What Are the Main Types of Kidney Stones?
Calcium Stones
Calcium-based stones account for the largest proportion of kidney stone cases. Despite their name, they are not caused by excess dietary calcium alone and typically occur in two forms: calcium oxalate and calcium phosphate.
- Calcium OxalateThis is the most frequently encountered subtype. Calcium oxalate stones form when oxalate, found in foods such as nuts, chocolate and certain fruits and vegetables, combines with calcium in the urine. Factors such as low fluid intake, high oxalate consumption and conditions that increase urinary calcium can all raise the likelihood of stone formation.
- Calcium PhosphateCalcium phosphate stones are less common and are often linked to metabolic conditions that affect the body’s acid–alkali balance. Renal tubular acidosis is a notable example, as it alters urine chemistry in a way that encourages crystal development.
Uric Acid Stones
Uric acid stones develop when urine becomes persistently acidic, allowing uric acid to crystallise. Unlike calcium stones, they can form even when calcium levels in the urine are normal.
These stones are more likely in people who consume purine-rich foods such as red meat, organ meats and shellfish, as well as those with gout, diabetes or obesity. Because uric acid stones do not show up on standard X-rays, imaging such as CT scans is often required for accurate detection.
Struvite Stones
Struvite stones, sometimes referred to as infection stones, arise from chronic or recurrent urinary tract infections caused by bacteria that produce the enzyme urease. This enzyme raises urine alkalinity, creating an environment that promotes the formation of magnesium ammonium phosphate crystals.
What makes struvite stones particularly concerning is their ability to grow rapidly. In some cases, they can develop into large “staghorn” stones that occupy much of the kidney. Symptoms may be subtle at first, but untreated stones can lead to serious complications and require prompt intervention.
Cystine Stones
Cystine stones are rare and occur in individuals with cystinuria, a hereditary metabolic disorder. In this condition, the kidneys excrete excessive amounts of the amino acid cystine into the urine.
Because cystine dissolves poorly, it can crystallise and form stones, often beginning in childhood or adolescence. People with cystinuria may experience repeated stone episodes throughout their lives, making ongoing management particularly important.
Does the Type of Stone Influence Treatment?
The composition of a kidney stone plays a crucial role in determining both immediate management and long-term prevention.
Medical Dissolution Therapy
Uric acid stones are unique in that they can often be dissolved without surgery. Treatment focuses on alkalinising the urine, usually with medications such as potassium citrate, to prevent further crystal formation.
Surgical Intervention
Most other stone types, including calcium, struvite and cystine stones, may need to be removed if they cause symptoms or obstruction. Common approaches include extracorporeal shockwave lithotripsy (ESWL), ureteroscopy and percutaneous nephrolithotomy (PCNL).
Preventive Dietary and Medication Adjustments
Preventing recurrence depends on understanding the stone type.
- Calcium Stones: Management may involve reducing sodium and animal protein intake, increasing hydration and, in some cases, using thiazide diuretics.
- Struvite Stones: Prevention centres on treating the underlying urinary infection and ensuring complete stone removal to minimise recurrence.
When to Seek Medical Attention
The sudden, severe pain associated with a kidney stone is often debilitating and is a sign that the stone is moving or causing a blockage. You should seek immediate medical attention if you experience:
- Excruciating pain in your back, side or lower abdomen that comes in waves
- Blood in your urine (haematuria)
- Fever and chills, which could indicate a severe infection (pyelonephritis) behind the stone obstruction, requiring urgent treatment
- Nausea and vomiting
Taking the Right Step Towards Diagnosis and Treatment
Whether kidney stones are a new concern or a recurring issue for you, seeing a specialist early can make a real difference. Prompt assessment helps avoid complications, clarifies what is happening and allows treatment to be tailored to your specific stone type, supporting long-term prevention and protecting your kidney health.
To arrange a consultation and receive personalised advice, contact our clinic today and take the next step towards effective treatment and lasting peace of mind.
