The human bioactive Sclerostin ELISA is for determination of bioactive sclerostin in serum, plasma.
- Sensitivity: LOD: LOD: (0 pmol/l + 3 SD): 1.9 pmol/l; LLOQ: 1.3 pmol/l
- Dynamic Range: 62.5 to 320 pmol/l
- Sample Size: 20 µl
- Sample Type: Serum, EDTA plasma, and citrate plasma
- Incubation: 4 hours
Sclerostin is a 22.5 kDa secreted glycoprotein that functions as a potent inhibitor of Wnt signaling. It acts by binding to the Wnt-coreceptor LRP5/6 thus inhibiting bone formation by regulating osteoblast function and promoting osteoblast apoptosis. The Sclerostin protein consists of two flexible N- and C-terminal arms and a cystine-knot with three loops, whereas the second loop binds to the LRP5/6 complex (3,4). Sclerostin is classically considered to be a monomeric protein, but data from Hernandez and colleagues (5) postulate that circulating sclerostin has a dimeric configuration.
In addition, it is not yet well documented if also Sclerostin fragments circulate, but the comparison of different Sclerostin ELISAs suggest that fragments exist as well.As the epitope of the monoclonal capture antibody utilized in the bioactive Sclerostin ELISA is located in loop 2, the binding region to the LRP 5/6 complex, all Sclerostin molecules (including potential fragments) containing this receptor binding region can be detected.Sclerostin is nearly exclusively produced in osteocytes. Mutations in the Sclerostin (SOST) gene can cause sclerosteosis and van Buchem disease which are bone dysplasia disorders characterized by progressive skeletal overgrowth.
Sclerostin levels are altered in response to hormonal stimuli or due to pathophysiological conditions. Sclerostin concentrations are increased in disorders such as hypoparathyroidism, Paget’s disease, multiple myeloma and in cancer induced bone diseases. Sclerostin levels are decreased in primary hyperparathyroidism, as well as by the mechanical stimulation of bone. Several studies have found a positive association between sclerostin and bone mineral density.
Sclerostin levels in chronic kidney disease (CKD) patients are up to 4-fold increased compared to patients without CKD and increase with CKD stage and declining kidney function. In CKD patients, renal elimination of sclerostin increases with decreasing renal function. In dialysis patients, sclerostin is an independent predictor of bone loss. Numerous studies have shown that serum sclerostin levels are also associated with cardiovascular events.
A monoclonal sclerostin antibody for the treatment of osteoporosis is currently undergoing clinical trials.