Cigarette smoking is a leading cause of preventable diseases and deaths globally. While the detrimental effects of smoking on the lungs and heart are widely recognised, its impact on kidney health is often overlooked.
According to Dr. Saurabh Pokhariyal, Chief Medical Director, VitusCare, the kidneys, crucial organs responsible for filtering waste and toxins from the blood, regulating fluid balance, and maintaining blood pressure, are particularly susceptible to the harmful effects of smoking. Smoking can impair kidney function, accelerate the progression of chronic kidney disease (CKD), and increase the risk of kidney cancer.
How Smoking Affects Kidney Health?
Cigarette smoke comprises over 7,000 chemicals, including nicotine, tar, carbon monoxide, and heavy metals such as cadmium. These substances not only harm the lungs and cardiovascular system but also have a direct and profound impact on the kidneys.
Here’s how smoking contributes to kidney damage:
Reduced Blood Flow to the Kidneys: Healthy kidney function relies on an adequate supply of oxygen-rich blood. Smoking damages blood vessels and causes them to narrow (vasoconstriction), reducing blood flow to vital organs, including the kidneys. This impaired blood circulation, known as renal hypoperfusion, limits the kidneys’ ability to filter toxins and waste products effectively, leading to functional decline over time.
Oxidative Stress and Cellular Damage: Cigarette smoke is a major source of oxidative stress, a condition in which the body is overwhelmed by unstable molecules called free radicals. These molecules damage cells and tissues, including those in the kidneys. The toxins in cigarette smoke also trigger inflammation, further harming the kidneys and contributing to scarring, or fibrosis, which permanently reduces their filtering capacity.
Increased Blood Pressure/ Hypertension and Kidney Damage: Hypertension, or high blood pressure, is a leading cause of kidney damage. Smoking exacerbates hypertension by constricting blood vessels, increasing heart rate, and inducing the release of stress hormones such as adrenaline. Elevated blood pressure forces the kidneys to exert greater effort, accelerating wear and tear on the filtering units known as glomeruli. Over time, this leads to chronic kidney disease.
Worsening Diabetes: Related Kidney Damage: Diabetes is another significant risk factor for kidney disease, and smoking further worsens the condition in several ways. It reduces insulin sensitivity, making it more challenging to control blood sugar levels. Uncontrolled diabetes damages the minute blood vessels in the kidneys, a condition known as diabetic nephropathy. Smokers with diabetes are at a substantially higher risk of kidney failure compared to non-smokers with diabetes.
Increased Protein Leakage in the Urine: One of the early indicators of kidney damage is proteinuria, the presence of excess protein in the urine. Smoking enhances the permeability of the kidney’s filtration barrier, leading to an increased leakage of protein into the urine. Persistent proteinuria serves as a marker of kidney damage and a predictor of a faster progression to advanced stages of kidney disease.
Higher Risk of Kidney Cancer: Smoking is a well-established risk factor for renal cell carcinoma, the most prevalent form of kidney cancer. Carcinogenic chemicals present in cigarette smoke, such as cadmium and nitrosamines, damage the DNA in kidney cells, resulting in mutations and tumor formation. Research indicates that smokers are at least twice as likely to develop kidney cancer compared to non-smokers, and the risk escalates with the number of cigarettes smoked and the duration of smoking.
Chronic Kidney Disease and Smoking: Chronic kidney disease (CKD) is a progressive condition characterized by the gradual decline of the kidneys’ ability to function. It affects millions of individuals globally, and smoking significantly contributes to its development and progression.
“Smokers are at a higher risk of developing chronic kidney disease (CKD) compared to non-smokers, and once diagnosed, their condition tends to progress more rapidly. This is because smoking exacerbates the primary drivers of kidney damage, including hypertension, oxidative stress, and proteinuria. Smokers with CKD are also more likely to progress to end-stage renal disease (ESRD), a condition in which the kidneys can no longer function without dialysis or a kidney transplant.” Dr. Pokhariyal told Financial Express.com.
Cardiovascular Complications: Chronic kidney disease (CKD) and cardiovascular disease are closely interconnected, and smoking exacerbates both conditions. The reduced blood flow induced by smoking not only damages the kidneys but also increases the risk of heart attacks, strokes, and other vascular complications. Smokers with CKD face a significantly higher risk of cardiovascular mortality compared to non-smokers with the same condition.