Renal stones of certain compositions and morphological type may identify patients who should be screened for primary hyperparathyroidism (HPT), according to a new study.

Michel Daudon, MD, of Hôpital Necker-Enfants Malades, Paris, and colleagues compared the composition and morphology of stones from 264 HPT patients (143 male and 121 female) and 24,567 non-HPT stone formers (16,918 male and 7,649 female), which included a subgroup of 1,356 patients (1,049 male and 307 female) with idiopathic hypercalciuria (IH).

Calcium oxalate stones occurred significantly less frequently in patients with HPT than without (51.9% vs. 82.2%), the authors reported in Nephrology Dialysis Transplantation (2011;26:565-572). Whewellite was predominant in 16.3% and 30.2% of HPT and IH patients, respectively, compared with 57.4% in the non-HPT group. Weddellite was predominant in 35.6% and 49.5% of HPT and IH stones, respectively, compared with 24.8% of non-HPT stones, the investigators observed.

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Among calcium phosphate stones, brushite was sevenfold more frequent in HPT than non-HPT patients (14.0% vs. 2.2%), and almost three times as frequent as in IH patients (4.9%), the researchers noted. Carbapatite was significantly more frequent in male patients with HPT compared with non-HPT or IH male patients (23.1% vs. 8.3% and 9.9%, respectively).

Pure type I calculi were markedly less frequent in HPT patients (1.1% vs. 25.3% in non-HPT and 9.1% in IH. The study revealed a high occurrence of IVd calculi in HPT vs. non-HPT and IH patients (14.4%, 2.3%, and 6.3%, respectively), as well as IVa + II stone types (58.3%, 17.2%, and 29.9%, respectively).

“Our results are highly suggestive that HPT induces stones of peculiar composition or morphological type,” the researchers concluded. “Thus, patients who develop calcium-dependent crystalline species such as brushite or mixed weddellite plus carbapatite stones with IVd or IV + II morphology should be especially screened for HPT.”