Alcohol and Kidney Stones

Many analogies can help explain the function of our kidneys: two bean-shaped organs located in the back of the abdomen with an internal structure resembling an apple tree, a purification chamber, and a colander. 

The kidneys act as colanders. Blood flows through the blood vessels and into the kidneys’ capillary network. Toxins in the body, either consumed (e.g. drugs, food additives, pesticides), or produced through chemical reactions necessary for bodily function, are excreted through the urinary system.

What enters the renal system as ‘bad’ leaves the system as ‘clean blood’ via an exchange of water, salts, and toxins. This filtered blood is then re-circulated back to the body.¹ The kidneys also maintain fluid and electrolyte balance by keeping the right amount of salt and water in our blood in response to our hydration status and blood pressure.

Filtered waste products can sometimes form crystals that collate inside the kidney, called kidney stones. 

What are Kidney Stones?

Kidney stones (also known as ‘renal calculus’ or ‘nephrolithiasis’) affect more than 1 in 10 people, generally between the ages of 30 to 60.² They are pebble-like structures that can be present in one or both kidneys, varying in size from a grain of sand to the size of a pea - some cases have even been reported as being the size of a golf ball. This condition can be self-limiting (i.e. the condition will resolve on its own), as smaller kidney stones can pass through the urinary tract without any or with minimal discomfort.

However, some larger stones may become lodged in the urine tract. This would block urine flow and lead to several issues, such as pain and bleeding, severe lower back and abdomen pain, nausea, fever, and urine infection.³

There are many causes for kidney stones: for example, lack of fluid, certain medications, and having a medical condition that raises levels of certain minerals in your urine. There has been some discussion of the effect of alcohol on the occurrence of kidney stones, which shall be explored further below. Aside from this, several risk factors predispose you to kidney stones, including diet, genetics, cardiovascular-related factors, lifestyle, and behavioural risk factors.

Types of Kidney Stones

There are four main types of kidney stones:^1,2

Calcium oxalate

This is the most common type of stone and occurs when calcium combines with oxalate. This often occurs, but is not limited to, when there is insufficient calcium and fluid intake.

Uric acid

These stones (also very common) can be caused by the increased production of monosodium urate. Higher production of monosodium urate can be caused by high purine intake. Purines are a natural chemical compound found in various food and drink, for example, shellfish, organic meat, and alcohol. The formation of this type of kidney stone is often linked with genetics. 

Struvite

These are caused by infections in the upper urinary tract from bacteria. Bacteria release ammonia as a waste product, which makes urine more alkaline. This causes the formation of struvite stones. These stones can grow large very quickly, often with very few symptoms initially. 

Cystine

These stones are caused by a rare genetic disorder known as cystinuria. This is when a natural component found in the body known as ‘cystine’ leaks into the urine. High levels of cystine in the urine cause the formation of cystine stones. This is a lifelong condition that can not be cured (i.e. those with cystinuria often have recurring stones) but symptoms can be managed. 

Treatment

Treatment can consist of increasing fluid intake to 3 litres a day and taking medication for symptom management (e.g. painkillers, anti-sickness medication, and medication to help the stone pass, known as alpha-blockers). Depending on the type of stone, dietary adjustments may be necessary (e.g. cutting down on a high-protein diet). For larger kidney stones, surgical interventions may be used, with the type of surgery depending on the size and location of the stones.⁴

To prevent kidney stones, increase your daily water intake, add fresh lemon to water, and avoid drinks high in sugar and foods high in salt. The general rule is that urine should be ‘clear’ rather than dark in colour. 

Can Alcohol cause Kidney Stones?

There is currently no evidence that suggests there is a direct link between the consumption of alcohol and the emergence of kidney stones. However, the interconnectivity of our organ systems means that overconsumption of alcohol may have a direct effect on a system or condition that consequently increases the likelihood of the production of kidney stones. 

The main indirect cause would be the ‘diuretic’ properties of alcohol, meaning it causes water to be drawn out of the body. The effect of dehydration on the kidney can be serious. The minerals in urine cannot be removed from the body without sufficient fluids, so being dehydrated means that the kidney will find it more difficult to remove waste from the body, increasing the likelihood of kidney stones forming.^5,6,7

On the other hand, some studies have explored how alcohol could potentially help prevent or treat kidney stones. A study that explored the effect of different beverages on the risk of kidney stones reported that sweetened soda and punch are associated with a higher risk of stone formation, while coffee, tea, beer, wine, and orange juice are associated with a lower risk. This risk reduction is suggested to be due to the diuretic effect of alcohol on smaller, passable stones.

In other words, drinking a beer will trigger your urge to pass urine - if you do so, the kidney stones can be removed before they get any bigger. It is important to note that water will similarly encourage you to pass urine and is the healthiest option. In contrast, dehydration due to the diuretic properties of alcohol can lead to water retention, causing the opposite effect via urinating less, making the kidney stones more difficult to pass.^5,6,7

While alcohol is a large part of society, it does not come without risk. It is recommended that people should drink under 14 units a week, equivalent to 14 single shots of spirit, 6 pints of beer, or 10 small glasses of wine. This drinking should be spread over 3 days or more and should be in between drink-free days to ensure health risks from alcohol are minimal. There are many unit converter apps to monitor one’s drinking.⁸

Alcohol causes our kidneys to work a lot harder: frequent urination due to the diuretic properties of alcohol and waste products in the kidney not being excreted can lead to several kidney-related complications. Below is a brief synopsis of common causes of kidney pain after drinking. If you suffer from any of these, see your doctor or pharmacist for advice.⁹

1. Liver disease: often a likely cause for those suffering from alcoholism. Liver disease impairs blood flow to the kidney, which affects filtering potential.

2. Kidney stones: as discussed, alcohol-induced dehydration can cause kidney stones to move out of the urinary tract much slower than usual, increasing pain and discomfort, especially if the stones are of a larger variety.

3. Kidney infection: a urinary tract infection where alcohol consumption may worsen symptoms. 

4. Dehydration: alcohol makes you urinate more than usual, leading to dehydration. It does not allow the kidney to maintain water or electrolyte balance, potentially leading to kidney stones.

5. Ureteropelvic junction (UPJ) obstruction: a blockage in the kidney, often caused by the connection between the ureter and renal pelvis narrowing, causing urine to build up and damage the kidney. Alcohol can intensify this pain. 

6. Hydronephrosis: swollen kidney due to an accumulation of urine - the blockage stops the urine from travelling from the kidneys to the bladder, leading to further swelling in the renal pelvis. Kidney stones can lead to hydronephrosis.

7. Gastritis: inflammation of the stomach lining can be caused by excess alcohol consumption - while not directly part of the renal system, the pain experienced with gastritis may be experienced in the upper abdomen and linked to kidney pain. 

8. Appendicitis: inflammation of the appendix, causing pain in a similar area to the kidney.

Kidney stones have been coined ‘great mimickers’ as they present with similar signs and symptoms to the aforementioned conditions. This highlights the importance of speaking to a medical professional if you are concerned about anything you have read. While alcohol, like other fluids, has been reported to lower the risk of kidney stone development by allowing smaller kidney stones to pass via the urinary system, this is a double-edged sword. Alcohol can lead to dehydration due to frequent urination, weight gain, and it also contributes to issues relating to high purine levels, all of which increase the likelihood of kidney stones.¹⁰ 

If you are suffering from an addiction to alcohol or drugs, or know someone who is, support systems are available at a local, national, and global front. Here are some below:¹¹

• Drinkline is the national alcohol helpline. If you are worried about your own or someone else's drinking, you can call this free helpline in complete confidence. Call 0300 123 1110 (weekdays 9am to 8pm, weekends 11am to 4pm).
• Alcoholics Anonymous (AA) is a free self-help group. Its 12-step programme involves getting sober with the help of regular support groups. 
• Adfam is a national charity working with families affected by drugs and alcohol. Adfam operates an online message board and a database of local support groups.