Excessive intake of which of these causes necrosis of PCT -a) Mercuryb) Alcoholc) Arsenicd) Phenol
**Core Concept**
The question assesses the nephrotoxic effects of various substances on the proximal convoluted tubule (PCT) of the kidney. The PCT is responsible for reabsorbing glucose, amino acids, and other essential nutrients from the filtrate back into the bloodstream.
**Why the Correct Answer is Right**
Excessive intake of certain substances can cause necrosis of the PCT by disrupting normal cellular functions. Arsenic is a well-known nephrotoxin that can cause damage to the PCT by inhibiting the enzyme glutathione S-transferase, leading to oxidative stress and cellular injury. This results in the loss of renal function and potentially acute kidney injury (AKI). In contrast, mercury and phenol are also nephrotoxins, but they primarily affect the distal convoluted tubule and collecting ducts, respectively. Alcohol can cause a range of renal effects, but it is not as directly toxic to the PCT as arsenic.
**Why Each Wrong Option is Incorrect**
**Option A:** Mercury is more toxic to the distal convoluted tubules and collecting ducts, causing damage to the renal cortex and potentially leading to Fanconi syndrome.
**Option B:** Alcohol can cause a range of renal effects, including acute kidney injury, but it is not as directly toxic to the PCT as arsenic.
**Option D:** Phenol is a local anesthetic and analgesic that can cause renal damage, but it is more toxic to the collecting ducts and renal cortex.
**Clinical Pearl / High-Yield Fact**
Remember the mnemonic "ARSENIC" to recall the nephrotoxic effects of arsenic: Acute Renal failure, Severe Nephrotoxicity, End-stage Kidney disease, and Increased Creatinine levels.
**Correct Answer:** C. Arsenic