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Abstract: PO1171

Distal Renal Tubular Acidosis in Patients with Autoimmune Diseases

Session Information

Category: Fluid, Electrolyte, and Acid-Base Disorders

  • 902 Fluid, Electrolyte, and Acid-Base Disorders: Clinical

Authors

  • Ion, Oana, Institutul Clinic Fundeni, Bucuresti, Romania
  • Ailincai, Ioana, Institutul Clinic Fundeni, Bucuresti, Romania
  • Fratila, Georgiana, Institutul Clinic Fundeni, Bucuresti, Romania
  • Ismail, Gener, Institutul Clinic Fundeni, Bucuresti, Romania
Background

Distal renal tubular acidosis (DRTA) is reported in association with autoimmune diseases. DRTA can evolve without symptoms and systemic acidosis, this form being defined as incomplete DRTA. The incomplete form necessitates the use of a urinary acidification test like the Furosemide and Fludrocortisone test for establishing the diagnosis.

Methods

We conducted a prospective observational study in a selected cohort of 48 patients diagnosed with autoimmune diseases (SLE, Sjögren syndrome, ANCA vasculitis, cryoglobulinemic vasculitis), who presented in our clinic from December, 2020 until May, 2021. The patients were submitted to Furosemide and Fludrocortisone test.

Results

The study included 48 patients (36 females, mean age 41.92 ± 15.7 years), diagnosed with SLE (33 patients), pANCA vasculitis (7 patients), cANCA vasculitis (1 patient), Sjögren syndrome (3 patients) and cryoglobulinemic vasculitis (4 patients). There was a significant difference regarding age (p<0.001) and eGFR (p<0.001) between the groups with vasculitis (mean age 60.7523roups with vasculitis ± 7.47 years, eGFR 41.66 ± 16.71 ml/min/1.73 m2), SLE (mean age 35.18 ± 11.74 years, eGFR 73.24 ± 25.18 ml/min/1.73 m2) and Sjögren syndrome (mean age 40.65 ± 20.03 years, eGFR 35.56 ± 17.24 ml/min/1.73 m2). The test was positive for 11 patients out of 48. There was not a significant change in kalemia during the test (p=0.860). There was a significant increase in the level of serum bicarbonate (26.23 ± 3.5 mmol/l before the test vs 28.21 ± .13 mmol/l after the test, p<0.001) and also in the level of serum pH (7.36 ± 0.44 before the test vs 7.38 ± 0.43 after the test, p=0.001). None of the patients reported digestive or allergic side effects. There was not a significant difference regarding eGFR (p=0.665), proteinuria (p=0.372) and CRP (p=0.246) between the patients with or without a positive test. Regarding immunological activity, patients with a positive test had a higher ANA value at the moment of the test (4.71 ± 3.04 U/ml vs 2.50 ± 2.55 U/ml, p=0.05) and a lower C4 value (12.66 ± 9.39 mg/dl vs 23.4 ± 11.54 mg/dl, p=0.016).

Conclusion

Incomplete DRTA was found in 11 out of 48 patients with autoimmune diseases. None of the patients developed severe hypokalemia or metabolic alkalosis or any other side effect after Furosemide and Fludrocortisone test.