Kidney Stones Specialist — Valencia

Understanding kidney stones

Kidney stones are hard mineral deposits that form inside the kidneys when substances in the urine — calcium, oxalate, uric acid and others — become too concentrated and crystallise. They are extremely common, affecting roughly one in ten people during their lifetime, and the risk rises in hot, dry climates like the Mediterranean coast. For expats, retirees and tourists adapting to Valencia’s summers, dehydration is a frequent and avoidable trigger.

Types of kidney stones

Not all stones are the same, and knowing the type guides both treatment and prevention:

• Calcium oxalate stones are by far the most common, accounting for the majority of cases. They form when urine contains too much calcium or oxalate, often combined with low fluid intake.
• Uric acid stones form in acidic, concentrated urine and are linked to high animal-protein diets, gout, obesity and dehydration. They are more frequent in hot climates.
• Struvite stones are associated with certain urinary tract infections. They can grow quickly into large “staghorn” stones and usually require surgical removal.
• Cystine stones are rare and caused by an inherited disorder (cystinuria) in which the kidneys leak too much of the amino acid cystine into the urine.

Symptoms: the experience of renal colic

When a stone moves into the ureter — the narrow tube draining the kidney — it can cause renal colic, one of the most intense pains in medicine. The pain typically starts in the flank or back and comes in waves as the ureter contracts, often radiating down towards the groin. Many patients also notice blood in the urine (haematuria), nausea, vomiting and a frequent urge to pass urine. A stone causing blockage combined with fever and chills is a medical emergency, as it can lead to a serious kidney infection.

How kidney stones are diagnosed

The diagnostic workup usually includes:

• Non-contrast CT scan — the gold standard, showing the size, number and exact location of stones, and the most sensitive test for confirming the diagnosis.
• Ultrasound — useful as a first test, especially for younger patients and in pregnancy, where avoiding radiation matters; it also detects blockage of the kidney.
• Urinalysis — looking for blood, crystals, infection and urine acidity.
• Blood tests and stone analysis — measuring calcium, uric acid and kidney function, and analysing any passed stone to identify its composition.

For recurrent stone-formers, a 24-hour urine collection measures the key stone-forming and protective substances, allowing a tailored prevention plan.

Acute management versus prevention

Acute management focuses on relieving pain and dealing with the stone. Small stones often pass naturally with hydration, anti-inflammatory pain relief and sometimes medication to relax the ureter. Larger or obstructing stones may need shock-wave lithotripsy (breaking the stone with focused energy) or keyhole procedures performed by a urologist.

Preventive management is where lasting benefit lies, because half of stone-formers will form another stone within five to ten years without prevention. Based on stone type and 24-hour urine results, a nephrologist may recommend dietary changes, increased fluids and, in some cases, medications such as thiazides for calcium stones or alkalinising treatment for uric acid stones.

Diet, hydration and the Mediterranean heat

For most patients, prevention starts with fluids. Aim to produce around 2 to 2.5 litres of urine daily — more in Valencia’s summer, when sweating concentrates the urine. Keeping your urine pale is a reliable everyday guide.

Dietary adjustments depend on the stone type but commonly include reducing salt, moderating animal protein, maintaining a normal (not restricted) calcium intake from food, and limiting high-oxalate foods only when relevant. A balanced Mediterranean diet with plenty of fruit and vegetables tends to be protective, partly because of its citrate and potassium content.

Nephrologist or urologist?

A simple way to think about it: the urologist treats the stone you have now, while the nephrologist works to stop the next one forming. If you suffer recurrent stones, have abnormal kidney function or a metabolic cause, ongoing nephrology care — clearly explained in English for international patients in Valencia — helps protect your kidneys for the long term.

References

1. EAU Guidelines on Urolithiasis 2023. European Association of Urology. uroweb.org
2. Türk C, et al. EAU Guidelines on Diagnosis and Conservative Management of Urolithiasis. Eur Urol. 2016;69(3):468–474. PubMed 26318710
3. Curhan GC, et al. A prospective study of dietary calcium and other nutrients and the risk of symptomatic kidney stones. N Engl J Med. 1993;328(12):833–838. PubMed 8451427
4. Ferraro PM, et al. Dietary protein and potassium, diet-dependent net acid load, and risk of incident kidney stones. Clin J Am Soc Nephrol. 2016;11(10):1834–1844. PubMed 27445166