Glomerular filtration rate in primary Sjögren's syndrome with renal disease

Renal disease in Primary Sjögren's syndrome (SS) is often overlooked, because of a paucity of symptoms. Distal renal tubular acidosis (dRTA) and tubulointerstitial nephritis (TIN) might be present. Only a few cases of SS with decreased glomerular filtration rate (GFR) have been reported. We have studied GFR in 27 female SS-patients, mean age 62 years (37-78). GFR was measured as the single injection 51Cr-EDTA plasma clearance. Eighteen women had normal GFR (group 1), and nine (33%) had values below the lower normal limit (group 2). In group 2, dRTA was present in 8/9 urolithiasis in 6/9, previous upper urinary tract infection (UTI) in 2/9 and TIN in 5/6 patients who were kidney biopsied. Among patients with dRTA 8/18 (44%) had decreased GFR. We conclude that decreased GFR is not unusual in SS-patients with dRTA, and decreased GFR is mostly associated with TIN. Urolithiasis and UTI may contribute to decreased GFR in some individuals.