Prevalence and characteristics of metabolic syndrome in primary hyperparathyroidism

Primary hyperparathyroidism (pHPT) is characterized by an increased frequency of glucose tolerance abnormalities associated with insulin resistance. Few studies evaluated the prevalence of metabolic syndrome (MetS) in pHPT and whether there are differences between asymptomatic pHPT patients and symptomatic ones. Thus, we sought to investigate the prevalence of MetS in pHPT patients in comparison to the prevalence of MetS in Italian population.

We conducted a retrospective chart review of 294 pHPT patients, of these 154 [age (mean ± SD) 58.7 ± 13.3 yr, body mass index 25.6 ± 4.8 kg/m(2); serum calcium (11.3 ± 1.2 mg/dl) 2.8 ± 0.3 mmol/l; PTH 234.8 ± 224.3 ng/l] met the inclusion criteria. A modified National Cholesterol Educational Program (NCEP)/Adult Treatment Panel III (ATP III) definition of the MetS was used. Prevalence of MetS was compared with that reported for the Italian population (Progetto Cuore Study).

The prevalence of the MetS (34/154, 22.1%) was similar to that reported in the general Italian population. Asymptomatic pHPT patients were older (62.1 ± 12.7 vs 56.4 ± 13.2 yr, p<0.008) and showed higher prevalence of MetS than symptomatic ones (30.2% vs 16.5%, p<0.045). Moreover the prevalence of nephrolitiasis or overt bone disease was not different between patients MetS+pHPT compared to MetS-pHPT, whereas femoral bone mineral density (BMD) was higher in MetS+pHPT (p<0.003). In the logistic regression model age and femoral BMD were independent predictors of MetS.

The prevalence of MetS in pHPT is not increased in comparison to the general population, thus, its diagnosis is not an appropriate tool to identify the additional cardiovascular risk related to pHPT. Difference in age affects the increased prevalence of MetS in asymptomatic pHPT patients.