Abstract
Traditional clinical diagnostic criteria for Gitelman syndrome (GS) including hypomagnesemia and hypocalciuria have been challenged by reports of atypical manifestations recently, as well as the development of genetic testing. Hydrochlorothiazide (HCT) test is a diagnostic method different from the traditional biochemical parameters, which could evaluate the function of thiazide-sensitive sodium-chloride co-transporter (NCC) in vivo by a small dose of NCC inhibitor HCT. In this retrospective study, we compared the diagnostic significance of hypomagnesemia, hypocalciuria, and the reaction of HCT test, among Chinese patients with GS confirmed by genetic test. For patients who were clinically suspected of GS manifestations, SLC12A3 gene was sequenced to make genetic diagnosis. A total of 83 GS and 19 control patients were recruited, among which 37 underwent HCT test according to the standard process. Compared with the gold standard of genetic diagnosis, both the diagnostic sensitivity (93.10%) and specificity (100.00%) of the HCT test were much higher than those of hypomagnesemia and/or hypocalciuria. The area under the receiver operating characteristic (ROC) curve was 1.000 (95% CI 0.905–1.000) for HCT test, higher than the values using hypomagnesemia and/or hypocalciuria. The cost of HCT test was around $54, much lower than genetic diagnosis. In conclusion, besides traditional hypomagnesemia and hypocalciuria, HCT test could be a valuable tool in the clinical diagnosis of Chinese GS patients.
Highlights
Gitelman syndrome (GS) (OMIM 263800) is a recessively inherited salt-losing renal tubulopathy
Clinical and biochemical data of the 83 GS and 19 non-GS patients were presented in Tables 1, 2
The average age of GS patients was (31.1 ± 13.0) years and 57.8% were men. Both GS patients and non-GS patients had a wide range of clinical manifestations associated with hypokalemia
Summary
Gitelman syndrome (GS) (OMIM 263800) is a recessively inherited salt-losing renal tubulopathy. It is caused by loss-of-function mutations in SLC12A3 which encodes the thiazide-sensitive sodium-chloride co-transporter (NCC) located in the apical membranes of the distal convoluted tubule (DCT) cells [1]. The disease is characterized by hypokalemic metabolic alkalosis, usually accompanied by hypomagnesemia and hypocalciuria [2]. Prior studies reported that GS patients showed a high phenotypic variability from mild weakness or nausea to life-threatening complications, such as ventricular arrhythmia. Most of them complained of poor quality of life [3]. It is challenging yet critical to establish a reliable method for diagnosing GS
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