Review of Abnormal Laboratory Test Results and Toxic Effects Due to Use of Herbal Medicines

Amitava Dasgupta, PhD

Am J Clin Pathol. 2003;120(1)

Abstract and Introduction

Abstract

Herbal medicines are used widely in the United States, and according to a recent survey, the majority of people who use herbal medicines do not inform their physicians about their use. Herbal medicines can cause abnormal test results and confusion in proper diagnosis. Herbal medicines can alter test results by direct interference with certain immunoassays. Drug-herb interactions can result in unexpected concentrations of therapeutic drugs. For example, low concentrations of several drugs (eg, cyclosporine, theophylline, digoxin) can be observed in patients who initiated self-medication with St John's wort. Herbal medicines can alter physiology, and these changes can be reflected in abnormal test results. For example, kava-kava can cause drug-induced hepatitis, leading to unexpected high concentrations of liver enzymes. Use of toxic herbal products such as ma huang (an ephedra-containing herbal product), Chan Su, and comfrey may cause death. Other toxic effects of herbal medicines include cardiovascular toxic effects, hematologic toxic effects, neurotoxic effects, nephrotoxic effects, carcinogenic effects, and allergic reactions.

Introduction

Herbal medicines, including Chinese herbal products, are readily available in the United States from health food stores without prescriptions. Ayurvedic medicines are used widely in India, and some preparations are available in the United States. Ginseng, St John's wort, ma huang, kava, ginkgo biloba, Dan Shen, feverfew, garlic, ginger, saw palmetto, comfrey, pokeweed, hawthorn, dong quai, and cat's claw are used by the general population in the United States. Intended uses of common herbal medicines are given in Table 1 . Gulla et al^[1] published a survey of 369 patient-escort pairs and reported that 174 patients (47.2%) used herbs. The most common herbal product used was ginseng (20%) followed by echinacea (19%), ginkgo biloba (15%), and St John's wort (14%).^[1]

Several herbal products interfere with immunoassays used for monitoring the concentrations of therapeutic drugs. Herbal medicines also can cause toxic effects, leading to abnormal test results. Therefore, the common belief that anything natural is safe is not correct. This review summarizes abnormal test results associated with the use of herbal medicines, as well as interactions between Western medicines and herbal products. This review also summarizes the toxic effects of commonly used herbal products.

1 2 3 4 5 6 7

Next Section

Cite this: Review of Abnormal Laboratory Test Results and Toxic Effects Due to Use of Herbal Medicines - Medscape - Jul 01, 2003.

Table 1. Intended Uses of Common Herbal Medicines
Herbal Medicine	Intended Use
Ginseng	Tonic capable of invigorating users physically, mentally, and sexually; also used for dealing with stress; used in China for more than 5,000 y
Siberian ginseng	Similar to ginseng
St John's wort	Treatment of mood disorders, particularly depression
Ginkgo biloba	Mainly to sharpen mental focus in otherwise healthy adults and also in people with dementia; improvement of blood flow in the brain and peripheral circulation; treatment of diabetes mellitus-related circulatory disorders, impotence, and vertigo
Kava	Relief of anxiety and stress; sedative
Valerian	Treatment of insomnia
Echinacea	Immune stimulant that helps increase resistance to colds, influenza, and other infections; wound healing
Saw palmetto	Treatment of benign prostatic hypertrophy
Feverfew	Relief from migraine headache and arthritis
Garlic	To lower cholesterol levels and blood pressure; prevention of heart attack and stroke
Ginger	Prevention of motion sickness, morning sickness, and nausea
Cranberry	Treatment of urinary tract infection; decrease kidney stone formation
Aloe	To heal wounds, burns, skin ulcers; also used as a laxative
Senna	Laxative
Dong quai	To alleviate problems associated with menstruation and menopause
Cat's claw	Immunostimulant with antiviral activity; also used by people with AIDS; prevention of colds and influenza; treatment of chronic fatigue syndrome
Hawthorn	For heart failure, hypertension, and angina pectoris
Pokeweed	Antiviral and antineoplastic; eating uncooked berry or root may cause serious poisoning

Table 2. Interference of Herbal Products in Therapeutic Drug Monitoring of Digoxin*
Herbal Product	Level of Interference	Comments
Chan Su	High	Chan Su has active components such as bufalin, which cross-react with digoxin assays; only Bayer assay has no interference; monitoring free digoxin also eliminates interference
Dan Shen	Moderate	Falsely elevated (FPIA) or falsely low (MEIA) digoxin level; no interference with EMIT, Bayer, Randox, Roche, or Beckman assays; monitoring free digoxin eliminates interference
Uzara root (diuretic)		Additive effect with digoxin; also interferes with digoxin assay
Siberian ginseng	Moderate	Falsely elevated (FPIA) or falsely low (MEIA) digoxin level; no interference with EMIT, Bayer, Randox, Roche, or Beckman assays; monitoring free digoxin does not eliminate interference
Asian ginseng	Moderate	Falsely elevated (FPIA) or falsely low (MEIA) digoxin level; no interference with EMIT, Bayer, Randox, Roche, or Beckman assays; monitoring free digoxin does not eliminate interference
FPIA, fluorescence polarization immunoassay; MEIA, microparticle enzyme immunoassay.
* Bayer Diagnostics, Tarrytown, NY; Roche Diagnostics, Indianapolis, IN; Beckman Coulter, Fullerton, CA.

FPIA, fluorescence polarization immunoassay; MEIA, microparticle enzyme immunoassay.

* Bayer Diagnostics, Tarrytown, NY; Roche Diagnostics, Indianapolis, IN; Beckman Coulter, Fullerton, CA.

Table 3. Common Drug-Herb Interactions
Herbal Product	Interacting Drug	Comments
Ginseng	Warfarin	Ginseng may decrease effectiveness of warfarin
Ginseng	Phenelzine	Toxic symptoms, eg, headache, insomnia, and irritability
St John's wort	Paroxetine hydrochloride	Lethargy, incoherence, nausea
	Digoxin	Decreased AUC; peak and trough concentration of digoxin; may reduce effectiveness of digoxin
	Cyclosporine	Lower cyclosporine concentration due to increased clearance may cause transplant rejection
	Theophylline	Lower concentration, thus decreases the efficacy of theophylline
	Indinavir	Lower concentration may cause treatment failure in patients with HIV
Ginkgo biloba	Aspirin	Bleeding; ginkgo can inhibit PAF
	Warfarin	Hemorrhage
	Thiazide	Hypertension
Kava	Alprazolam	Additive effects with CNS depressants, alcohol
Garlic	Warfarin	Increased effectiveness of warfarin; bleeding
Ginger	Warfarin	Increased effectiveness of warfarin; bleeding
Feverfew	Warfarin	Increased effectiveness of warfarin; bleeding
Dong quai	Warfarin	Dong quai contains coumarin; dong quai increases INR for warfarin, causes bleeding
Dan Shen	Warfarin	Increased effectiveness of warfarin owing to reduced elimination of warfarin
Soy milk	Warfarin	Causes decline in INR
Comfrey	Phenobarbital	Increased metabolism of comfrey producing a lethal metabolite from pyrrolizidine; severe hepatotoxic effects
Borage oil	Phenobarbital	May lower seizure threshold, requiring dosage increase
Evening primrose oil	Phenobarbital	May lower seizure threshold, requiring dosage increase
Licorice	Spironolactone	May offset the effect of spironolactone
Shankhapushpi	Phenytoin	Lower phenytoin level and loss of seizure control

AUC, area under the curve; CNS, central nervous system; INR, international normalized ratio; PAF,
platelet-activating factor.

Table 4. Potentially Toxic Herbs
Herb	Toxic Effect or System Affected	Intended Use (Should Anyone Use?)
Comfrey	Hepatotoxic	Repairing of bone and muscle; prevention of kidney stones
Ephedra	Cardiovascular	Herbal weight loss
Chan Su	Cardiovascular	Tonic for heart
Borage oil	Hepatotoxic; hepatocarcinogenic	Source of essential fatty acids; rheumatoid arthritis; hypertension
Calamus	Carcinogenic	Psychoactive, not promoted in the United States
Chaparral	Hepatotoxic; nephrotoxic; carcinogenic	General cleansing tonic; blood thinner; arthritis remedy; weight loss product
Licorice	Pseudoaldosteronism (sodium and water	Treatment of peptic ulcer; flavoring agent retention, hypertension, heart failure)

Comments

Commenting is limited to medical professionals. To comment please Log-in.

Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.