[Evaluation of preoperative diagnosis of primary hyperparathyroidism--special reference to normocalcemic cases]

Since the opening of our clinic 117 years before, we have treated 62 cases of primary hyperparathyroidism (PHPT), among which there were 6 cases (1 male, 5 females) whose calcium levels fell within the normal range. However, in all these cases the serum ionized calcium (Ca++) levels and the serum ionized calcium/calcium ratio (Ca++/Ca ratio) were high. Moreover, in comparing them with hypercalcemic patients (56 cases), the serum Ca++ levels were significantly lower, but the (Ca++/Ca ratio) was significantly higher. Also, the excised weight of 606.1 +/- 520.3 mg was significantly smaller than that of hypercalcemic patients, which was 1,967.9 +/- 2,086.3 mg. Preoperative locations showed significantly lower levels in comparison with hypercalcemic patients by all methods including computed tomography (CT), ultrasonography, scintigraphy, and magnetic resonance imaging (MRI). In normocalcemic patients following parathyroidectomy, although the decrease in serum calcium levels was not significant, the serum Ca++ levels and the Ca++/Ca ratio decreased significantly, so that not only are they useful parameters for preoperative diagnosis of PHPT, but they are also considered necessary and indispensable for observation of the post-operative course and judging therapeutic effects including the operation. Based on our study we concluded that in multiple and recurrent stone formers with normal range of serum Ca levels, regardless of the presence or absence of local diagnosis, if the serum Ca++ level and Ca++/Ca ratio are high, existence of primary hyperparathyroidism must be suspected, and adequate treatments should be instituted promptly.