Clinical medicine (London, England)
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A 58-year-old Chinese woman with well controlled type 1 diabetes mellitus presented with acute and progressive bilateral lower limb weakness. Investigations revealed severe hypokalaemia (1.3 mmol/L) and hypophosphataemia (<0.32 mmol/L) with rhabdomyolysis and electrocardiogram changes, without other concurrent biochemical abnormalities. Immediate intravenous and oral potassium and phosphate replacement was initiated with objective improvement in weakness with replenished electrolyte levels. ⋯ A computerised tomography scan showed atrophy of her salivary glands and a skin lesion biopsied by her GP in the past had been histologically characterised as anetoderma. The constellation of these findings and subsequent positive anti-SSA/SSB levels confirmed her diagnosis of primary Sjögren's syndrome (PSS). PSS has a wide spectrum of renal involvement and should be a differential diagnosis when investigating interstitial nephritis and electrolyte abnormalities, particularly in patients with coexisting autoimmune conditions.