The Challenges of Managing Distal Renal Tubular Acidosis in Pregnant Patients with Primary Sjogren’s Syndrome

Summary: Authors: Elizabeth K. Chu MD1, Matilda L. Culp MD2, William M. Clapp MD3, Omar Tolaymat MD1 Author affiliations: 1. Department of Medicine, Division of Rheumatology and Clinical Immunology, University of Florida, Gainesville, Florida USA 2. Department of Medicine, University of Florida, Gainesville, Florida USA 3. Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, USA Background: Primary Sjogren’s Syndrome (pSS) is an autoimmune disorder characterized by lymphoplasmacytic infiltration of epithelial tissues, including the kidneys. Distal renal tubular acidosis (RTA) is the most common renal manifestation in pSS, resulting from impaired acid excretion in the distal nephron from serum into urine (1). Pregnancy exacerbates RTA due to physiological changes in renal function, potentially leading to adverse maternal and fetal outcomes (2–4). Case: We present a case of a pregnant woman diagnosed with pSS during pregnancy, who subsequently developed distal type I RTA. A G3P2 woman in her 40s presented with sicca symptoms. Her labs showed elevated creatinine (1.41 mg/dL up from a baseline of 1.03 mg/dL a year prior) at 12 weeks of gestation. Electrolyte studies showed hypokalemia, hyperchloremic normal anion gap metabolic acidosis, and urine pH 7.0, consistent with distal RTA. She had positive serologies including ANA 1:1280 speckled pattern, SSA 131 AU/ml by ELISA, and rheumatoid factor 88 IU/ML. Schirmer’s test was positive (<5 mm in 5 minutes in both eyes). Renal biopsy demonstrated chronic tubulointerstitial nephritis with 40% interstitial fibrosis (Figures 1 and 2). Treatment with prednisone 60 mg daily with taper led to initial improvement in renal function (creatinine <1) and symptoms. However, she developed mild worsening of renal function, recurrence of symptoms, and fetal uterine growth restriction, necessitating a temporary increase in steroid dose from prednisone 10 mg to 60 mg daily and initiation of azathioprine, which again led to improvement of renal function and sicca symptoms. Discussion: Distal RTA in pSS results from impaired acid secretion in the kidneys, hypothesized to be mediated by autoantibodies targeting H+-ATPase (5). Its prevalence varies widely, and pregnancy exacerbates RTA due to increased renal plasma flow and glomerular filtration rate(3) Timely recognition and management of RTA in pregnancy are crucial to prevent adverse maternal and fetal outcomes which can include impaired fetal growth, development, and distress often resulting in preterm labor (3). Renal biopsy is recommended to confirm the diagnosis and assess fibrosis extent, guiding treatment decisions. There are no standardized guidelines for managing RTA in pSS, but immunosuppressive agents such as glucocorticoids and steroid-sparing agents are commonly used (5). Our case highlights the challenge of managing RTA in pregnancy and the need for individualized treatment approaches. Conclusion: Pregnant patients with pSS could be at risk of developing RTA, which may adversely affect maternal and fetal health. Therefore, pregnant patients with pSS should be monitored early for development of RTA and interstitial nephritis. Timely treatment can improve maternal and fetal outcomes. However, further research is needed to establish optimal management strategies and outcomes for RTA in pregnant patients with pSS. References: 1. Evans R, Zdebik A, Ciurtin C, Walsh SB. Renal involvement in primary Sjögren’s syndrome. Vol. 54, Rheumatology (United Kingdom). Oxford University Press; 2015. p. 1541–8. 2. Yuvaraj A, Ghosh S, Shanmugasundaram L, Abraham G. Sjogren’s with distal renal tubular acidosis complicating pregnancy. J Obstet Gynaecol (Lahore). 2018 Apr 3;38(3):429–31. 3. Seong EY, Kim DW, Kim HJ, Rhee H, Song SH. Incomplete distal renal tubular acidosis uncovered during pregnancy: A case report. World J Clin Cases. 2023 Sep 6;11(25):5988–93. 4. Alkhasoneh M, Jacobs J, Kaur G. A case of severe metabolic acidosis during pregnancy. Clin Case Rep. 2019 Mar 1;7(3):550–2. 5. Ungureanu O, Ismail G. Distal Renal Tubular Acidosis in Patients with Autoimmune Diseases—An Update on Pathogenesis, Clinical Presentation and Therapeutic Strategies. Vol. 10, Biomedicines. MDPI; 2022.