分かりにくい。
なぜ、「Things」が文の頭にくるのか、余計な「that」までつけて。
とりはらえば、すっきりした英文になり、読者も読みやすいが。

原文
Mayo Clinic Staff
Causes
Most of the time, a high uric acid level occurs when your kidneys don't eliminate uric acid efficiently. Things that may cause this slow-down in the removal of uric acid includ