Can a renal function lab test detect if a kidney stone is developing?

No. There is no specific lab test that detects kidney stones. Only imaging of the kidneys can definitely detect if you have a kidney stone. The renal function test and urine test can help determine the cause of the kidney stones. Once knowing the origin, you can be placed on a specific diet or medicine to prevent the stones from re-appearing.
No. A renal function lab would be unlikely to show a developing kidney stones. Most kidney stones are diagnosed because of severe pain in the flank radiating down to the groin. They can be seen on xray, CT scan or sometimes ultrasound. Blood tests are usually normal.