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Transient hyperphosphatasemia of infancy and childhood. A study of serum alkaline phosphatase by electrofocusing
J Griffiths1, A Vernocchi, E Simoni
1Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, USA.
Insights
Transient hyperphosphatasemia in children is linked to infections or failure to thrive. Alkaline phosphatase (ALP) isoenzyme patterns reveal infection targets or nutritional status, aiding diagnosis.
Area of Science:
- Biochemistry
- Pediatrics
- Clinical Chemistry
Background:
- Transient hyperphosphatasemia is a condition of elevated serum alkaline phosphatase (ALP) in infants and children.
- Understanding the etiology of elevated ALP is crucial for accurate diagnosis and management.
Purpose of the Study:
- To evaluate serum alkaline phosphatase (ALP) isoenzymes using electrofocusing in transient hyperphosphatasemia of infancy and childhood.
- To differentiate causes of elevated ALP in pediatric patients.
Main Methods:
- A randomized study involving 135 infants and children with markedly increased total ALP activity.
- Serum samples were analyzed using a sensitive electrofocusing technique.
- International reference enzyme laboratories participated in the study.
Main Results:
- Three patient groups were identified based on ALP isoenzyme patterns.
- Group 1: Healthy children with viral/protozoal infections; ALP reflected target organs.
- Group 2: Failure to thrive with superimposed infection; ALP reflected infection and primary disease.
- Group 3: Failure to thrive (nonorganic/caloric deficit) without infection; lower ALP of hepatic/bone origin, decreased with nutritional improvement.
Conclusions:
- ALP isoenzyme patterns can help elucidate the pathogenesis of hyperphosphatasemia in children.
- Further research is needed to understand why only a subset of children exhibit such high ALP levels in response to infection.
Objective:
To evaluate serum alkaline phosphatase (ALP) isoenzymes, using a sensitive electrofocusing technique, in transient hyperphosphatasemia of infancy and childhood.
Design:
Randomized study of infants and children who provided serum samples when an unusual magnitude of total ALP activity was noted.
Setting:
Reference enzyme laboratories in Gorizia and Bergamo (Italy) and in Charleston, SC (USA).
Patients:
A total of 135 infants and children noted to have markedly increased total ALP activity.
Main Outcome Measures:
Recognition of the disease pathogenesis with appropriate treatment instituted.
Results:
Three groups of patients were identified: (1) previously healthy patients who showed additional laboratory evidence of viral and protozoal infection, in whom the ALP isoenzyme pattern reflected the primary target organ(s) of the infection; (2) patients with clinical evidence of failure to thrive due to preexisting disease, along with a superimposed infection (the ALP isoenzyme pattern reflected the specific infection and fractions associated with the primary disease); and (3) patients exhibiting failure to thrive (nonorganic or caloric deficit) who did not show evidence of infection. The total ALP in the third group was lower than in the other groups, was of hepatic and bone origin, and decreased when a positive caloric balance was established.
Conclusion:
We examined several mechanisms to explain the hyperphosphatasemia. A perplexing question remains: Will a small group of infants and children respond to infection with this magnitude of ALP activity? Conversely, do all children respond, but a small number fortuitously undergo laboratory measurements that include ALP levels?