Summary

A 24-year-old female presented with generalised weakness, lethargy and aches in legs. She was subsequently found to be markedly hypokalaemic and have a metabolic acidosis. A diagnosis of distal renal tubular acidosis (RTA) was made. In addition to this failure to alkalinise her urine, she was unable to concentrate it and so a diagnosis of nephrogenic diabetes insipidus was reached. Further questioning revealed previous investigation of a connective tissue disorder thought to be primary Sjögren's syndrome. RTA is a recognised but rare complication of Sjögren's syndrome. Urinary alkalinisation using potassium bicarbonate was instituted; the patient responded well to treatment and is having outpatient follow-up.