Kidney Stones: How They Form and Why They Keep Coming Back

Anyone who has experienced kidney stones remembers it vividly. The pain is intense, and the cramping sensation radiates from the back or side down toward the groin. Kidney stones are painful, but the most frustrating thing about them is that this pain frequently comes back.

Recurrence may occur in half of all kidney stone patients within five years, and in as many as 80% within ten years. However, it is important to understand the reasons stones form in the body and what causes their recurrence. It is essential to know this for anyone who is at risk of developing one.

How kidney stones form

• The kidneys are responsible for filtering waste products from the blood and excreting them through the urine. These waste products dissolve in the urine and pass out of the body without any problems under normal circumstances. However, kidney stone formation begins when some minerals and salt in the urine become too high. This state is called supersaturation.
• Crystal begins to form at this point and binds together to create a solid mass called a kidney stone.
• The most common type of such stone is calcium oxalate, which is present in approximately 80% of cases. Some less common types are uric acid stones, struvite stones and crystine stones. They form due to underlying metabolic or dietary factors.

The following conditions may lead to supersaturation in the urine:

• Low urine volume: When a person does not drink enough fluids, the urine becomes concentrated. So it gives less room for minerals to stay dissolved.
• High levels of calcium, oxalate, or uric acid in the urine are present due to diet, metabolic conditions, or genetic predisposition.
• Low levels of citrate in the urine: Citrate limits crystal formation, so reduced citrate levels leave the kidney more vulnerable.
• Urinary tract infections from certain bacteria can change urine chemistry and cause struvite stones.

Why the local context matters?

Urinary stones are present in approximately 12% of the population. The hot and dry climate may contribute to this problem. Sweating increases in such conditions, which leads to dehydration. Therefore, the urine has more minerals that may lead to kidney stone formation.

The diet is also important to avoid kidney stones. There is a stone belt across states in the northern and central part of the country, because of the food habits. They may include high protein and dairy consumption, which are the main reasons for kidney stones.

A diet rich in oxalate-containing foods such as spinach, tomatoes, and nuts, along with insufficient fluid intake, creates a perfect condition for stone formation.

Symptoms and when to seek care

Small kidney stones pass through the urinary tract on their own without causing symptoms. However, larger stones can become lodged and lead to the following symptoms:

• Severe, wave-like pain in the back, side, or lower abdomen
• Pain or burning during urination
• Blood in the urine, which may appear pink, red, or brown
• Nausea and vomiting accompany the pain
• Frequent urge to urinate or difficulty doing so
• Fever and chills, if an infection is also present

Fever alongside kidney stone symptoms requires urgent medical attention, as it may indicate an infected kidney. This situation can become serious quickly.

Why kidney stones recur?

Once a person has formed stone, the underlying conditions, whether dietary, metabolic, or anatomical, remain in place, unless they are addressed. There is a chance of developing another stone within 25 years of the first episode in approximately 98% of patients. This high recurrence rate of nephrolithiasis is the most significant feature.

Common reasons for kidney stone recurrence are mentioned below:

• Returning to the same dietary habits that contributed to the first stone
• Inadequate fluid intake in warm weather or during physical activity
• Hyperparathyroidism, gout, or chronic urinary tract infections
• The kidneys are more prone to crystal formation due to genetic predisposition

How kidney stones are managed and prevented?

Treatment of an active kidney stone depends on its size and location. Pain relief can help with small stones and pass naturally with high fluid intake. Larger stones require a medical procedure to remove them. It may include ureteroscopy, shock wave lithotripsy, or percutaneous nephrolithotomy.

Prevention is the most necessary step to manage this problem in the long run. Adequate fluid intake is the most important measure for nephrolithiasis prevention. A urine output of at least 2 to 2.5 litres per day may reduce the concentration of minerals. It will lower the risk of crystal formation. Low salt diet should be advised to all recurrent stone formers. Also patients should take normal dietary intake of calcium and avoid Calcium and vitamin C supplements. Lifestyle changes , exercise and weight reduction are important . Also changes in diet specific to type of stone are recommended. In general, recurrent stone formers should increase their intake of fruits and vegetables. 

Also recurrent stone formers require few blood tests and 24 hour urine test to find out the cause for stone and ascertain the type of stone. Stone analysis can be done if a patient passes the stone spontaneously or if the stones are surgically removed.  Based on the reports, patients can  be started on medications to prevent further stone formation .

Takeaways

A higher concentration of minerals in the urine leads to kidney stones. These minerals crystallise over time and bind together to form a mass. The most common type of kidney stone is calcium oxalate, which forms due to diet, lack of hydration and metabolic reasons.

If underlying conditions are not addressed, kidney stone recurrence rates remain high. So, most patients may see the stone form within a few years. The best way to prevent kidney stones is to increase fluid intake and make some dietary changes. Patients with recurrent nephrolithiasis should get their metabolic factors checked to identify and treat the specific cause.