Urolithiasis(urinary calculus) refers to the formation of calculi in urinary system. In the light of locations of calculi, it can be classified into renal calculus, ureteral calculus, cystic calculus and urethral calculus. Clinically, it is characterized by dull pain in the loins and abdomen, hematuria, cloudy urine, acute obstructive oliguria, anuresis, even renal colic and acute renal failure.

According to its clinical manifestations, the disease pertains to "sha lin" (sandy stranguria), "shi lin"(stony stranguria), "xue lin" (bloody stranguria), "yao tong" (lumbago) in TCM. It usually results from external invasion of damp heat, or addiction to pungent, greasy and sweet food, either of which results in the retention of damp heat in the bladder, causing the formation of stones. The impaired parts are the bladder and kidneys, often involving the spleen and liver.

The pathogenesis of the disease is primarily the retention of damp heat in the lower energizer and obstruction of qi activities in the bladder. In prolonged cases, pathogenic damp blocks yang qi, pathogenic heat turns into fire and further injures yin, or yin injures qi, thus leading to deficiency of both the spleen and kidneys. The syndrome is then transformed from the excess one to the deficiency one, or a combination of both.