title: Transient hyperphosphatasaemia: an important condition to recognize.
abstract: OBJECTIVE
  To investigate the prevalence and aetiology of transient hyperphosphatasaemia (TH) of infancy and childhood in a tertiary referral paediatric hospital.
  
  
  METHODS
  Retrospective review of the medical records of patients with measured plasma alkaline phosphatase (ALP) activity of over 1000 U/L.
  
  
  RESULTS
  Over a period of 1 year, 68 children with plasma ALP activity of over 1000 U/L were identified. The main aetiologies were liver disease (34 cases), TH (21 cases) and bone disease (11 cases). The mean age of children with TH was 1 year and 5 months and there was a male predominance (3:1). The children with liver and bone disease were older (mean ages of 6 years, 6 months and 5 years, 1 month, respectively) and there was no gender difference. The mean plasma ALP activity for the children with TH was 3395 U/L, and in those patients in whom ALP activity was measured sequentially, mean ALP returned to within normal limits after an average of 70 days. There was a seasonal predominance of TH cases, with a significant number presenting during the winter, suggesting a viral aetiology. The most common clinical presentation of children with TH was gastroenteritis (8/21).
  
  
  CONCLUSIONS
  Cases of TH can be clearly identified by considering the age of the patient and by excluding other known causes of markedly elevated ALP, in particular liver or bone disease. Using these exclusion criteria, the prevalence of TH was found to be high. Early recognition of this benign condition may prevent misdiagnosis and further unnecessary investigations.
authors.affiliation: Department of Paediatrics and Child Health, Royal Alexandra Hospital for Children, Westmead, New South Wales, Australia.
authors.forename: A J
authors.initials: AJ
authors.lastname: Carroll
authors.forename: J C
authors.initials: JC
authors.lastname: Coakley
mesh_terms: D000293:Adolescent; D000469:Alkaline Phosphatase / Q000097:blood*; D001847:Bone Diseases / Q000201:enzymology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008107:Liver Diseases / Q000201:enzymology* / Q000453:epidemiology; D008297:Male; D009517:New South Wales / Q000453:epidemiology; D015995:Prevalence; D012189:Retrospective Studies
chemical_list: D000469:Alkaline Phosphatase