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Theophylline and Caffeine Blood Test

Last updated Sept. 16, 2016

The Theophylline and Caffeine Blood Tests are tests that measure the levels of theophylline and caffeine in circulation. They are used when adjusting the initial doses. They are also used to ensure that their levels stay within an acceptable range.


What are other names for this test? (Equivalent Terms)

  • Methylxanthines Blood Test
  • Xanthines Blood Test

What is Theophylline and Caffeine Blood Test? (Background Information)

  • Theophylline and caffeine are structurally similar chemicals that have a stimulant effect on the body. They are found naturally in chocolate, coffee, and tea. They can also be artificially administered for therapeutic use
  • Theophylline and caffeine belong to a group of chemicals, called xanthines. Xanthines resemble one of the 5 bases present in DNA and RNA, which is adenine, denoted by the alphabet A. The other 4 are cytosine, C; thymine, T; uracil, U; and guanine, G
  • Aside from its role in DNA and RNA, adenine also serves as a signaling molecule in many bodily processes; it does this in its nucleoside form, adenosine. One of the processes in which adenosine plays a signaling role is during relaxation and fatigue
  • Adenosine binds to adenosine receptors of the central nervous system (CNS). When it binds, it depresses activity and relaxes the CNS. The levels of bound adenosine escalate with the progression of the day and fluctuates with the circadian rhythm
  • Since, theophylline and caffeine resemble adenosine structurally, they bind to some of the same receptors, to which adenosine binds. However, when theophylline or caffeine bind, they do not exert the same depressant effects that adenosine exerts, when it binds
  • This property of theophylline and caffeine to competitively antagonize adenosine receptors in the CNS, gives rise to their stimulant effects. In effect, these molecules increase one’s energy and alertness, by preventing adenosine from binding and exerting its depressant effects
  • Theophylline and caffeine increase the heart rate and body metabolism. They also dilate the bronchioles in the lungs, expanding the airways. These effects make theophylline and caffeine useful in counteracting asthma attacks and apnea
  • The Theophylline and Caffeine Blood Tests are tests that measure the levels of theophylline and caffeine in circulation. They are used when adjusting the initial doses. They are also used to ensure that their levels stay within an acceptable range

What are the clinical indications for performing the Theophylline and Caffeine Blood Test?

Following are the clinical indicators for performing a Theophylline and Caffeine Blood Test:

  • Monitoring theophylline and caffeine therapy
  • Low blood pressure
  • Abdominal pain
  • Jitteriness
  • Unresponsiveness to theophylline and caffeine therapies

How is the specimen collected for Theophylline and Caffeine Blood Test?

Following is the specimen collection process for Theophylline and Caffeine Blood Test:

Sample required: Blood

Process: Insertion of a needle into an arm vein.

Preparation required: No special preparation is needed prior to the test.

What is the significance of the Theophylline and Caffeine Blood Test result?

The significance of Theophylline and Caffeine Blood Test is explained:

  • Excessive theophylline and caffeine levels may indicate toxicity, which is marked by:
    • Nausea
    • Restlessness
    • Altered mental status and confusion
  • Low theophylline and caffeine levels may indicate that higher amounts are needed to achieve a therapeutic dose

The laboratory test results are NOT to be interpreted as results of a "stand-alone" test. The test results have to be interpreted after correlating with suitable clinical findings and additional supplemental tests/information. Your healthcare providers will explain the meaning of your tests results, based on the overall clinical scenario.

Additional and relevant useful information:

  • Theophylline and caffeine are excreted through urine. Conditions that diminish the kidneys’ function, diminish the body’s capacity to excrete these two chemicals

Certain medications that you may be currently taking may influence the outcome of the test. Hence, it is important to inform your healthcare provider, the complete list of medications (including any herbal supplements) you are currently taking. This will help the healthcare provider interpret your test results more accurately and avoid unnecessary chances of a misdiagnosis.

What are some useful resources for additional information?

DoveMed is currently working to bring you additional resources.

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References and information sources used for the article:

Lab Tests Online (2012, June 8). Retrieved June 7, 2014 from http://labtestsonline.org/understanding/analytes/theophylline/

Martini, F., Nath, J. L., & Bartholomew, E. F. (2012). Fundamentals of anatomy & physiology (9th ed.). San Francisco: Benjamin Cummings.

Nehlig, A. (1992). Caffeine and the central nervous system: mechanisms of action, biochemical, metabolic and psychostimulant effects. Brain Research Reviews17(2), 139-70.

Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: June 8, 2014
Last updated: Sept. 16, 2016