Therapeutic drug levels

Injury	Disease	Nutrition	Poison

Symptoms	Surgery	Test	Special Topic

Therapeutic drug levels

Definition:

Therapeutic drug level tests are usually performed to look for the presence and the amount of specific drugs in the blood.

text continues below

With most medications, you need a certain level of drug in the blood stream to obtain the desired effect. Some medications are toxic if the level rises too high and are ineffective if the levels are too low. Monitoring serum drug levels enables your health care provider to ensure that your drug levels are within an effective range.

Alternative Names:
Flecainide - serum; Digoxin - serum; Ethosuximide - serum; Disopyramide - serum; Digitoxin - serum; Lidocaine - serum; Kanamycin - serum; Gentamicin - serum; Imipramine - serum; Lithium - serum; Amikacin - serum; Acetaminophen - serum; Aminophylline - serum; TDM; Desipramine - serum; Chloramphenicol - serum; Amitriptyline - serum; Carbamazepine - serum; Methotrexate - serum; Therapeutic drug monitoring; Theophylline - serum; Tobramycin - serum; Valproic acid - serum; Quinidine - serum; Serum drug levels; Salicylate - serum; Propranolol - serum; Phenytoin - serum; Phenobarbital - serum; Procainamide - serum; Primidone - serum; Nortriptyline - serum
How the test is performed:

Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to cause the vein to swell with blood.

A needle is inserted into the vein, and the blood is collected in air-tight vials or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

Infant or young child:

The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

The sample is then taken to the laboratory, where it is evaluated for the particular drug specified by your health care provider.

How to prepare for the test:

Some drug level tests require preparation. Ask your health care provider for preparation information related to the test ordered.

Infants and children:

The preparation you can provide for this test depends on your child's age, previous experience, and level of trust. For general information regarding how you can prepare your child, see the following: