What Chronic Kidney Disease Is Doing to the Philippines — and Why Farmers and Laborers Are at Highest Risk

How Large the CKD Burden Already Is

Globally, 788 million adults aged 20 and older are estimated to have chronic kidney disease as of 2023, more than double the 378 million affected in 1990, according to the GBD 2023 study published in The Lancet in November 2025. The global age-standardized prevalence among adults now stands at 14.2 percent. CKD is the ninth leading cause of death globally, claiming nearly 1.5 million lives in 2023, and the 12th leading cause of disability worldwide. In the Philippines, CKD is a leading public health burden: diabetic nephropathy, the kidney damage caused by uncontrolled diabetes, is the most common cause of end-stage renal disease requiring dialysis. The Philippine Renal Disease Registry has consistently documented rising rates of new dialysis patients, straining a healthcare system where the cost of long-term dialysis is substantial and access outside Metro Manila and major regional centers is uneven. PhilHealth covers hemodialysis sessions through its outpatient dialysis package, but coverage gaps and geographic inequity in dialysis facility availability remain documented challenges.

The traditional narrative centers on the diabetes and hypertension pipeline: poor glycemic and blood pressure control over years, leading to nephron damage, declining glomerular filtration rate, and eventually end-stage renal disease. That pathway is real and well-documented. But it is not the only pathway. And for a country where a significant proportion of the working population, including farmers, construction workers, fisherfolk, and informal sector laborers, works under sustained heat exposure without adequate water, rest, and shade, a second pathway deserves urgent attention.

The Non-Traditional Form of CKD That Climate Change Is Amplifying

Chronic kidney disease of non-traditional etiology, abbreviated CKDnt and sometimes called CKD of unknown etiology or CKDu, was first recognized as a distinct epidemic in the 1990s along the Pacific coast of Central America, where young male sugarcane workers were dying of kidney failure in large numbers despite being otherwise healthy and having no history of diabetes, hypertension, or other traditional CKD risk factors. Subsequent research identified the condition in Sri Lanka's North Central Province, where prevalence among paddy farmers ranged from 6 to 15 percent, and in Taiwan, where CKDnt was found in 1.5 percent of farmers compared to 0.4 percent of nonfarmers.

A 2025 systematic review and meta-analysis published in PLOS Neglected Tropical Diseases found that geographic latitude and temperature are statistically significant moderators of CKD risk in these non-traditional epidemic regions: each one degree Celsius increase in ambient temperature in CKDnt epidemic regions was associated with an 8 percent increase in CKD risk. This finding positions CKDnt as a climate-sensitive disease in a way that makes tropical countries like the Philippines directly relevant to the emerging evidence base, even where local epidemiological data on CKDnt specifically remains limited.

The biological mechanism centers on recurrent episodes of heat-induced acute kidney injury that do not fully resolve between exposures. Under sustained heat and physical exertion, blood is redirected away from the kidneys to supply muscles and skin, reducing renal blood flow. Combined with fluid losses through sweating that are not adequately replaced, this causes transient but real reductions in kidney function. Repeated over days, weeks, and harvest seasons, this pattern causes cumulative scarring and fibrosis in kidney tissue. A theoretical framework developed from both sports physiology and occupational health literature identifies release of pro-inflammatory substances from heat-stressed gut tissue and muscle, combined with the accumulation of fructose and uric acid in kidney tubules under dehydration, as key contributors to kidney inflammation that eventually becomes permanent.

Why Filipino Outdoor Workers Face Compounded Risk

The Philippines has among the largest outdoor and informal agricultural labor forces in Southeast Asia. Rice farming alone employs millions of workers, many of whom perform heavy manual labor during transplanting and harvest seasons in lowland areas where heat index values regularly reach dangerous levels. The connection between this workforce and CKDnt risk mirrors the conditions documented in Central America and Sri Lanka: low-lying tropical environments, strenuous physical work, heat exposure during peak daytime hours, limited access to potable water in the field, and economic pressure that discourages rest breaks.

A systematic review published in the International Journal of Biometeorology in June 2025 concluded that outdoor workers, particularly male workers, face an elevated risk of CKD linked to climate change, and identified cooling techniques, work-rest cycles, shade provision, and adequate hydration as the most evidence-supported preventive strategies. In Nicaragua, a water-rest-shade intervention implemented mid-harvest was sufficient to prevent kidney function decline among cane workers with low to moderate workloads but not among those with the heaviest workloads, suggesting that even protective interventions have limits when heat stress is extreme enough. The research underscores that for the most physically demanding work under the highest heat conditions, structural changes to work schedules, not just behavioral recommendations, are needed.

• Construction workers, brick makers, fisherfolk, and mining workers have all been documented as CKDnt-affected occupational groups in non-agricultural settings internationally
• CKDnt primarily affects young men aged 20 to 50, a demographic that would not typically be prioritized for CKD screening under traditional risk-factor criteria
• Early kidney injury from heat stress is detectable through simple urine and blood tests, including elevated creatinine, reduced estimated glomerular filtration rate, and urinary biomarkers of tubular damage
• There is no cure for CKD once it reaches moderate to severe stages; prevention through occupational heat management and hydration is the only effective intervention

What the Response Needs to Look Like

At the clinical level, expanded kidney function screening for outdoor workers in high-heat occupations would allow early detection before CKD progresses to symptomatic or end-stage disease. A simple creatinine and urinalysis at annual occupational health checks would suffice as a first-line screen. At the occupational policy level, the DOLE's existing Occupational Safety and Health Standards could be strengthened with specific provisions on heat exposure limits, mandatory water and rest schedules for outdoor workers during peak heat months, and shade requirements at agricultural and construction worksites. These are not novel interventions. They are adaptations of measures already shown to slow kidney function decline in comparable settings internationally.

PhilHealth's dialysis coverage, while meaningful, is a downstream response to a problem that should be addressed upstream. The cost of end-stage renal disease, in terms of dialysis sessions, hospitalization, and productivity loss, vastly exceeds the cost of occupational heat management programs. From a health economics standpoint, preventing CKDnt in outdoor workers is among the most cost-effective public health investments the Philippines can make as the climate continues to warm and heat index values in the danger range become an increasingly routine feature of the working year.