Hypokalemic Periodic Paralysis Associated With Tubulointerstitial Nephritis in a Patient With Sjogren's Syndrome

Abstract

BACKGROUNDSjögren's syndrome (SS) is a systemic autoimmune disease characterized by chronic inflammation of the exocrine glands, mainly the salivary and lacrimal ones, causing keratoconjunctivitis sicca, xerostomia, xerotrachea and vaginal dryness. The population prevalence is 0.5-1% and it predominantly affects middle aged women in their fourth decade of life. Renal involvement can be found in up to 5% of patients with the primary form of the disease, occurring as interstitial nephritis or glomerulonephritis. CASE REPORTA 39-year-old female patient, with no previously known comorbidities. She reported two episodes of parotitis in 2006 and 2009 that were resolved with antibiotic treatment. In 2012, she was hospitalized with hypokalemic periodic paralysis. As of 2014, she started to follow up with the ophthalmology team due to xerophthalmia, at the time with a 2 mm Schirmer's test in the right eye and 3 mm in the left eye, with no defined etiology until then. In 2019, she underwent routine tests, which showed an increase in serum creatinine levels, hypokalemia and metabolic acidosis. Investigation of SS with distal tubular involvement was initiated. Salivary gland scintigraphy was performed, showing an important impairment in the accumulation and elimination of parotid and submandibular glands. Laboratory tests: potassium level of 3.3; creatinine level of 2.2; urine test showing hyposthenuria (urinary density of 1005) and urinary pH of 7; protein electrophoresis showing hypergammaglobulinemia; normal anion gap; chloride level of 107; positive rheumatoid factor; positive anti-Ro and anti-La; ANA: fine speckled nuclear pattern 1/640.