Vitamin D deficiency (VDD) has been reported from Pakistan in randomly selected healthy volunteers, patients and community females. In all studies a variable proportion (25.9%-31%) of the subjects had secondary hyperparathyroidism, as a compensatory response to VDD. However, a significant number of subjects with VDD show blunted Parathyroid hormone response. This phenomenon has been described in literature as functional hypoparathyroidism. we hypothesized that the presence of secondary hyperparathyroidism in our population could have been due to CaSR polymorphisms. In this cross-sectional...