Case Report: Gitelman syndrome with a suspected MEFV- associated autoinflammatory phenotype: diagnostic challenges in a complex case.

We report a rare case of genetically confirmed Gitelman syndrome (GS) in a Chinese female patient presenting with systemic inflammatory manifestations and a heterozygous MEFV variant of uncertain significance. The patient initially exhibited arthritis, elevated inflammatory markers, and a positive labial gland biopsy, raising suspicion for Sjögren's syndrome. However, absence of sicca symptoms and failure to meet the 2016 ACR/EULAR classification criteria excluded a definitive diagnosis. Persistent hypokalemia, hypomagnesemia, and metabolic alkalosis led to genetic testing, which identified compound heterozygous pathogenic variants in SLC12A3, confirming GS. Although the MEFV variant suggested a possible autoinflammatory phenotype, established diagnostic criteria for familial Mediterranean fever were not fulfilled. This case highlights the diagnostic complexity arising from overlapping renal and inflammatory features and underscores the importance of cautious genetic interpretation and multidisciplinary evaluation in complex multisystem presentations.