ADH1A and Hypercalciuria: Although ADH1 is associated with increased circulating phosphate concentrations and inappropriately low or normal PTH concentrations, this is considered to represent a distinct disease entity from hypoparathyroidism, because affected individuals generally have PTH concentrations that are detectable and may either be below or within the reference range (1, 9, 10), and also a relative hypercalciuria that is characterized by urinary calcium to creatinine ratios that are within or above the reference range (1, 9).