Cut off Value for Parathormone Level in Children with Vitamin D Deficiency

Background: When serum level of 25-hydroxy vitamin D [25(OH) D] decreases, intact Parathormone (iPTH) level increases compensatory. This study aimed to determine the cut off value for iPTH level in 2-14-year-old children with vitamin D (VD) deficiency. Methods: This cross-sectional study was performed on 153 children aged 2-14 years old who referred to the endocrinology clinic of Amirkola Children s Hospital for growth assessment. Census sampling was conducted from January 2016 to June 2017 according to the eligibility criteria including height and weight above the percentile of 3% of growth charts and normal serum of calcium level ( gt;8.5 mg/dl). Laboratory parameters such as serum calcium, 25(OH) D and iPTH levels were assessed. The children were divided into three groups based on serum levels of 25(OH) D as mild, moderate and severe VD deficiency. The Receiver Operating Characteristic (ROC) curve was used to analyze the cut-off point of iPTH and 25(OH) D. P-Value lt; 0.05 was considered significant. Results: The mean VD and iPTH levels in children were 11.8 ± 4.59 ng/ml and 28.3 ± 13.3 pg/ml, respectively. At the iPTH serum level of 23.5 pg/ml, with a sensitivity of 66.1%, there was a possibility of moderate to severe VD deficiency. In the severe deficiency group, at the iPTH serum level of 23.5 pg/ml and above, with a sensitivity of 78.9%, there was a possibility of severe VD deficiency. The cut-off point of 25(OH) D and iPTH, at the serum VD level ≤10 ng/ml were determined. Conclusions: The results of the present study showed that the cut-off value for iPTH in children with VD deficiency is serum level of 25OHD≤10ng/ml.