Department of Nephrology and Neonatology, Tokyo Metropolitan Children's Medical Center, 2-8-29 Musashidai, Fuchu, Tokyo, 183-8561, Japan.
Department of Nephrology, Tokyo Metropolitan Children's Medical Center, 2-8-29 Musashidai, Fuchu, Tokyo, 183-8561, Japan.
BMC Nephrol. 2021 Aug 30;22(1):295. doi: 10.1186/s12882-021-02497-6.
In typical cases of Bartter syndrome (BS), assessing response to diuretics (furosemide and thiazide), hereinafter referred to as diuretic loading test, may be used to diagnose the type by detecting which part of the kidney tubule is not functioning correctly. However, the diuretic loading test may not always agree with the results of genetic analyses.
A 5-year-old boy was admitted due to lower extremity weakness and abnormal gait. He had a recurrent episode of muscle weakness and laboratory results showed severe hypokalemia. The direct genomic sequencing of the case revealed a new mutation in the SLC12A1 gene, which is associated with type I Bartter syndrome. Because there was the difference between the phenotype and genotype, we conducted a diuretic loading test to confirm the diagnosis. However, the results showed a clear increase in urine excretion of Na and Cl. These results were not consistent with typical type I BS, but consistent with the patient's phenotype.
The diuretic loading test has limited utility for diagnosis especially in atypical cases. On the other hand, this test, which allows assessment of channel function, is useful for better understanding of the genotype-phenotype correlation.
在典型的巴特综合征（BS）病例中，评估利尿剂（呋塞米和噻嗪类）的反应，以下简称利尿剂负荷试验，可用于通过检测肾脏肾小管的哪一部分不能正常工作来诊断类型。然而，利尿剂负荷试验并不总是与基因分析的结果一致。
一名 5 岁男孩因下肢无力和步态异常入院。他曾多次出现肌肉无力，实验室检查结果显示严重低钾血症。该病例的直接基因组测序显示 SLC12A1 基因的一个新突变，与 I 型巴特综合征有关。由于表型和基因型之间存在差异，我们进行了利尿剂负荷试验以确认诊断。然而，结果显示尿液中 Na 和 Cl 的排泄明显增加。这些结果与典型的 I 型 BS 不一致，但与患者的表型一致。
利尿剂负荷试验对诊断的应用有限，特别是在非典型病例中。另一方面，这种测试可以评估通道功能，有助于更好地了解基因型-表型相关性。
