Serum alkaline phosphatase (ALP) is in Paget's disease elevated but calcium, parathyroid hormone, 25-hydroxyvitamin D, and 1,25-dihydroxyvitamin D levels are normal. Cranial expansion may narrow cranial foramens and cause neurologic complications including hearing loss from cochlear nerve damage from temporal bone involvement. Skull radiographs reveal regions of "cotton wool," or osteoporosis circumscripta, thickening of diploic areas, and enlargement and sclerosis of a poion or all of one or more skull bones. Veebral coical thickening of the superior and inferior end plates creates a "picture frame" veebra. Diffuse radiodense enlargement of a veebra is referred to as "ivory veebra." Ref: Favus M.J., Vokes T.J. (2012). Chapter 355. Paget's Disease and Other Dysplasias of Bone. In D.L. Longo, A.S. Fauci, D.L. Kasper, S.L. Hauser, J.L. Jameson, J. Loscalzo (Eds), Harrison's Principles of Internal Medicine, 18e.