en Pediatrics Pediatrics Original Article Original Article <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="line-height:14pt"><b><i><span style="color:blue">Background</span></i></b><i><span style="color:blue">:</span></i> The growth and development of children affect biochemical variables. This population-based study was designed to evaluate the reference interval for alkaline phosphatase (ALP) routinely measured in the clinical laboratory.<span style="font-size:9.0pt"></span></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Methods:</span></i></b> For this examination, 873 cases were selected among the healthy children and adolescents aged 1-18 years who referred to the endocrinology clinic of Amirkola Children&#39;s Hospital for growth evaluation. After overnight fasting, early morning blood samples were obtained to measure the ALP level and other biochemical parameters using an automatic biochemical analyzer. Subjects were categorized by age, sex, and body mass index (BMI) values. The age groups were categorized as follows: 1-4 years, 5-8 years, 9-13 years, and 14-18 years.</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Results:</span></i></b> There was a significant difference among the age and sex <span lang="EN">categories</span>; on the contrary, there was no meaningful variation between the two groups categorized by BMI. The reference range for ALP was 474.14-517.71 U/L for children aged 1-4 years, 273.47-871.44 U/L for 5-8 years, 215.04-893.69 U/L for 9-13 years, and 228.9-739.22&thinsp;U/L for 14-18 years. Also, significant positive correlation was found between ALP with length (P=0.000, r=0.134), weight (=0.04, r=0.073), phosphorus (P) (P=0.001, r=0.122), and alanine aminotransferase (SGPT) (P=0.000, r=0.142) respectively.<b><i><span style="color:blue"></span></i></b></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Conclusion</span></i></b><i><span style="color:blue">:</span></i> This project&#39;s data established a reference interval for ALP in healthy children and adolescents, which will prepare a basis for diagnosis and monitoring liver- or bone-related disorders.<b><i><span style="color:#0033cc"></span></i></b></span></span></span><br> &nbsp; Children, Alkaline phosphatase, Reference interval, Biochemistry, Liver function 749 756 http://caspjim.com/browse.php?a_code=A-10-1423-3&slc_lang=en&sid=1 Mehdi Gholami Bahnemiri Mgholami.b@gmail.com 100319475328460039872 100319475328460039872 No Department of Clinical Biochemistry, School of Medicine, Babol University of Medical Sciences, Babol, Iran Shivasadat Mirabedini shiva.mirabedini@live.com 100319475328460039873 100319475328460039873 No Department of Clinical Biochemistry and Medical Genetics, Molecular and Cell Biology Research Center, Faculty of Medicine, Mazandaran University of MedicalSciences, Sari, Iran, Parisa Mohammadi pmohamadi807@gmail.com 100319475328460039874 100319475328460039874 No , Department of Clinical Biochemistry, School of Medicine, Babol University of Medical Sciences, Babol, Iran Haniyeh Barmaki Halehbarmaki1982@gmail.com 100319475328460039875 100319475328460039875 No Department of Clinical Biochemistry, School of Medicine, Urmia University of Medical Sciences, Iran Zohreh Qaffaripour zhr.qaffaripour2020@gmail.com 100319475328460039876 100319475328460039876 No Department of Clinical Biochemistry, School of Medicine, Babol University of Medical Sciences, Babol, Iran Masomeh Rezapour masomeh.rezapour@yahoo.com 100319475328460039877 100319475328460039877 No Traditional Medicine and History of Medical Sciences Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, I.R.Iran. Morteza Alijanpour m.alijanpour@yahoo.com 100319475328460039878 100319475328460039878 Yes Non-Communicable Pediatric Diseasees Research Center, Health Research Institute, Babol, Iran