<s>[INST] My son was diagnosed with a renal stone measuring 5x4x3 mm with moderate hydronephrosis and there is perinephric and peri urethral stranding what does that mean? And he also had a 2mm calculus in the midsole calyx of the left kidney going to urologist tomorrow but should I be worried about his kidney? [/INST] Hi. Welcome to Chat Doctor. Normally, urine contains many dissolved substances. At times, some materials may become concentrated in the urine and form solid crystals. These crystals can lead to the development of stones. Stones formed in the kidney are called kidney stones.  Ureteral stone is a kidney stone that has left the kidney and moved down into the ureter. Surgical treatment of stones include Shock Wave Lithography (ESL), Ureteroscopy (URS), Percutaneous nephrolithotomy (PNL) and Open Surgery. In your case stones are not so big and mild to moderate HY Chat Doctor.  If your son kidney function is good your doctor may suggest conservative treatment. If stones resist coming in urine, they might suggest ESL. But do remember this your urologist only can decide after complete examination of your son. There is no need to be tensed by this, and it is easily treatable condition. Kidneys come back to their normal size gradually once the root cause is treated. Tell your son to  </s>