They have 3 validity tests to make sure you aren't dilute or using adulterants added to the specimen cup after you pee. Specific gravity and creatinine clearance are for testing dilution, pH for adulterants. Rolaids and Tums help with specific gravity as well as using a sports drink instead of water. Meat is for creatinine clearance.

You have a chance using dilution but I like subbing.

Get a thermometer and do some trial runs subbing.