Endocrine Abstracts

Introduction: Nephrolithiasis and bone disease are the most common complications of primary hyperparathyroidism (PHPT). The aim of this study was to evaluate the relationships between the existence of kidney stones, renal function and bone mineral density (BMD) in PHPT.

Description of methods/design: Biomedical evaluation, BMD measurements and renal ultrasonography were performed in a group of 75 consecutive PHPT patients aged 57.6±12.7 years. The control group consisted of 47 generally healthy volunteers. 30 patients with PHPT were subsequently investigated again one year after effective parathyroidectomy (PTX).

Results: Osteoporosis occurred in 72% and nephrolithiasis or nephrocalcinosis in 60% of patients with PHPT. There was no significant difference in glomerular filtration rate (GFR), parathormone, calcemia, calciuria, serum vitamin 25(OH)D, bone turnover markers and BMD between patients with and without renal stones. However, in patients with nephrolithiasis serum 1,25(OH)₂D concentration was higher (P=0.019), phosphate concentration was lower (P=0.009) and only a slight tendency to a higher GFR and serum osteocalcin was observed.

The mean GFR of the whole group (88.3±29.3 ml/min/1.73 m²) was lower (P=0.019) than in controls (104.8±25.1). 84% of the PHPT patients displayed a GFR greater than 60 ml/min/1.73 m² and thus above the recommended indication level for parathyroidectomy. However, even within this subgroup GFR was lower than in controls. GFR did not change following parthyroidectomy, although the severity of nephrolithiasis has decreased in many patients.

Conclusions: Nephrolithiasis does not seem to be the only cause of GFR reduction in PHPT. Since there is no certainty that the reduction in GFR in symptomatic PHPT is reversible after PTX, decisions regarding surgery should not be delayed even in mild cases. There is no clear correlation between BMD and the formation of kidney stones.