Endocrine Abstracts

The ‘canonical’ Wnt/β-catenin pathway plays an important role in the development and patterning of bone. Dkk1 (Dickkopf1) and sclerostin are competitive soluble inhibitors of this pathway. Serum sclerostin is decreased in patients with primary hyperparathyroidism (PHPT) compared to the healthy subjects and hypoparathyroid (HypoPT) patients. No data are currently available on Dkk1 serum level in PHPT.

We evaluated serum Dkk1 and sclerostin levels in 42 (10 males and 32 females) patients with sporadic PHPT, 16 (9 males and 7 females) patients with HypoPT and 36 (10 males and 26 females) healthy controls.

Serum sclerostin and Dkk1 were measured using an ELISA assay (Biomedica Medizinprodukte GmBH & Co KG., Germany). All measurements were performed in a single assay. Bone mineral density at lumbar spine, hip and third distal non dominant forearm was measured in patients with PHPT by DXA (QDR-Hologic).

Serum sclerostin concentration in PHPT patients (15.8±7.0 pmol/l) was lower than in controls (20.4±7.9 pmol/l, P=0.0052), whereas no difference was found between PHPT and HypoPT patients (18.4±8.1 pmol/l, P=0.198) and between HypoPT patients and controls (P=0.382). Serum Dkk1 concentration was lower in PHPT (6.2±2.6 pmol/l, P<0.0001) and HypoPT patients (6.3±2.3 pmol/l, P=0.0026) compared to healthy subjects (9.2±3.6 pmol/l), whereas no difference was found between PHPT and HypoPT patients (P=0.940). In PHPT patients, there was a negative correlation between serum PTH and sclerostin (r=0.342, P=0.025), and no correlation between PTH and Dkk1 level. No correlation was found between sclerostin, Dkk1 and bone turnover markers, bone density.

In conclusion, serum levels of sclerostin and Dkk1 are decreased in patients with PHPT compared to controls; no definitive conclusion can be reached in patients with HypoPT because of the limited number of patients.