title: A Case of Vitamin D Deficiency without Elevation of Serum Alkaline Phosphatase in a Carrier of Hypophosphatasia.
abstract: Elevated serum alkaline phosphatase (ALP) is a screening marker for the diagnosis of vitamin D deficiency, which may fail to be diagnosed if serum ALP is not elevated. Here, we describe a case of vitamin D deficiency without elevation of serum ALP. A 1-year-old Japanese girl was referred to our hospital for the evaluation of genu varum. Her serum intact PTH level was elevated, while her serum ALP level was normal. Furthermore, her serum 25-hydroxyvitamin D level was reduced, and her urine phosphoethanolamine (PEA) level was mildly elevated. ALPL gene analysis revealed she was a heterozygous carrier of hypophosphatasia (c.1559delT). Serum intact PTH and urine PEA evaluations were helpful for diagnosing vitamin D deficiency and hypophosphatasia carrier status, respectively. Therefore, the possibility of vitamin D deficiency without elevation of serum ALP should be considered.
authors.affiliation: Department of Pediatrics, Asahikawa Medical College, Asahikawa, Japan.
authors.forename: Kumihiro
authors.initials: K
authors.lastname: Matsuo
authors.forename: Tokuo
authors.initials: T
authors.lastname: Mukai
authors.forename: Akiko
authors.initials: A
authors.lastname: Furuya
authors.forename: Shigeru
authors.initials: S
authors.lastname: Suzuki
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Tanahashi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Azuma
keywords: ALPL; hypophosphatasia; intact PTH; phosphoethanolamine; vitamin D deficiency