Test ID: THEO
Theophylline, Serum
NY State Approved 
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Assessing and adjusting dosage for optimal therapeutic level
Assessing toxicity
Method Name A short description of the method used to perform the test
Enzyme-Multiplied Immunoassay Technique (EMIT)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Aminophylline (Theophylline), Serum
Choledyl (Oxtriphylline)
Choledyl
Oxtriphylline (Choledyl)
Oxtriphylline
Slo-Phyllin
Slophylline (Theophylline, Anhydrous)
Slophylline
Somophyllin (Theophylline)
Tedral
Theo-Dur (Theophylline)
Theo-Dur
Theodur
Theophyl
Theophylline, Serum
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Container/Tube: Red top
Specimen Volume: 1 mL
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | Mild OK; Gross reject |
| Icterus | Mild OK; Gross reject |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum Red | Refrigerated (preferred) | 14 days |
| Ambient | 14 days | |
| Frozen | 14 days |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Theophylline and its congener, aminophylline, are used to relax smooth muscles of the bronchial airways and pulmonary blood vessels to relieve and prevent symptoms of asthma and bronchospasm.
Theophylline is administered orally at a dose of 400 mg/day or 6 mg/kg, whichever is lower, or intravenously as aminophylline at 0.6 mg/kg/hour. Oral dosage may be increased at 200-mg increments to a maximum of 900 mg/day, or 13 mg/kg if the steady-state blood concentration is within the therapeutic range of 10.0 to 20.0 mcg/mL.
Theophylline has a half-life of 4 hours in children and adult smokers, and 7 hours in nonsmoking adults, thus steady-state is reached in approximately 1 day. The volume of distribution is 0.5 L/kg, and the drug is approximately 50% protein bound. Theophylline exhibits zero-order clearance kinetics like phenytoin, small increases in dose yield disproportionately large increases in blood concentration.
Coadministration of cimetidine and erythromycin will significantly inhibit theophylline clearance, requiring dosage reduction. Other drugs such as allopurinol, ciprofloxacin, oral contraceptives, and propranolol inhibit theophylline clearance to a lesser degree.
Smoking induces the synthesis of cytochrome P448, the antipyrine-dependent cytochrome, which significantly increases the rate of metabolism of theophylline. Drugs such as phenobarbital, phenytoin, carbamazepine, and rifampin slightly increase the rate at which the drug is cleared.
Theophylline exhibits rather severe toxicity that is proportional to blood level.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
Therapeutic
Children and adults: 8.0-20.0 mcg/mL
Neonatal apnea: 6.0-11.0 mcg/mL
Toxic concentration: > or =20.0 mcg/mL
Interpretation Provides information to assist in interpretation of the test results
Response to theophylline is directly proportional to serum level.
Patients usually receive the best response when the level is >10.0 mcg/mL, with minimal toxicity experienced as long as the level is <20.0 mcg/mL.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Many drugs affect the plasma level of this drug (as outlined in Clinical Information).
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Pesce AJ, Rashkin M, Kotagal U: Standards of laboratory practice: theophylline and caffeine monitoring. Clin Chem 1998, May;44(5);1124-1128
2. McCudden CR, Broussard LA: Caffeine, lithium and theophylline. In Therapeutic Drug Monitoring Data: A Concise Guide, 3rd edition, Edited by CA Hammett-Stabler, A Dasgupta, AACC Press, 2007
3. Vassallo R, Lipsky JJ: Theophylline: recent advances in the understanding of its mode of action and uses in clinical practice. Mayo Clin Proc 1998;73:346-354
Method Description Describes how the test is performed and provides a method-specific reference
This method is performed by enzyme-multiplied immunoassay technique (EMIT) using an Olympus analyzer. The EMIT assay is a homogeneous enzyme immunoassay technique used for the analysis of specific compounds in biological fluids. The assay is based on competition for antibody binding sites between drug in the specimen and drug labeled with the enzyme glucose-6-phosphate dehydrogenase (G6P-DH). Enzyme activity decreases upon binding to the antibody, so the drug concentration in the specimen can be measured in terms of enzyme activity. Active enzyme converts oxidized nicotinamide adenine dinucleotide (NAD) to NADH, resulting in an absorbance change that is measured spectrophotometrically. Endogenous serum G6P-DH does not interfere because the coenzyme functions only with the bacterial enzyme employed in the assay.(Package insert: EMIT Amikacin Assay, Syva Company, Siemens Healthcare Diagnostics, Newark, DE, February 2007)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Sunday; Varies
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
80198
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 8661 | Theophylline, S | 4049-3 |
External
link
PDF
document
Excel
document
Word
document