Sparked by climate change, a new era of climate medicine has indeed dawned, wherein new diseases triggered by heat extremes and environmental degradation could be on the rise, CKDu being one such.

The socio-economic burden of chronic kidney disease (CKD) has been growing in Kerala as in the rest of the country.

But over the past five years or more, a significant increase in young patients with CKD of undetermined cause — a fairly new entity, ‘CKD of unknown aetiology (CKDu)’ — has been confounding nephrologists.

CKDu, first reported in 1990s in Central America, where an unusually large number of agricultural workers exposed to very hot and humid weather conditions and dehydration were succumbing to renal failure, is emerging as a global problem with similar disease patterns being reported from select geographical regions in tropical nations, including Sri Lanka and India.

The disease is still poorly understood but there is international consensus that there is an inexorable link between CKDu, heat exposure, dehydration, and other environmental stressors. Sparked by climate change, a new era of climate medicine has indeed dawned, wherein new diseases triggered by heat extremes and environmental degradation could be on the rise, CKDu being one such.

The crowded Nephrology OP at Government Medical College, Thiruvananthapuram, has also been a witness to this steady rise in the number of men, in their most productive ages, presenting with late stages of CKD, when only thrice-weekly dialysis or a renal transplant can help them live.

“From some 30-40 patients a day way back in 2006, today I see around 300 or 400 patients in my OP. What is worrying is the steady increase in this group of patients, who constitute 20-30% of the OP cases. Men in their 30s or 40s, often manual labourers in Gulf countries, in stage 3 or 4 of CKD, with shrunken kidneys and none of the usual clinical manifestations of CKD and without a history of classic causes such as diabetes, hypertension, or glomerular disease,” says Noble Gracious, Associate Professor of Nephrology.

NEJM editorial

In India, similar disease patterns have been reported from Uddanam in Andhra Pradesh, parts of Odisha, and Tamil Nadu. The fact that CKDu could be a form of heat-stress nephropathy, possibly because of the rapidly changing global temperature and environment conditions, is the focus of the August 22 issue of New England Journal of Medicine (NEJM).

“Our knowledge gap hampers efforts to prevent new cases, slow disease progression, and treat late-stage disease. What we do know for certain is that CKDu is related to heat exposure and dehydration, although exposure to agrochemicals, heavy metals, and infectious agents, as well as genetic factors and risk factors related to poverty, malnutrition, and other social determinants of health may also contribute,” says the editorial.

In fact, there is increasing evidence on how extreme exposure to heat and poor hydration can cause daily subclinical acute kidney injury. Also consider the fact that all geographical regions where CKDu has been reported have undergone substantial climatic and environmental changes in recent times.

The first population-based evidence of CKDu in India, using standardised methods, comes from the study ‘Prevalence of and risk factors for chronic kidney disease of unknown aetiology in India: secondary data analysis of three population-based cross-sectional studies.’ (BMJ Open March 2019).

“CKDu has to be a multi-factorial entity and cannot be attributed to rise in temperatures alone. One should also make a distinction between the 5-10% unexplained CKD cases in an urban OP, which is often a type of chronic tubular interstitial disease and CKDu, as we see in the rural agrarian communities, which is more linked to the environment,” says Sreejith Parameswaran, Head of Nephrology at JIPMER, Pondicherry.