Hi Remy! I love Ice Age and your avatar!
Sounds like hemipenes which would indicate a male. He should also have two little pea-like buttons on each side of his vent.
The white portion of his waste is called urates and contains uric acid from protein metabolism. It's normal in reptiles. It's great for determining dehydration, but I have never heard of a link between urates and calcium in normal observation. Perhaps a vet or pathologist could do a urinary analysis and check for composition of crystals, but I don't think that's what you meant. 
Short of getting a lab test done at the vet, getting the right amount of calcium in the diet is sort of guessing game. Proper husbandry is the key, though. Diet is very important: feeding whole foods like rodents and quail/chicks provide bones and vitamins. Calcium supplements that do not contain phosphorous should be used on meals that are ground turkey or organ meats. A high quality tube flourescent UV or mercury vapor bulb helps to manufacture vit D to process the calcium. A basking site of 110-115 will give the tegu a chance to make sure his body is working at optimum temperature.
Laura R (FL)
1.0.0 Colombian Tegu
1.4.0 Argentine B&W Tegu
1.2.0 Red Tegu
1.2.0 B/WxRed Tegu
1.0.0 Green Ameiva (yet another teiid)
7 other lizards
1 little gator
3 FL box turtle
1 Sulcata tortoise
16 snakes
5 fuzzy pets
4 little frogs
a bunch of creepy bugs
and a partridge in a pear tree
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