This ELISA (enzyme-linked immunosorbent assay) kit is produced for the quantitative determination of human anti-CaSR (calcium sensing receptor) autoantibody levels in serum, plasma, tissue extract or other liquid samples. The detection of this autoantibody is clinical useful in the aid of diagnosis of autoimmune sporadic hypoparathyroidism, autoimmune polyendocrinepathy syndrome, acquired hypocalciuric hypercalcemia, as well as other autoimmune parathyroid diseases.

The human calcium-sensing receptor (CaSR) is a 1078 amino acid cell surface protein, which is predominantly expressed in the parathyroid glands and kidney. It is a member of the family of G protein-coupled receptors. The CaSR allows regulation of parathyroid hormone (PTH) secretion and renal tubular calcium reabsorption in response to alterations in extracellular calcium concentrations. Abnormalities of the CaSR are associated with both hypercalcaemic and hypocalcaemic disorders.

The human CaSR gene is located on chromosome 3q21.1 and loss-of-function CaSR mutations have been reported in the hypercalcaemic disorders of familial benign hypocalciuric-hypercalcaemia (FHH, FBH or FBHH) and neonatal severe primary hyperparathyroidism (NSHPT).

CaSR auto-antibodies have been found in FHH patients who did not have loss-of-function CaSR mutations, and in patients with an acquired form (i.e. autoimmune) of hypoparathyroidism. Autoimmune hypoparathyroidism can occur as an isolated clinical abnormality, as part of autoimmune polyendocrinopathy syndrome (APS)-1 or as part of APS-2. APS-1 most commonly comprises mucocutaneous candidiasis, hypoparathyroidism, and Addison’s disease. APS-2 includes two or more of the following: Addison’s disease, Graves’ disease, autoimmune thyroiditis, type 1 diabetes mellitus, primary hypogonadism, myasthenia gravis, or celiac sprue. Studies have demonstrated that CaSR autoantibody is present in about one third of the patients with isolated acquired hypoparathyroidism. On the other hand, it is also reported that some clinical primary hypoparathyroidism can harbor autoantibodies to human CaSR. Therefore, there is a great clinical value of detecting this autoantibdy to assess the autoimmune origin of the disease.

This kit is CE marked for in-vitro diagnostics in Europe.