Calcium in the Urine

Every 40 grams of protein we add to our daily diet, we pee out in extra 50 milligrams of calcium. Meat and eggs have a lot of sulfur containing amino acids that are metabolized into sulfuric acid which the body buffers with calcium. The excess calcium in their urine wasn't coming from their bones, but from what they were eating. But here's the big question: Is that extra calcium in Their urine radioactive or not? And to everyone's surprise, it was radioactive.