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Parameters of evaluation and correlation of renal phosphate handling and of parathyroid function in children
H Stark1, B Eisenstein, M Davidovits
1Pediatric Nephrology Unit, Beilinson, Medical Center, Petah Tiqva, Israel.
Insights
This study establishes normal parathyroid (PT) function values in children, finding lower carboxyl terminal PTH and urinary cAMP (UcAMP) than adults. A correlation between UcAMP and tubular phosphate reabsorption was identified.
Area of Science:
- Pediatric Endocrinology
- Renal Physiology
Background:
- Parathyroid (PT) hormone and its metabolites play a crucial role in calcium and phosphate homeostasis.
- Establishing normative data for PT function in pediatric populations is essential for diagnosing related disorders.
Purpose of the Study:
- To determine normal reference ranges for parathyroid hormone (PTH) and urinary cyclic adenosine monophosphate (cAMP) in children.
- To investigate the relationship between PT function parameters and tubular phosphate (P) reabsorption in pediatric subjects.
Main Methods:
- Measurement of carboxyl terminal PTH and urinary cAMP (UcAMP) levels in a pediatric cohort.
- Analysis of tubular phosphate (P) reabsorption (TP) in relation to UcAMP.
- Statistical correlation analysis to establish relationships between parameters.
Main Results:
- Pediatric values for carboxyl terminal PTH and UcAMP were significantly lower compared to adult reference ranges.
- A significant negative correlation was observed between UcAMP and tubular phosphate reabsorption (TP).
- The established equation (TP = 5.5 - 0.5 x UcAMP mg/dl GF) quantifies this relationship.
Conclusions:
- The findings provide normative data for PT function in childhood.
- The correlation identified allows for the differentiation between primary tubular defects and parathyroid activity in renal phosphate handling disorders.
Abstract:
The aim of the study was to establish normal values for parameters of parathyroid (PT) function in childhood and to examine whether a correlation could be found between these parameters and tubular phosphate (P) reabsorption. Values for PTH (carboxyl terminal) and urinary cAMP (UcAMP) throughout childhood were found to be significantly lower than in adults, with mean values of 0.3 ng/ml (30 pmol/l) and 1.96 nmol/dl glomerular filtrate (GF) respectively. A significant correlation was found between UcAMP and tubular P reabsorption (TP), expressed by the equation: TP = 5.5-(0.5 x UcAMP) mg/dl GF (= 1.78-(0.16 x UcAMP) mmol/dl GF, with a scatter of 10.6 mg/dl around the mean (+/- 1 SD). These data appear to permit the evaluation of primary tubular components in patients with defects of renal P handling, as opposed to those related to PT activity.