Clotted blood tube (Serum gel separator clot activator tube)

Minimum blood volume: 5 mL

Paediatric clotted blood tube

Number of vials: 2

Minimum blood volume: 1.6 mL

Toxic level:

at 24 Hr > 5.0 µmol/L

at 48 Hr > 0.5 µmol/L

at 72 Hr > 0.1 µmol/L

(Source: from manufacturer's kit insert)

Monitoring levels of methotrexate to ensure appropriate therapy.

Methotrexate is an antineoplastic drug used solely or in combination with other antineoplastic drugs for the treatment of leukemia and other diseases.

Relatively low doses of methotrexate (approximately 7.5 - 25 mg/week) have been used in the treatment of nonmalignant diseases such as severe psoriasis, asthma, rheumatoid arthritis, sarcoidosis, and transplantation therapy.

Intermediate to high doses of methotrexate (approximately 35 mg/m² - 12 g/m²) with leucovorin (citrovorum-factor) rescue have been used with favourable results in the treatment of osteogenic sarcoma, leukemia, non-Hodgkin's lymphoma, lung and breast cancer.

Sampling time of methotrexate will be dependent on dose, duration of infusion, and clinical status of the patient.

Following a 4 - 6 Hr intravenous methotrexate infusion with dosages ranging from 50 mg/m²  - 15 g/m², a patient with a 24 Hr serum concentration of greater than 5 - 10 µmol/L, a 48 Hr level greater than 0.5 - 1.0 µmol/L, and a 72 Hr level greater than 0.2 µmol/L is at an increased risk of toxicity if conventional low-dose leucovorin rescue is given.