Clinical effects of parathyroid surgery in normocalcaemic patients with recurrent renal stones.

Among 52 patients with recurrent renal calcium stones submitted for neck exploration 12 had adenomas, 23 hyperplasia and only 17 histologically normal parathyroid glands. These patients were selected for surgery despite a normal mean value of the total serum calcium concentration because they had, in most cases, indirect evidence of parathyroid hyperfunction such as intermittent hypercalcaemia (in 25 of the patients), hypercalciuria or a pathological response to calcium infusion. It is suggested that the patients with adenomas suffered from primary hyperparathyroidism (HPT), which however did not cause persisting hypercalcaemia. It seems likely that parathyroid hyperplasia either was a mild or an early form of primary HPT or secondary to increased calcium losses. In this study, no single laboratory feature could clearly separate the different groups. None of the patients with adenomas formed any new stone during follow-up (2-7 years) and also 40% of those with hyperplasia appeared to experience benefit from surgery. This benefit was more common in those with occasionally raised serum calcium values. In cases with borderline hypercalcaemia HPT is common and is cured by parathyroidectomy. However, in clinical practice the differential diagnosis may be difficult. In cases without firm evidence of HPT a conservative approach is favoured. Thiazides appear to reduce the stone recurrence rate in most euparathyroid patients and will probably help to unmask borderline HPT in recurrent renal stone formers.