Urolithiasis – colloquially called urinary stone disease – (synonyms: calculi renali; urinary bladder stones; urinary calculus; urinary stone diathesis; caliceal stones; nephroliths; nephrolithiasis; renal pelvic stones; renal calculi; ICD-10 N20-N23: urolithiasis) is the formation of urinary stones in the kidney and/or the urinary tract. They can be found in the kidney, ureters (urinary tract), urinary bladder, or urethra (urethra). Urinary stones are caused by an imbalance in the physicochemical composition of urine with formation of salt crystals. Stone size varies from micrometers to several centimeters. Urolithiasis is divided according to the location of the stone into:
| Localization | Frequency |
| Nephrolithiasis (kidney stones) | 97 % |
| Ureterolithiasis: ureteral stones (ureteral calculi). | |
| Cystolithiasis (urinary bladder stones). | 3 % |
| Urethralithiasis (urethral calculi); special form:calculus renalis (pl. calculi renali), this is a kidney stone (renal calculus) that has migrated into the urethra |
In clinical usage, only the terms “nephrolithiasis” and “urolithiasis” are usually used. One can divide urolithiasis based on the cause of origin:
| Cause of origin | Stone type | Frequency |
| Acquired metabolic disorder | Calcium oxalate stone | 75 % |
| Uric acid stone | 11 % | |
| Uric acid dihydrate stone | 11 % | |
| Brushite Stone | 1 % | |
| Carbonate apatite stone | 4 % | |
| Urinary tract infection | Struvite stone | 6 % |
| Carbonate apatite stone | 3 % | |
| Ammonium hydrogen urate stone | 1 % | |
| Congenital metabolic disorder | Cystine stone | 2 % |
| Dihydroxyadenine stone | 0,1 % | |
| Xanthine Stone | very rare |
Sex ratio: males to females is 2: 1; contrary to previous evidence, there are several studies that the distribution between the sexes is equalizing or increasing at the expense of females over the last decades. Peak incidence: the maximum incidence of urolithiasis is between the ages of 30 and 60. The prevalence (disease incidence) is 5% in Germany, 5-9% in Europe and 12-15% in the USA. The incidence has increased significantly in Western industrialized countries. Urinary stone disease is particularly common in dry and hot regions (10-15 %). Course and prognosis: The size of the stones can vary from a few millimeters to several centimeters. Up to 2 mm in diameter, stones pass spontaneously (by themselves) through urine in the majority of cases. Stones larger than 5-6 mm in diameter rarely pass spontaneously. When the stone does pass, it is often associated with colicky pain and a strong urge to urinate. 50% of patients suffer from recurrent nephrolithiasis (kidney stones). In 10-20% of patients, at least 3 recurrent episodes must be expected. In children, the tendency to recurrence is particularly high. Every primary stone in childhood requires a thorough investigation of the cause! In about 70 % of all cases, children with urinary stones have anatomical abnormalities of the urinary tract. Approximately 70% of all stones analyzed are calcium oxalate stones.Through so-called metaphylaxis (urinary stone prophylaxis), which depends on the type of stone and the cause, the recurrence rate can be reduced below 5%. Basic rules include drinking plenty of fluids (> 2.5 l/day), low animal proteins (protein), low-salt and high-potassium diet, weight normalization and physical activity. Comorbidities (concomitant diseases): Urolithiasis is associated with an increased risk of myocardial infarction (heart attack) (31%). Furthermore, there is an increased risk of urothelial carcinoma (malignant tumors of the transitional tissue (urothelium) lining the urinary tract).
