How does the body keep blood calcium constant regardless of intake?

76 year-old has dermatochalasis on bilateral upper eyelids. a blepharoplasty will be performed on the eyelids. a lower incision line was marked at approximately 5 mm above the lid margin along the crease. then using a pinch test with forceps the amount of skin to be resected was determined and marked. an elliptical incision was performed on the left eyelid and the skin was excised. in a similar fashion the same procedure was performed on the right eye. the wounds were closed with sutures. the correct cpt® code(s) is/are? a. 15822, 15823-51b. 15823-50c. 15822-50d. 15820-lt, 15820-rt