Normocalcemic hyperparathyroidism and insulin resistance.

OBJECTIVE

To determine whether insulin resistance (IR) accompanies normocalcemic primary hyperparathyroidism (NCPHP).

METHODS

Twenty-five patients with NCPHP and 25 age-, sex-, and body mass index (BMI)-matched controls were included the study. Patients were diagnosed NCPHP if their serum calcium (Ca) concentrations and ionized serum Ca levels were in the normal range but parathyroid hormone (PTH) levels were inappropriately and persistently high. Subjects with 25-hydroxyvitamin D (25[OH]D) levels ≥20 ng/dL were included in the study. The upper limit of PTH was calculated using a nomogram for each subject. Patients and controls underwent a standard 75-gram oral glucose tolerance test (OGTT). IR was assessed by the homeostasis model assessment (HOMA-IR) and insulin sensitivity index (ISogtt).

RESULTS

There were no differences between the demographic features of patients with NCPHP and the control group. IR frequency was not different between groups (P = .14). HOMA-IR was higher and ISogtt was lower in patients with NCPHP than the control group, but the differences were not significant (P = .17 and P = .22, respectively). We did not find any correlation between PTH and glucose metabolism markers (HOMA-IR, ISogtt, glycated hemoglobin [HbA1c], and BMI) in either of the groups.

CONCLUSION

The results of this study indicate that IR is not more common in patients with NCPHP, and PTH is not related to ISogtt or HOMA-IR.