PRIME TRIGGER

Heat stress dominates debate on the causes of a mysterious chronic kidney disease that continues to baffle health experts and is on the rise globally

- SEEMA PRASAD

MORE THAN 30 years and 35 countries. These are the only definitive data available about the chronic kidney disease of unknown origin or CKDU-a condition whose mysterious nature is evident from its name.

Chronic kidney disease, which is characterised by progressive loss of kidney function, is usually reported among those suffering from diabetes, hypertension and glomerulonephritis (a type of kidney inflammation), or those who have inherited genetic diseases that damage this key filter system of the body. But scientists have so far not been able to pinpoint what causes CKDU. This knowledge gap hampers efforts to prevent new cases and slow progression of the disease, which can be fatal. Doctors say the condition usually remains undiagnosed until kidney failure.. What's alarming is that the prevalence of CKDU is on the rise globally.

CKDU was first identified in Sri Lanka and India in the 1990s. Soon, the disease was also reported from Central American countries. According to a review paper published in Environmental Geochemistry and Health on September 12, 2022, CKDU was initially limited to tropical countries. But in the last three decades, it has been reported from 35 countries, including the US and UK. Though no data is available on the global burden of CKDU, the paper estimates that the disease could be responsible for over 30,000 deaths a year and that Sri Lanka and India have the highest number of people affected by CKDU.

According to the Indian Chronic Kidney Disease Burden 2022, published in Clinical Kidney Journal, 19.5 per cent of all chronic kidney disease patients in the country are classified as CKDU. The rate is on par with chronic kidney disease triggered by diabetes (24.9 per cent) and by cervical intraepithelial neoplasia (23.2 per cent), characterised by abnormal growth of cells on cervix.