Hypokalaemic periodic paralysis can be primitive or secondary to potassium deficiency which can arise from several causes. Primary Sjogren's syndrome is a rare cause related to kidney involvement.
A 50-year-old woman has been admitted for hypotonic tetraparesis which had appeared a few days earlier. History taking revealed three previous similar episodes with a notion of oral and lacrimal dryness. Laboratory tests revealed severe hypokalaemia, hyperchloremia, alkaline urinary pH and a minima 24h proteinuria. Additional investigations led to the diagnosis of a primary Sjogren's syndrome defined on the basis of international criteria. Kidney biopsy revealed tubular-interstitial nephritis. Oral corticosteroïd therapy and potassium supplementation led to symptom improvement. A recurrent episode also responded to treatment. Additional urinary alkalinisation has prevented further relapse.
Primary Sjogren's syndrome is an exocrine disease causing systemic disorders. Tubular-interstitial nephropathy may occur in 25 percent of patients leading to distal tubular acidosis defined by the association of hypokalaemia, hyperchloremia and alkaline urinary pH. When hypokalaemia is severe, periodic paralysis may occur.
Primary Sjogren's syndrome can lead to nephropathy and subsequent hypokalaemic periodic paralysis. Urinary alkalinisation is essential to prevent this catastrophic presentation from recurring.