A Comparison between Silent and Symptomatic Renal Stones in Primary Hyperparathyroidism

Nephrolithiasis is a common complication of primary hyperparathyroidism (PHPT), and in a subgroup of patients stones are clinically silent. Patients with silent and symptomatic stones may differ biochemically. There is a scarcity of data available comparing patients with silent and symptomatic renal stones in PHPT.

To characterize patients with PHPT with nephrolithiais and to compare patients with silent and symptomatic stones.

We reviewed clinical data of 186 patients with PHPT managed at our center from January 1996 to December 2017. Silent renal stones were defined as ultrasonography finding of renal stones without symptoms. Symptomatic renal stones were defined as those with symptoms or a history of graveluria or any procedure for nephrolithiasis. A 5-mm diameter was set as the cut-off between micro- and macrolithiasis. We compared those with (n = 95) and without (n = 91) stones, and, among stone formers, those with symptoms (n = 66) and silent (n = 29) were compared.

There was no significant difference between stone formers and nonstone formers with respect to biochemical parameters. Patients with silent renal stones had significantly lower serum calcium and higher phosphate, than those with symptomatic stones. Most (75%) patients with silent renal stones had microlithiais, while only a fifth (22%) with symptomatic renal stones had microlithiasis.

Nephrolithiasis is a common complication of PHPT. Most patients with silent renal stones had microlithiasis and biochemical features of less severe disease. Patients with silent renal stones may represent early mild stage of PHPT.