Renal stones are formed by precipitation in crystalline or granular form of acids in the urine. Stones may be made of uric acid, calcium oxalate or calcium phosphate. The pain usually starts in one loin and radiates to the lateral abdominal region and then down to the groin. However, it may also start in the lateral abdominal region and radiate to the back. The pain, due to the violent contraction of kidney-pelvis and ureter, is sudden and very severe. It persists for 12–24 hours and is accompanied by frequency and difficulty of micturition, nausea, vomiting, sweating and sometimes shock.
From a Chinese perspective, this usually manifests with symptoms of Damp Heat and, in chronic conditions, frequently occurs against a background of Kidney-Yin deficiency. When Damp Heat is retained for a long time, Heat evaporates fluids, condenses Dampness and precipitates it to form stones or sand. Stone Urinary Syndrome is always by definition a Full condition (although, of course the Dampness may occur against a background of Spleen deficiency).