Renal Calculi (Kidney Stones)

Renal calculi, or kidney stones, are hard deposits that form inside the kidneys from crystallised minerals and salts in urine. They can cause severe pain when they move within the urinary tract or block the flow of urine.

• Sudden, severe pain in the back or side, often radiating toward the lower abdomen or groin ("loin to groin" pain), that comes in waves
• Blood in the urine
• Nausea and vomiting
• Pain or burning on urination if the stone is closer to the bladder
• Fever and chills if infection is also present, which is a more urgent situation

• Formed when substances in urine, such as calcium, oxalate, or uric acid, become concentrated and crystallise, often related to inadequate fluid intake.
• Risk is increased by dehydration, certain diets, some medical conditions affecting mineral metabolism, and a family history of kidney stones.

• Suspected based on the characteristic sudden, severe, colicky flank pain.
• Urinalysis often shows blood in the urine.
• Ultrasound is commonly used to detect stones and assess for any resulting blockage or kidney swelling (hydronephrosis); CT scan, where available, is more sensitive for smaller stones.
• Blood tests assess kidney function, particularly if there is a suspected blockage.

Pain relief, typically with an NSAID such as diclofenac, together with adequate hydration, is the initial treatment for most kidney stones, as many small stones pass on their own.

An alpha-blocker medicine may be used to help relax the ureter and support passage of the stone.

Stones associated with fever, signs of infection, or complete blockage of urine flow are a medical emergency requiring urgent hospital-level care, as an infected, obstructed kidney can rapidly become life-threatening.

Larger stones, or those that do not pass on their own, may require specialist procedures to break up or remove the stone.

Straining urine to catch a passed stone, where feasible, can help identify its composition and guide future prevention.

• Drink plenty of water throughout the day to keep urine dilute.
• Reduce salt intake, as high salt intake increases calcium in the urine.
• Follow any specific dietary advice given based on the type of stone identified.
• Seek prompt medical care for severe flank pain, and immediate care if it is accompanied by fever or an inability to pass urine.