Herbs and supplements in dialysis patients: panacea or poison?

The safety of herbal remedies and supplement use is of particular concern in patients with renal disease, and reliable information is not always easy to find. Predialysis patients may be drawn to complementary and alternative medicine (CAM) because they believe it can help prevent the progression of their renal disease. The purpose of this series of articles on alternative medicine for nephrologists is to address concerns and issues specific to CAM use in dialysis patients and to provide a guide to reliable sources of information. This introductory article emphasizes safety issues with a focus primarily on herbal medicine. Lack of regulation means that patients may not actually be taking what they think they are. Independent laboratory analyses have shown a lack of stated label ingredients and many instances of supplements and traditional remedies being contaminated with pesticides, poisonous plants, heavy metals, or conventional drugs. While certain supplements are always unsafe (carcinogenic, hepatotoxic, glandular extracts), others are specifically contraindicated in renal disease. Supplement use may be especially hazardous in renal disease because of unpredictable pharmacokinetics, drug interactions, negative effects on kidney function, nephrotoxicity, hemodynamic alterations, unpredictable effects on blood pressure or blood glucose, or potentiation of electrolyte abnormalities. There are no data on potential dialyzability of either active compounds, or their potentially active or toxic metabolites. Many supplements contain metal ions and other minerals. Transplant recipients are also at risk from potential unpredictable effects on immune function. Recommendations and information resources are listed.