We stress the importance of a complete biochemical investigation of the calcium-phosphate metabolism to recognize typical biochemical alterations associated with this condition (hypocalcaemia, hyperphosphataemia with increased phosphate tubular reabsorption and elevated PTH levels) in spite of a phenotypic aspect that often lacks the presence of all the peculiar clinical features of Albright hereditary osteodistrophy. This evidence concerns the gene PTH and Hypocalcemia.