Serum Klotho levels in primary hyperparathyroidism patients before and after parathyroidectomy

Purpose To investigate Klotho level and its association with biochemical indices of primary hyperparathyroidism (PHPT). Methods Fifty PHPT patients and fifty-two age- and body mass index-(BMI) matched healthy control subjects were recruited. In addition, twenty-five PHPT patients underwent parathyroidectomy (PTX) and had 4-month follow-up visits. Intact parathyroid hormone (iPTH), 25-hydroxyvitamin D [25(OH)D], calcium, albumin, corrected calcium, and Klotho levels were determined. Results There was no significant difference in age and BMI between PHPT subjects and controls (p > 0.05). PHPT patients had Klotho levels (15.4 +/- 1.2 ng/mL) about 23% higher compared with those of the controls (11.9 +/- 0.8 ng/mL), but this difference was not significant (p = 0.063). However, postmenopausal PHPT patients had 45% higher Klotho levels (17.6 +/- 1.5 ng/ml) compared with postmenopausal controls (12.1 +/- 0.9 ng/mL,p = 0.008). For postmenopausal subjects, Klotho levels had positive correlation with levels of iPTH (r = 0.25,p = 0.026) and corrected calcium (r = 0.34,p = 0.003), but negative correlation with 25(OH)D (r = -0.23,p = 0.042). After PTX, levels of iPTH and corrected calcium decreased and 25(OH)D levels increased to normal range (p < 0.001). However, there was no significant change in Klotho levels after a 4-month follow-up. Conclusions Serum Klotho levels are higher in postmenopausal PHPT patients than in healthy postmenopausal control subjects. The etiology of elevated Klotho level and its clinical significance requires further investigation.