[Clinical Value of Renal Phosphorus Threshold in the Diagnosis and Treatment X-linked Hypophosphatemic Rickets in Children]

Overview

Journal Zhongguo Dang Dai Er Ke Za Zhi

Specialty Pediatrics

Date 2024 Sep 13

PMID 39267507

Authors

Jia-Qi Tao

Ying Chen

Affiliations

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Abstract

Objectives: To explore the clinical value of the renal phosphorus threshold (ratio of tubular maximum reabsorption of phosphate to glomerular filtration rate, TmP/GFR) in the diagnosis and treatment of children with X-linked hypophosphatemic rickets (XLH).

Methods: A retrospective study was conducted, including 83 children diagnosed with XLH at Children's Hospital of Nanjing Medical University from January 2010 to January 2023. Initial diagnosis and follow-up data were collected to investigate the correlation of TmP/GFR with the severity of rickets, calcium and phosphorus metabolism indicators, and the dosage of phosphate treatment. Children were divided into two groups based on the occurrence of renal calcification: the renal calcification group (=47) and the non-renal calcification group (=36). Clinical data between the two groups were compared. Multivariate logistic regression analysis was used to identify factors influencing renal calcification in XLH children. The predictive value of TmP/GFR for renal calcification in XLH children was evaluated using receiver operating characteristic (ROC) curves.

Results: In the 83 XLH children, the initial TmP/GFR was (0.78±0.21) mmol/L, with significant individual variation (range: 0.28-1.24 mmol/L). TmP/GFR showed no significant correlation with the severity of rickets (>0.05). Parathyroid hormone was negatively correlated with TmP/GFR (=-0.020, =0.008), while blood phosphorus (=0.384, <0.001), blood calcium (=0.251, <0.001), and 25-hydroxyvitamin D (=0.179, <0.001) were positively correlated with TmP/GFR. No significant correlation was found between TmP/GFR and alkaline phosphatase (=-0.002, =0.960) or phosphate treatment dosage (=0.012, =0.800). Blood calcium and TmP/GFR levels were significantly lower in the renal calcification group than in the non-renal calcification group (<0.05), while parathyroid hormone and urine calcium levels were significantly higher in the renal calcification group (<0.05). Multivariate logistic regression analysis indicated that TmP/GFR and urine calcium levels were closely associated with renal calcification in XLH children (<0.05). ROC curve analysis revealed that the areas under the curve for TmP/GFR, urine calcium, and their combined detection predicting renal calcification in XLH children were 0.696, 0.679, and 0.761, respectively.

Conclusions: TmP/GFR may serve as an important diagnostic indicator for pediatric XLH; however, it does not reflect the severity or activity of rickets and cannot be used to judge the efficacy of traditional treatment. Urine calcium and TmP/GFR are valuable predictors for renal calcification in XLH children.

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