American Association for Clinical Chemistry
Better health through laboratory medicine
March 2011 Clinical Laboratory News: AACC’s Expert Access
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March 2011: Volume 37, Number 3



AACC's Expert Access
Unexpected Laboratory Test Results: The Effects of Herbal Remedies 

Each month, AACC’s Expert Access Live Online Program features a different hot topic. Visit AACC’s website for more information and an archive of past presentations.

The following is an excerpt from the March 2011 presentation by Amitava Dasgupta, PhD, DABCC, professor of Pathology and Laboratory Medicine at the University of Texas Medical School at Houston, and director of the Clinical Chemistry and Toxicology Laboratory of Memorial-Hermann Laboratory Services.

Please explain the differences between homeopathic medicine and herbal supplementation.
Herbal supplements have active ingredients in microgram to milligram quantities in one dose of remedy. By contrast, one dose of a homeopathic medicine may contain only a single molecule, or even no molecules, of active ingredient, because homeopathic remedies are made from a very high dilution of the active ingredient. For example, each St. John’s wort capsule contains approximately 100 micrograms of hypericin. In contrast, homeopathic medicine prepared from St. John’s wort may not even contain a single molecule of hypericin.

Are you aware of instances in which remedies labeled as “herbal” or “natural” actually contain over-the-counter (OTC) medicines? Also, is there any place where you can find out if a remedy contains substances not on the label?
Many herbals imported from China and other Asian countries are known to be contaminated with both OTC medicines, such as acetaminophen, salicylate, and/or other prescription drugs, including harmful steroids. Currently, there is no database to find such an answer rapidly. Herbals manufactured in U.S. and Europe, however, are free from such contaminants.

There is a lot of marketing for detoxification or herbal cleansing products. What is your opinion of these, and do any particular herbs in these preparations cause interference with lab tests?
Herbal detoxification or herbal cleansing products have no known scientific efficacy. Some products may contain caffeine and may falsely elevate urinary caffeine levels. Golden seal tea is used in some herbal cleansing products that can interfere with immunoassays used for drugs-of-abuse testing, especially EMIT assays.

Are there any herbs that affect thyroid testing performed by immunoassay?
To my knowledge, herbs do not interfere with thyroid test by immunoassay. However, kelp (seaweed) contains high amounts of iodine, and if taken as a supplement, may cause abnormality in thyroid function reflected in thyroid testing.

Do salt substitutes affect serum potassium levels? Are there any herbal or other dietary supplements that affect serum potassium levels?
Salt substitutes containing potassium may elevate potassium level to a small extent, but not outside the normal range. For herbals, licorice may cause abnormal potassium levels if taken for a long period.

Is there any way to know that herbal medicines could be the cause of an incorrect lab result?
Not really, because we do not test for herbals in the clinical lab. However, if we see abnormal test results and suspect they are due to use of a herbal, we call the clinician and recommend that he/she question the patient regarding use of herbal preparations. Patients are usually forthcoming about their use of such products.

Disclaimer—The opinions and information are the sole responsibility of the presenter. AACC reviews the presentation for overall appropriateness, but this should not be construed as an endorsement by the association or its employees of the opinions and information offered here.