Listed in Issue 138


DASGUPTA and BERNARD, Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Houston, TX 77030, USA,, have reviewed (98 references) the effects of herbal remedies on clinical laboratory tests.


Herbal medicines can affect laboratory test results by several mechanisms. The aim of this study was to summarize and comment published reports on effects of herbal remedies on abnormal laboratory test results.


All published reports between 1980 and 2005 with the key words herbal remedies or alternative medicine and clinical laboratory test, clinical chemistry test, or drug-herb interaction were searched through Medline. The authors’ own publications were also included. Important results were then synthesized.


Falsely elevated or falsely lowered digoxin levels may be encountered in a patient taking digoxin and the Chinese medicine Chan Su or Dan Shen, owing to direct interference of a component of Chinese medicine with the antibody used in an immunoassay. St John’s wort, a popular herbal antidepressant, increases clearance of many drugs, and abnormally low cyclosporine, digoxin, theophylline, or protease inhibitor concentrations may be observed in a patient taking any of these drugs in combination with St John’s wort. Abnormal laboratory results may also be encountered owing to altered pathophysiology. Kava-kava, chaparral, and germander cause liver toxicity, and elevated alanine aminotransferase, aspartate aminotransferase, and bilirubin concentrations may be observed in a healthy individual taking such herbal products. A herbal product may be contaminated with a Western drug, and an unexpected drug level (such as phenytoin in a patient who never took phenytoin but took a Chinese herb) may confuse the laboratory staff and the clinician.


Use of herbal medicines may significantly alter laboratory results, and communication among pathologists, clinical laboratory scientists, and physicians providing care to the patient is important in interpreting these results.


Dasgupta A, Bernard DW. Herbal remedies: effects on clinical laboratory tests. Archives of Pathology & Laboratory Medicine 130 (4): 521-528, Apr 2006.

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