title: Prevalence of transient hyperphosphatasemia among healthy infants and toddlers.
abstract: OBJECTIVE
  To describe the prevalence and clinical characteristics of transient hyperphosphatasemia (TH) in a cohort of healthy infants and toddlers.
  
  
  METHODS
  We performed a secondary data analysis of healthy infants and toddlers enrolled in a study examining the epidemiology of vitamin D deficiency. From 2005 to 2007, children aged 8 to 24 months were enrolled during well-child visits at an urban primary care pediatric clinic. At enrollment, we collected data regarding sociodemographic and clinical characteristics. We measured serum levels of alkaline phosphatase (AP), 25-hydroxyvitamin D, parathyroid hormone (PTH), calcium, magnesium, and phosphorus. We placed participants into 1 of 3 categories on the basis of serum AP levels: normal (AP: 110-400 U/L), intermediate (AP: >400 to 1000 U/L), and TH (AP: >1000 U/L). We used Fisher's exact test and analysis of variance to evaluate differences in characteristics among the 3 groups.
  
  
  RESULTS
  Nine (2.8%) of 316 children had an AP level of >1000 U/L (mean: 2165 U/L). Sixteen children (5.1%) had an intermediate serum AP level (mean: 544 U/L). Mean weight-for-age, length-for-age, and weight-for-length z scores were similar across all 3 AP groups. Compared with the 291 children without TH, children in the intermediate AP and TH groups had similar mean serum levels of 25-hydroxyvitamin D, PTH, calcium, magnesium, and phosphorus.
  
  
  CONCLUSIONS
  TH seems to be a relatively common condition among healthy infants and toddlers. TH was not associated with anthropometric measures, vitamin D status, PTH, or serum minerals. Recognition of this benign condition is important to avoid unnecessary investigations.
authors.affiliation: Division of Gastroenterology, Children's Hospital Boston, Boston, Massachusetts 02115, USA. susanna.huh@childrens.harvard.edu
authors.forename: Susanna Y
authors.initials: SY
authors.lastname: Huh
authors.forename: Henry A
authors.initials: HA
authors.lastname: Feldman
authors.forename: Joanne E
authors.initials: JE
authors.lastname: Cox
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Gordon
mesh_terms: D000469:Alkaline Phosphatase / Q000097:blood*; D000886:Anthropometry; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood; D011446:Prospective Studies; D012016:Reference Values; D012621:Seasons; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D000469:Alkaline Phosphatase