessary for synthesis of thymidylate, an essential component of DNA.	Amethopterin,Methotrexate Hydrate,Methotrexate Sodium,Methotrexate, (D)-Isomer,Methotrexate, (DL)-Isomer,Methotrexate, Dicesium Salt,Methotrexate, Disodium Salt,Methotrexate, Sodium Salt,Mexate,Dicesium Salt Methotrexate,Hydrate, Methotrexate,Sodium, Methotrexate
D005189	False Positive Reactions	Positive test results in subjects who do not possess the attribute for which the test is conducted. The labeling of healthy persons as diseased when screening in the detection of disease. (Last, A Dictionary of Epidemiology, 2d ed)	False Positive Reaction,Positive Reaction, False,Positive Reactions, False,Reaction, False Positive,Reactions, False Positive
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D001322	Autoanalysis	Method of analyzing chemicals using automation.	Autoanalyses
D001663	Bilirubin	A bile pigment that is a degradation product of HEME.	Bilirubin IX alpha,Bilirubin, (15E)-Isomer,Bilirubin, (4E)-Isomer,Bilirubin, (4E,15E)-Isomer,Bilirubin, Calcium Salt,Bilirubin, Disodium Salt,Bilirubin, Monosodium Salt,Calcium Bilirubinate,Hematoidin,delta-Bilirubin,Bilirubinate, Calcium,Calcium Salt Bilirubin,Disodium Salt Bilirubin,Monosodium Salt Bilirubin,Salt Bilirubin, Calcium,delta Bilirubin
D012516	Osteosarcoma	A sarcoma originating in bone-forming cells, affecting the ends of long bones. It is the most common and most malignant of sarcomas of the bones, and occurs chiefly among 10- to 25-year-old youths. (From Stedman, 25th ed)	Sarcoma, Osteogenic,Osteogenic Sarcoma,Osteosarcoma Tumor,Osteogenic Sarcomas,Osteosarcoma Tumors,Osteosarcomas,Sarcomas, Osteogenic,Tumor, Osteosarcoma,Tumors, Osteosarcoma
D013053	Spectrophotometry	The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.