Kidney manifestations of pediatric Sjögren's syndrome

Approximately 1% of all patients with Sjögren's syndrome (SS) are children. Unlike the adult form, in which sicca syndrome is the main presentation, in children, the most common clinical finding is recurrent enlargement of the salivary glands. In pediatric SS, extraglandular manifestations represent a significant feature and, among these, kidney manifestations are relevant. Kidney involvement is observed in 5-20.5% of children with SS, most frequently tubulointerstitial nephritis. This injury can lead to serious phenotypes, including distal kidney tubular acidosis with the development of severe hypokalemia, which can lead to ECG abnormalities, weakness, and hypokalemic periodic paralysis. Kidney implications in pediatric SS also include nephrolithiasis, nephrocalcinosis, and various types of glomerular damage, which often require immunosuppressive therapies. Laboratory findings are usually comparable to adults, including hyperglobulinemia and high rates of antinuclear antibodies (ANA, 63.6-96.2%), and anti-Ro/SSA (36.4-84.6%). The current classification criteria for SS are inaccurate for the pediatric population, and more specific criteria are needed to improve the diagnostic rate. Due to the rarity of the disease, strong recommendations for treatment are lacking, and several therapeutic strategies have been reported, mostly based on glucocorticoids and disease-modifying antirheumatic drugs, with different outcomes. The aim of this paper is to provide an overview of the kidney implications of pediatric SS based on the latest evidence of the medical literature.