If we take a simplistic view you are right.
Elevated PTH and serum calcium levels indicate primary hyperparathyroidism.
Vitamin D levels are depressed in patients with primary hyperparathyroidism and may not elevate until the cause is eliminated.
In that case it would not be advisable to load you with high dose of Vitamin D before removal of parathyroid.
But there are other confounding factors.
Certain drugs like thiazide diuretics and lithium may also cause a picture like primary hyperparathyroidism and this confounding factor needs to be considered.
A condition known as familial hypocalciuric hypercalcemia (FHH) can mimic primary hyperparathyroidism and should be eliminated before considering surgery because FHH does not need surgical treatment.
A 24-hour urine calcium and creatinine test are done to rule out this condition.
National Institutes of Health (NIH) consensus panel has come up with the guidelines for recommending surgery in patients who are asymptomatic.
According to these guidelines following set of patients may be offered surgery
Serum calcium level more than 1.0 mg/dL above the upper limit of normal
Marked hypercalciuria (> 400 mg/day) or renal stones
Creatinine clearance less than 30% of normal
Marked bone density reduction with a T-score lower than 2.5 at any site
Age less than 50 years (if the problem is left untreated, many of these younger patients eventually develop complications of primary hyperparathyroidism)
- A patient who requests surgery or a patient for whom surveillance and follow-up are difficult or impossible.
Patients with minor symptoms have to depend upon the experience of the surgeon in determining if surgery would eventually be beneficial.
Having said that I would recommend that you seek another opinion and have a complete workup before deciding about surgical treatment.