Distal renal tubular acidosis(RTA) is well-recognized complication of immunologically mediated condition such as Sjoogren's syndrome, SLE, idiopathic hypergammaglobulinemia, autoimmune liver disease, autoimmune thyroid disease, multiple myeloma,
and
renal tranplant rejection.
Tubulointerstitial involvement frequently occurrs in SLE. A spectrum of abnormalities includng impaired urinary concentration of acidification, increased fractional excretion of low molecular weight protein, hyporeninaemic hypoaldosteroniam and
impaired
tubular potassium excretion can occur in SLE. But complete distal RTA associated with SLE is rare. We report a 13 year-old female with SLE and distal RTA which was diagnosed by NaHCO3 loading test. She had nephrotic syndrome, hypokalemia,
hyperchloremic
metabolic acidosis with alkali urine. She had fatiquebility, general weakness, intermittent fever and chest pain for at least 12months. And then, the butterfly-shaped malar rash was developed, so pediatrician suspected SLE suspected SLE and she
was
refer to us. At hospitalization, She had malar rash, pericardial effusion, persistent proteinuria greater than 3+, hemolytic anemia, lymphopenia, leukopenia, positive LE cell, Anti-DNA Ab and posotive ANA. So her clinical data are satisfied ARA
criteria
for SLE. Her renal biopsy showed diffuse proliferative SLE nephpritis and marked focal tubular atrophy with localized heavy mononuclear cell infiltration and fibrosis. We performed NaHCO3 loading test to confirm distal RTA. During the test, we
detected
the inability to achieve a high urinary PCO2.
This result is the most sensitive index of impaired distal acidification, so we can diagnose distal RTA. She had a good response to the therapy with prednisolone, NaHCO3 and oral KCL supplement.
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