Urolithiasis

Urolithiasis (from Greek oûron, "urine" and lithos, "stone") is the condition where urinary calculi are formed or located anywhere in the urinary system, or the process of forming stones in the kidney, bladder, and/or ureters (urinary tract).

Kidney stones are a common cause of blood in the urine and pain in the abdomen, flank, or groin. Kidney stones occur in one in 20 people at some time in their lives. The stones form in the urine-collecting area (the pelvis) of the kidney and may range in size from tiny to staghorn stones the size of the renal pelvis itself.

Etiology and pathology
The development of the stones is related to:
 * Decreased urine volume
 * Increased excretion of stone-forming components
 * Inadequate urine drainage, which may lead to stasis
 * Decrease in urinary citrate levels leading to Ca2+ deposition
 * Deficiency of vitamins A or C - these conditions can also lead to the "hyper triad" - hyperparathyroidism, hypercalcaemia, and hyperuricosuria.

The term nephrolithiasis (or "renal calculus") refers to stones located in the kidney, while ureterolithiasis refers to stones in the ureter. The term cystolithiasis (or vesical calculi) refers to stones which form or have passed into the bladder.

Composition of stones
The most common stone is calcium oxalate (dihydrate) - spicules, while the hardest stone is cystine monohydrate. Other stone compositions include triple phosphate, ammonium, magnesium, urate calcium, oxalate, urate, xanthine, etc.

Clinical features

 * In the kidney, fixed renal pain (flank pain) is common.
 * In the ureter (according to localisation of stone): If in the upper one-third of the ureter - pain radiates to the perineum, if at the pelvic brim - pain radiates to the inner aspect of the thigh, if present in the middle one-third of ureter - pain radiates to the iliac fossa.
 * If the stone is localised in the bladder neck or urethra - pain may present as tip of penis pain. Frequency of urination, oliguria, dribbling of urine, and hematuria may increase.