Brief Answer: Evaluation Detailed Answer: If the weight loss is unintentional, then it merits thorough assessment. I see your doctor has put you on vitamin D2. When I see someone with a level of 11, I generally recommend at least 3000-5000 IU of cholecalciferol which is vitamin D3. The levels must be rechecked in a couple months to see if the supplementation is appropriate. Regarding calcium and parathyroid, it is fairly simple to get one's calcium levels checked by a doctor's order for a BMP (Basic Metabolic Panel). It would be a good idea to get it done along with other routine tests that any doctor would request in order to investigate your weight loss such as CBC TSH Free T4 ESR CMP Sometimes the hydrochlorothiazide can elevate the calcium in the blood.