I have a history of calcium oxalate kid stones. Not severe. I tried medifast and did a 24 hr urine for uric acid. It was high around 1200. Blood uric acid is normal. Aren't my kid doing their job?

Hyperexcreator uric. Your evaluation suggests you may need treatment for your over excretion of uric acid as it may be related to the kidney stones. The calcium oxalate stones may have a central nidus of uric acid and thus the reason to treat this.
Diet Sprite. Here's any easy tip. Drink a lot of diet sprite. Why diet? --no calories. Why sprite? Cheap way to get citrates and citric acid which decrease calcium and oxalate supersaturation. Plus the volume increases urine output. Several glasses a day can help. Other rich in citrate drinks can also be used.