ESPN 54th Annual Meeting

ESPN 2022


 
RENAL FUNCTION IN CHILDREN WITH TUBEROUS SCLEROSIS COMPLEX
PIOTR SKRZYPCZYK 1 ANNA MARIA WABIK 1 ANNA DEJA 1 MICHAL SZYSZKA 2 PRZEMYSLAW BOMBINSKI 4 ALEKSANDRA JAKIMOW-KOSTRZEWA 4 MICHAL BRZEWSKI 4 SERGIUSZ JOZWIAK 3

1- DEPARTMENT OF PEDIATRICS AND NEPHROLOGY, MEDICAL UNIVERSITY OF WARSAW
2- DEPARTMENT OF PEDIATRICS AND NEPHROLOGY, DOCTORAL SCHOOL, MEDICAL UNIVERSITY OF WARSAW
3- DEPARTMENT OF PEDIATRIC NEUROLOGY, MEDICAL UNIVERSITY OF WARSAW
4- DEPARTMENT OF PEDIATRIC RADIOLOGY, MEDICAL UNIVERSITY OF WARSAW
 
Introduction:

Renal lesions are observed in many pediatric patients with tuberous sclerosis complex (TSC). Single studies indicate that hyperfiltration is common in this group of patients. Our study aimed to evaluate renal function and frequency of hyperfiltration in children with TSC based on creatinine and cystatin C levels.

Material and methods:

 In 44 children with TSC (age 2 years, mean age 8.26±5.52 years), we evaluated estimated GFR using simplified creatinine-based Schwartz formula (eGFRCr) and creatinine-, urea-, and cystatin C-based Schwartz formula (eGFRCrUrCys) [mL/min/1.73m2]. Hyperfiltration was defined as eGFR >140 mL/min/1.73m2. In all patients, we also analyzed clinical and biochemical data and renal lesions by measuring the largest lesion diameter (angiomyolipoma – AML and cysts).

Results:

 34 (77.3%) patients had renal AMLs, including 6 with large AMLs (>30 mm) and 36 (81.8%) had renal cysts. eGFRCr was from 96 to 230, mean 140.1±31.8, eGFRCrUrCys was from 82 to 153, mean 111.0±15.6 mL/min/1.73m2. The difference between eGFRCr and eGFRCrUrCys was from 0.18 to 88.8, mean 30.0±20.8  mL/min/1.73m2. Hyperfiltration was found in 17 (38.6%) using eGFRCr and in 2 (4.5%) using eGFRCrUrCys. Serum cystatin C varied from 0.53 to 1.45, mean 0.84±0.20 [mg/L], and was normal in all but three (6.8%) children. There was no difference between patients with hyperfiltration (defined using eGFRCr) and patients with normal eGFRCr in age, sex, biochemical parameters, and renal lesions. eGFRCr  and the difference between eGFRCr and eGFRCrUrCys correlated with age (r=-0.387, p=0.009; r=-0.479, p<0.001) whereas there was no such correlation for eGFRCrUrCys.

Conclusions:

1. Children with TSC have normal kidney function, even with very large kidney lesions.

2. The simplified Schwartz formula does not accurately assess renal function in children with TSC and may lead to overdiagnosis of hyperfiltration, especially in the youngest patients.

3. Cystatin C -based evaluation of eGFR should be routinely used in pediatric TSC patients.