Calcitriol (Vitamin D3) and excretion of calcium

Because my remaining parathyroids barely function (had an adenoma removed about 13 months ago), I take large amounts of calcium.  Specifically, on a daily basis I take 1400 mg. calcium citrate plus 200 mg.  calcium carbonate in my multiple vitamin/mineral supplement.  I also take .25 mcg. Calcitriol every other day to aid in the absorption of the calcium.  
My blood serum levels of calcium are at the low end of the range, but my levels of urinary calcium excretion are too high. I have been doing research on Vitamin D and I can't determine whether I should be taking more or less of Vitamin D in order to help decrease the amount of calcium that is being excreted in the urine.  Calcium homeostasis is confusing to understand.
I did find one study done in 2008 which showed that bicarbonate, but not potassium, had a favoarable effect on bone resorption and calcium excretion.
Could you tell me, please, what might be done to limit the calcium I'm losing.
Thank you,
Mary

[Renee Radenberg]

Calcium is maintained in our body by hormones (parathyroid hormone, vitamin D, and cilcitonin). You stated your parathyroid is barely functioning. It is recommended that you take calcium supplement with food so you maximize the absorption of the calcium with the stomach acid production of food in the stomach. Calcium carbonate supplementation is absorbed the best into our bodies. Calcium you consume is not 100% absorbed and the rest will be excreted. Calcium is in all dairy products: cheese, yogurt, pudding, and ice cream. Other sources are: Orange juice fortified with calcium, Tofu, Almonds, Kale, Beans, Broccoli, and Eggs. If this still does not help, suggest seeing a Thyroidologist to help you.