Ariyawansha, R.T.K.Basnayake, B.F.A.Dharmasena, D.A.N.Siribaddana, S.2026-05-112025-09-092961-5011https://rda.sliit.lk/handle/123456789/4975There are many research studies conducted to determine the cause/origin of CKDu for preventing this increasingly occurring disease, particularly among poor farmers. The disease is known to be multifactorial with heat stress enduring period > 3 months, but there is difficulty in distinguishing between harsher environments than endemic locations. This study identified that the likely cause is UVB actuating Vitamin D Toxicity (VDT), thus affecting the kidneys. Hence, a focused literature review was undertaken to find the links between cadmium (Cd), calcium, fluoride, enzymes, inhibitions, and the like. Moreover, 2nd law of thermodynamics was applied to determine the entropy differences between cold and hot source. The mean values of climate models were obtained from one publication on radiative forcing (RF) in the tropopause of 1.28 Wm- 2 and climate feedback (CF) 0.25 Wm-2K-1. The energy of RF was used to determine entropy value 𝑆𝑅𝐹(𝑈𝑉𝐵)at 𝑇2 = 230𝐾 as mean atmospheric temperature and the maximum temperature, 𝑇1 at locations. It was then equated to the energy value of UVB, 𝑄𝐶𝐹(𝑈𝑉𝐵) to be found between 1/273 and 1/𝑇1. It was also validated using CF. The endemic location resulted 3.697 Wm-2 at 303K, and low RH compared to 3.239 Wm-2 at 311 K high RH. Although there is much comfort in endemic location, the chances of VDT or heat stress are higher more so with Cd inhibition of enzyme 7-dehydrocholesterol reductase (DHCR7), which is crucial for cholesterol synthesis. Instead, 7-dehydrocholesterol in excess switches more to form VDT, causing symptomatic hypercalcemia. Cadmium can disrupt vitamin D metabolism, contributing to osteomalacia and osteoporosis, actuating hypercalciuria, an indirect marker of low-level cadmium exposure. The kidneys, already compromised due to cadmium (Cd) accumulation and reabsorption during systemic distribution, ultimately eliminate Cd via the urine. Notably, no significant Cd accumulation is observed in end-stage renal tissues. Further basic research is required to elucidate the VDT in response to UVB exposure.enCadmiumCkduClimate FeedbackHypercalcemiaVitamin D Toxicity (Vdt)Radiative Forcing7- Dehydrocholesterol Reductase (Dhcr7) INTRODUCTIONConference Paperhttps://doi.org/10.54389/CAHZ3412