Rheumatology Advance Access originally published online on September 13, 2005
Rheumatology 2006 45(1):85-91; doi:10.1093/rheumatology/kei110
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The spectrum of renal tubular acidosis in paediatric Sjögren syndrome
Department of Pediatrics, Divisions of 1 Rheumatology and 2 Nephrology, The Children's Hospital of Philadelphia, 3 University of Pennsylvania School of Medicine, Philadelphia, PA, 4 Division of Rheumatology, Children's Hospital and Regional Medical Center, Seattle, WA, USA and 5 Division of Rheumatology, Department of Internal Medicine, The 2nd Affiliated Hospital, Sun Yat-sen University, Guangzhou 510120, People's Republic of China.
Correspondence to: F. Pessler, Department of Pediatrics, Division of Rheumatology, The Children's Hospital of Philadelphia, 3405 Civic Center Boulevard, Philadelphia, PA 19104, USA. E-mail: pessler{at}email.chop.edu
Objectives. Renal tubular acidosis (RTA) is a well-recognized extraglandular complication of adult Sjögren syndrome (SS) but has been reported only rarely in paediatric SS. We wished to describe the natural history of RTA in paediatric SS.
Methods. We performed a chart and literature review. Inclusion criteria were primary or secondary SS with onset before 18 yr of age, complicated by RTA before 18 yr of age.
Results. Twelve cases were identified: two from chart review and 10 from the literature. RTA was mostly associated with primary SS. RTA was detected at the onset of SS or up to 9 yr later. The clinical spectrum ranged from nearly silent to life-threatening, with plasma pH and serum potassium as low as 7.0 and 1.2 mEq/l, respectively. Hypokalaemia was present in 92%. Half the patients presented with profound weakness or paralysis, most likely from hypokalaemia. Proximal, distal and mixed RTA were detected, reflecting a diffuse ‘tubulopathy’ from interstitial nephritis, which was the predominant histopathological finding. Diabetes insipidus was the most frequent renal comorbidity. The RTA stabilized in 82% of the cases and resolved in one case. Only one patient had long-term unstable RTA.
Conclusions. RTA is an under-recognized complication of paediatric SS. It can be life-threatening in the acute phase but generally has a good long-term renal outcome. SS should be considered in the older child with otherwise unexplained RTA. Likewise, RTA should be excluded in children and adolescents with SS who develop weakness, fatigue or growth failure. Early recognition would reduce long-term complications such as growth failure.
KEY WORDS: Growth failure, Paediatric Sjögren syndrome, Renal tubular acidosis, Sjögren syndrome
These two authors contributed equally.