Introduction: Patients with primary hyperparathyroidism (pHPT) run an increased risk of death, and in some studies cardiovascular diseases were inversely related to urine osmolality.
Aim: Evaluate the renal concentration capacity in patients with mild and severe pHPT, and its changes after surgery for pHPT and during medical management and monitoring.
Materials and methods: The study included 77 patients (median age 57 (52;61)) with pHPT, group contained patients with mild form (n=23).
Osmolality index was calculated as urine osmolality to blood osmolality ratio. Renal concentration capacity impairment was diagnosed with osmolality index <2. Changes in osmolality index were evaluated in 13 patients after surgery for pHPT and in 13 patients during medical management and monitoring. Follow-up period was up to 24 months.
Results: Osmolality index in patients with pHPT was low with median 1.64 (1.36; 2.08). We found a high prevalence of renal concentration capacity impairment in patients with pHPT, that was 72%. Both patients with mild and severe pHPT had similar prevalence. Urine osmolality was Me 0.475 (0.39; 0.588) osm/kg. In patients with renal concentration capacity impairment PTH level was significantly higher, than in patients with normal urine osmolality (P=0.039).
Changes in renal concentration capacity in long-term period after surgery for pHPT were characterized by increase of osmolality index, also in patients with mild form, (initially 1.75 (1.4; 2.14), after surgery 2.38 (1.84; 2.54)), changing Me was +12.4% in 624 months (P=0.012).
No significant changes in osmolality index were observed during medical management and monitoring, the same data found for patients with mild form pHPT.
Conclusions: Renal concentration capacity impairment is common in mild and severe pHPT. Renal concentration capacity is restorated after surgery for pHPT. The findings of this study add cause for measurement of urine osmolality or osmolality index in all patients with pHPT.