Alcohol is a commonly consumed substance around the world, however chronic excessive alcohol consumption can have detrimental effects on the kidneys. Understanding the impacts of alcohol on kidney health is important.
How does alcohol affect the kidneys?
Alcohol is metabolized by the liver, where it produces toxic byproducts that can damage cells and organs over time. Two of the main byproducts are acetaldehyde and reactive oxygen species. Acetaldehyde can damage kidney tubules and impair kidney function. Reactive oxygen species can lead to oxidative damage and inflammation in kidney tissue.
Alcohol also inhibits the production and release of an antidiuretic hormone called vasopressin from the pituitary gland. Vasopressin regulates fluid balance in the body. With less vasopressin, the kidneys are less able to conserve water which leads to increased urination and dehydration.
Dehydration from excessive alcohol puts additional strain on the kidneys. Over time, the combination of direct toxicity, oxidation, inflammation, and dehydration can impair kidney function.
Long term effects of alcohol on the kidneys
Some of the main long term effects of excessive alcohol consumption on the kidneys include:
- Alcoholic kidney disease – Damage to the tubules and glomeruli impairs kidney function leading to decreased glomerular filtration rate. Can range from mild to severe dysfunction.
- Electrolyte imbalances – Alcohol impacts kidney tubules leading to impaired reabsorption of electrolytes like sodium, potassium, chloride, magnesium and phosphate.
- Kidney stones – Dehydration and electrolyte imbalance increases risk of kidney stones.
- High blood pressure – Alcohol can raise blood pressure via impacts on kidney function and fluid regulation.
- Urinary system infections – Increased risk of infections such as cystitis, pyelonephritis and urethritis.
- Kidney cancer – Studies show links between chronic heavy alcohol use and increased risk of renal cell carcinoma.
- End stage renal disease – Severely impaired kidney function that requires dialysis or kidney transplant.
People who drink heavily for extended periods have a higher risk of developing some degree of alcoholic kidney disease. The amount of alcohol intake that can start to cause kidney damage varies by individual.
Stages of alcoholic kidney disease
Alcoholic kidney disease typically progresses through a series of stages:
- Kidney enlargement – Early stage with enlarged kidneys due to inflammation but normal kidney function.
- Proteinuria – Spilling of protein into the urine due to glomerular damage.
- Loss of kidney function – Glomerular filtration rate decreases as damage accumulates.
- End stage renal disease – Severe loss of kidney function that requires dialysis or transplant.
The rate of progression through these stages depends on the amount and duration of alcohol intake as well as the presence of other factors like smoking, obesity, genetics, diet, infections, etc.
Kidney enlargement
In the earliest stages of alcoholic kidney disease, the kidneys often become enlarged. This is due to:
- Inflammation from acetaldehyde toxicity
- Increased renal blood flow in early stages of kidney disease
- Swelling of tubule cells and glomeruli
Kidney enlargement may be detectable on physical exam or imaging studies like ultrasound or CT scan. At this stage kidney function is still normal as measured by glomerular filtration rate and creatinine levels.
Proteinuria
As kidney damage progresses, the glomeruli become unable to properly filter blood and proteins start spilling out into the urine. This proteinuria occurs once the glomerular filtration barrier is compromised by scarring and inflammation. Indicators include:
- Increased urine protein-to-creatinine ratio
- Presence of high molecular weight proteins in urine
- Positive urine dipstick for protein
Proteinuria may signal the transition from kidney enlargement to the loss of kidney function in alcoholic kidney disease.
Loss of kidney function
With continued alcohol intake, damage to the nephrons leads to impaired kidney function. Signs include:
- Decreased glomerular filtration rate (GFR)
- Increased serum creatinine
- Imbalanced electrolytes
- Inability to concentrate urine
- Anemia
- High blood pressure
This marks the progression to chronic kidney disease. The extent of function loss depends on severity and duration of alcohol consumption. Even after alcohol cessation, kidney function may continue declining.
End stage renal disease (ESRD)
ESRD occurs when kidney function has deteriorated to less than 15%. At this stage, kidney failure symptoms are severe enough to require dialysis or a kidney transplant. ESRD is irreversible and life-threatening without renal replacement therapy. Approximately 2.5% of ESRD cases in the U.S. are attributed to alcohol abuse.
Factors that influence kidney damage
Not all drinkers develop severe kidney disease. Factors that influence an individual’s risk include:
- Amount of alcohol intake – Binge drinking and high total alcohol consumption increase risk more than moderate intake.
- Duration of alcohol abuse – Long term alcoholism is worse than short term.
- Gender – Some research shows women may be more vulnerable to alcohol’s kidney effects.
- Genetics – Family history of kidney disease increases susceptibility.
- Other health conditions – Diabetes, hypertension, liver disease can all exacerbate kidney damage.
- Diet – Poor nutrition adds stress to kidneys.
- Tobacco use – Smoking worsens kidney injury from alcohol.
- Race – Black people tend to be more prone to kidney disease.
Reversing alcoholic kidney damage
The progression of alcoholic kidney disease can be halted or potentially reversed if alcohol misuse is stopped in time. However, there seems to be a point of no return when the kidneys are too scarred for recovery of function. This window of reversibility depends on individual drinking patterns and kidney health status.
With mild kidney impairment, cessation of alcohol accompanied by proper hydration, diet, and medications may allow kidneys to heal and regain normal filtration capacity. More severe proteinuria and loss of function may still stabilize but not fully improve. Once end stage disease is reached, damage is difficult to reverse.
In addition to giving up alcohol, steps to help reverse kidney damage include:
- Drinking plenty of fluids
- Eating a low-salt, low-protein kidney diet
- Achieving ideal weight
- Controlling blood sugar and blood pressure
- Medications like ACE inhibitors or ARBs
- Quitting smoking
- Avoiding nephrotoxic drugs
Those with advanced kidney disease may still progress to end stage despite alcohol abstinence. But giving up alcohol can help slow damage and prolong remaining kidney function.
Diagnosing alcoholic kidney damage
Some tests that can help diagnose alcohol’s effects on the kidneys include:
- Blood tests – Creatinine, BUN, GFR, electrolytes
- Urine tests – Proteinuria, albuminuria, urine protein/creatinine ratio
- Imaging – Ultrasound, CT showing enlarged kidneys
- Kidney biopsy – Examining glomeruli and tubules microscopically
- History – Significant alcohol use
The presence of enlarged kidneys, proteinuria, and abnormal kidney function in the setting of a history of alcohol abuse can provide evidence for alcoholic kidney disease. However, doctors still typically screen for other potential causes as well.
Preventing alcoholic kidney damage
The most effective way to prevent alcoholic kidney damage is to avoid excessive alcohol intake. Moderation is key. Consuming no more than 1-2 standard drinks per day for men and 1 drink per day for women can help limit risk. Additional tips include:
- Drink water between alcoholic beverages
- Eat while drinking to slow absorption
- Avoid binge drinking episodes
- Monitor for signs of kidney disease with routine blood and urine testing
- Get help for alcohol abuse and addiction issues
- Manage other medical conditions like diabetes and high blood pressure
For those already living with alcoholic kidney disease, complete alcohol cessation is advised to prevent further progression to end stage disease. Ongoing kidney function monitoring and damage control are important.
Conclusion
Excessive long term alcohol intake has numerous detrimental effects on the kidneys. It can lead to inflammation, scarring, proteinuria, electrolyte abnormalities, and loss of kidney function. While mild cases may improve with alcohol abstinence, severe damage often continues to progress. Preventing alcoholic kidney disease with moderation and managing coexisting conditions are key. Anyone with a history of heavy drinking should have periodic kidney screening exams for early detection.