HIGH-YIELD PEARL 3 A 28-year-old woman suddenly develops quadriparesis. Her serum potassium is 1.9 mEq/L. Creatinine is normal. Could this be the FIRST manifestation of an autoimmune disease? YES. Think SJÖGREN’S DISEASE. A clinical trap every rheumatologist and physician must recognise. 5 CLUES YOU MUST NOT MISS 1. Severe hypokalaemia can cause paralysis Acute flaccid weakness, occasionally progressing to respiratory muscle involvement. ECG abnormalities and life-threatening arrhythmias may occur. Don’t automatically label it familial hypokalaemic periodic paralysis. 2. The acid–base status provides the biggest clue Hypokalaemia + normal anion gap metabolic acidosis = THINK RENAL TUBULAR ACIDOSIS (RTA). 3. Check the urine pH In classical distal (Type 1) RTA: The kidney fails to acidify urine appropriately. Urine pH typically remains >5.5 despite systemic metabolic acidosis. Renal potassium wasting may be present. 4. Normal creatinine DOES NOT exclude renal involvement Sjögren’s disease commonly produces tubulointerstitial pathology rather than glomerular disease. Look for: Distal RTA Nephrolithiasis or nephrocalcinosis Hypocitraturia Tubular concentrating defects 5. Sicca symptoms may be absent or unrecognised Renal manifestations can precede the diagnosis of Sjögren’s disease. Consider anti-SSA/Ro testing and an appropriate Sjögren evaluation when the clinical context supports it. QUESTION What is the mechanism of distal RTA in Sjögren’s disease? ANSWER: Immune-mediated tubulointerstitial injury impairs distal urinary acidification, involving dysfunction of the collecting duct’s acid-secreting machinery, including H⁺-ATPase. This produces impaired hydrogen ion secretion, metabolic acidosis and often renal potassium wasting. THE LIFE-SAVING TREATMENT PEARL In severe symptomatic hypokalaemia: Urgent potassium replacement with cardiac monitoring. Correct associated magnesium deficiency, if present. Introduce alkali therapy after appropriate potassium correction, with close electrolyte monitoring. Potassium citrate is useful for longer-term management in suitable patients. REMEMBER: A normal creatinine does not mean normal renal tubular function. And sudden paralysis may be the first clue to Sjögren’s disease. #Rheumatology #SjogrensDisease @IhabFathiSulima