Hypokalaemic Paralysis Revealing Sjogren's Syndrome in a 16-Year Old Girl

A 16-year old girl presented with rapid onset of muscular weakness and a history of severe dysphagia, dysphonia and significant wasting. On examination, she was dystrophic (BMI 15.7) and had signs of myopathy. Laboratory findings confirmed myopathy (CPK 106.4 microkat/L (6384 IU/L), AST 2.86 microkat/L (171.6 IU/L), myoglobin 1582 microg/L). There was profound hypokalaemia (S-K 1.8 mmol/L) suggesting hypokalaemic paralysis. Diagnosis of distal renal tubular acidosis (dRTA) was based on combination of hyperchloremic metabolic acidosis, severe hypokalaemia, high urinary pH and positive value of urinary anion gap. There was evidence of other signs of renal tubular impairment (urinary beta-2-microglobulin 213 mg/L, glomerulotubular proteinuria 1.01g/24h). Autoimmune tests (rheumatoid factor, antinuclear antibodies, autoantibodies to Ro/SSA and La/SSB) together with symptoms of xerostomia with swallowing difficulties and atrophic glossitis suggested primary Sjogren's syndrome (SS) as the underlying cause of dRTA. The renal biopsy confirmed chronic tubulo-interstitial nephritis compatible with this diagnosis. Full recovery of muscle weakness and hypokalaemia and acidosis followed after potassium and alkali replacement therapy. Corticosteroids were administered with subsequent addition of cyclosporine A because of disease activity. In conclusion, primary SS is a rare diagnosis in childhood and adolescence and should be considered in patients presenting with hypokalaemic paralysis, as this might be due to dRTA, even in the absence of apparent sicca syndrome.