My son has suffered from multiple fractures. His Vitamin D levels have remained below 20 despite giving him supplements and making him go out in the sun for 30 minutes a day. He has been worked up for many metabolic bone diseases including OI, but all are negative. We recently took him to ER to find out that he had a kidney stone. His GPt was high, K was low along with the other blood tests that I am more familiar with...High sed rate, high platelets, high neutrophils, low lymphs. I'm not sure what the GPT is or how connected the kidney stone is to the fractures. (He fractured right tib/fib, both ulnas, left fib. verteb. compression fracture, and 3 right metacarpals)