Traditional Indian medicines can cause membranous nephropathy

Membranous nephropathy (MN) is a progressive kidney disease which is characterized by the accumulation of immune complexes within the kidney. It often leads to a so-called nephrotic syndrome with proteinuria, hypoalbuminemia, and edema, it can even result in kidney failure. MN can occur without any known causes (primary MN), but can also be acquired via other diseases. Antibodies against phospholipase A2 receptor (PLA2R) are highly specific for the primary form of the disease, but do not occur in secondary forms.
An Indian working group published five cases of nephrotic syndrome caused by MN with evidence of chronic mercury poisoning due to consumption of traditional Indian medicines such as Siddha and Ayurveda. The article was published in “Clinical Kidney Journal” (ckj), an official journal of the ERA-EDTA, in June 2018, and is the first report of its kind showing that traditional Indian medicines can cause MN, proven by renal biopsy. All patients received this kind of medicine and the index patients were seronegative for antibodies against phospholipase A2 receptor (PLA2R), giving evidence that they did not suffer from the primary form of the disease.
Very few cases of mercury-induced MN have been reported in the literature so far and most known cases have developed due to traditional Chinese medicine, skin-lightening creams, inhalation containing mercury and hair dye containing mercury. Traditional Indian medicines have so far not been “on the radar”, although mercury has been an ingredient in several traditional medicines such as Ayurveda, Unani, Siddha, Tibetan and Chinese medicines. Traditional Indian medicines are sold over the Internet and have found a global market. However, these drugs sold by some traditional medicine manufacturers may not be rigorously tested for the contents and their sale is not regulated. However, despite the widespread consumption of traditional Indian medicines, no renal toxicity has been reported so far. According to the authors of this case report, it might be possible that it is underreported due to a lack of awareness among physicians and nephrologists or to a lack of knowledge: very often, patients do not even mention that they are taking traditional medicines in addition to what their family doctor or nephrologist prescribes.
The authors suggest that mercury poisoning should be considered in patients with anti-PLA2R antibody-negative MN, and that these patients should be asked, if they had taken traditional Indian medicines.
“The publication of these case reports is important. It shows that seemingly harmless traditional medicine can harm people a lot and that it is high time that controls and regulations concerning the ingredients of any medicine are needed”, explains ckj editor-in-chief, Professor Alberto Ortiz. “As long as there are no quality controls for substances used in traditional medicine, we have to warn our patients: Mercury poisoning can lead to MN as well as to many other severe health problems, because it is affecting the brain, the gut and the kidneys.”