A 43-year-old woman presented with a sudden onset of hypokalaemic paralysis requiring intubation and ventilatory support. Subsequent biochemical and clinical assessments established a diagnosis of distal renal tubular acidosis (RTA) in association with underlying Sjö gren's syndrome as the aetiology of her profound hypokalaemia. Distal RTA is rare, but Sjö gren's syndrome is one of the more common causes in adults and should be considered in the differential diagnosis of patients who present with hypokalaemic muscular paralysis. 2008; 45: 221-225. DOI: 10.1258 45: 221-225. DOI: 10. /acb.2007 Case report
Ann Clin BiochemA 43-year-old woman presented to hospital as an emergency with a 24 h history of rapidly progressive limb weakness associated with increasing breathlessness. Her husband had noticed mild weakness of her legs over the preceding week. She had no other systemic symptoms. There was no history of upper respiratory tract, bladder or bowel infection and no recent foreign travel.On examination, she was tachypnoeic and her speech was feeble. She had difficulty keeping her head upright due to profound neck weakness. Muscle power was reduced in all limbs to grade 2/5. She had a full range of eye movements. There was no sensory loss. The remainder of the clinical examination was unremarkable. She was intubated and ventilated in view of imminent respiratory arrest.Her past medical history included coeliac disease and hypothyroidism. She smoked 20 cigarettes per day and took alcohol only on an occasional basis. Her medications included thyroxine 150 mg daily, ranitidine 150 mg twice daily, venlafaxine 75 mg daily, tramadol hydrochloride 100 mg twice daily, and lactulose as required.Although Guillain-Barre syndrome was suspected as the initial diagnosis on clinical findings, biochemical findings were not supportive. These revealed a serum sodium of 139 mmol/L, potassium of 1.2 mmol/L, urea 6.6 mmol/L, creatinine 98 umol/L, bicarbonate 15 mmol/L, chloride 113 mmol/L, magnesium 0.95 mmol/L, calcium 2.08 mmol/L, albumin 31 g/L and phosphate 1.05 mmol/ L. Although a metabolic acidosis was present, the calculated anion gap was normal. Urinary pH was 6.73 with an arterial pH of 7.26. Initial urinary electrolyte measurements were potassium 15 mmol/L and sodium 46 mmol/L. Toxicology screen for paracetamol, tricyclic antidepressants, theophylline and salicylate was negative. Full blood picture showed a haemoglobin of 11.7 g/dL, white cell count 14.4 Â 10 9