Heat stress is a condition that results when the body temperature exceeds the individual’s ability to dissipate that heat which is typically above 104 degrees Fahrenheit of body temperature and when humidity is greater than 70%. It includes heat cramps, heat exhaustion, heat rash or heat stroke. Heat exhaustion is characterized by heavy sweating and rapid pulse. Without prompt treatment, it can lead to heat stroke which is a severe life-threatening condition. When humidity is high, sweating becomes less effective at dissipating heat and the core body temperature begins to rise. Heat illness usually affects multiple organs including kidneys. Infants and young children, teenage athletes and elderly population with pre-existing illnesses like her disease are at high risk for heat stroke.
Heat stroke results from exposure to extreme heat resulting in hyperthermia with the temperature of more than 104 deg F, that can lead to delirium, coma, seizures and multi-organ failure. Heat stroke can occur during extreme heat waves and also in association with extreme exercise or labor, which is termed as Exertional heat stroke. Heat stress affects kidneys in multiple ways. Predominantly it causes severe dehydration, low blood pressure and reduced perfusion to the kidneys resulting in acute kidney injury. Heat stress can cause breakdown of muscle tissue (rhabdomyolysis) which releases a protein called myoglobin, that can cause damage to the tubules inside the kidneys. During severe episodes of heat stroke, heart failure and shock can cause acute kidney injury.
There can be heat-induced direct inflammatory injury to the kidneys. Heat stress related kidney injury is worsened by higher core temperatures, dehydration, longer work duration, muscle damaging exercise, and consumption of beverages.
Many of the manual workers who work under extremely hot conditions in various hot regions in the world can manifest with chronic kidney disease which is termed as ‘heat stress nephropathy’. It happens due to repeated episodes of acute kidney injury due to subclinical or clinical heat stroke. Heat stress also predisposes to the formation of kidney stones. Dehydration due to heat stress results in urinary concentration and low urine volumes that increase the risk for stones. Urinary tract infections may also be related to underhydration.
How to counter heat stress
· Immediately shift the patient suspected to have heat stress to a cooler environment.
· External cooling by means of mists plus fan, cool shower or put in cool tub of water,
· Ice packs to the head and neck, remove clothing and applying cool compresses
· Ice bath can also be used
· Adequate hydration is also very important.
Dr. Vinod Kumar, Consultant – Nephrology & Renal Transplantation, Aster RV Hospital