After a parathyroidectomy, what calcium problems will one have?

Depends: Of one or two glands are removed, probably nothing, if all removed you will need life long calcium replacement and vitamin d therapy.

Variable: If only 1 or 2 glands are removed, usually none unless the hyperapara was long-standing and severe (then you would have to take calcium for awhile). If 3 1/2 glands are removed or all 4 (with reimplantation) then the calcium will fall at least for a short time and your levels will need to be monitored closely.

Parathyroidectomy: There are 3 options: normal, high, or low. Normal is ideal, the surgery was a success. High means the surgery was a failure or there is another cause, not from the parathyroids. Low can come from parathyroid damage from an aggressive surgery or hungry bone syndrome.