P3.N266: Not just dry eyes and dry mouths: Sjögren's syndrome in a young adult presenting with severe hypokalemia and kidney stones

Introduction: Sjögren’s Syndrome (SS) is an autoimmune disorder characterized by the classic triad of keratoconjunctivitis sicca, xerostomia, and polyarthritis. Here, we present a unique case of a 21-year-old female initially presenting with severe weakness, hypokalemia, and nephrocalcinosis, ultimately diagnosed with Sjögren’s syndrome.

Case Description: A 21-year-old female with a history of kidney stones presented to the emergency department with severe weakness and muscle pain, making ambulation difficult over the past three days. The patient had been in her usual state of health until a month prior when she began experiencing progressive fatigue, muscle aches, joint pain, increased urination with thirst, periodic weakness, and paresthesia. Physical examination revealed bilateral upper and lower extremity weakness graded at 4/5. Laboratory findings (Table 1A) showed severe hypokalemia and non-anion gap metabolic acidosis. Kidney ultrasound revealed bilateral medullary nephrocalcinosis. The patient received a diagnosis of distal renal tubular acidosis (dRTA) resulting in hypokalemia, metabolic acidosis, and nephrocalcinosis. Electrolyte imbalances were aggressively corrected, leading to the resolution of weakness and myalgia. The patient was discharged with plans for Endocrinology follow-up due to subclinical hyperthyroidism with maximally suppressed TSH and Rheumatology follow-up for chronic fatigue, arthralgia, and suspected underlying autoimmune etiology for acquired dRTA.
During Rheumatology follow-up, the patient reported intermittent migratory arthralgia, severe fatigue, and increased urination with thirst. She denied morning joint stiffness, fever, rash, oral ulcers, dryness in her mouth or eyes, dental cavities, shortness of breath, abdominal pain, hematuria, or Raynaud’s symptoms. Subsequent outpatient lab workup is listed below (Table 1B).
Iodine-123 (I-123) radionuclide thyroid uptake scans revealed a diffusely enlarged thyroid gland with homogeneously increased uptake, consistent with Graves' disease. Due to a high suspicion for Sjögren’s syndrome, a salivary gland biopsy was performed, showing chronic inflammation with loose aggregates of lymphocytes and plasma cells in a periductal distribution and mild fibrosis, consistent with Sjögren's syndrome. The patient developed sicca symptoms two years after the initial presentation of dRTA, meeting the full diagnostic criteria for Sjögren's syndrome.

Discussion: Renal involvement can be the initial clinical manifestation of Sjogren’s syndrome, and our patient’s history of kidney stones may be its earliest presentation. Tubulointerstitial nephritis is the most common renal complication of SS, manifesting as sterile pyuria, chronic kidney disease, and various tubular defects, including dRTA and urinary concentrating defects with polyuria and polydipsia. dRTA typically presents with non-anion gap metabolic acidosis, nephrocalcinosis, and hypokalemia, leading to periodic paralysis, as observed in our patient. SS is frequently associated with positive antinuclear antibody, rheumatoid factor, and other autoimmune conditions such as Graves' disease.

Conclusion: While unusual, renal involvement such as kidney stones may be the first clinical manifestation of Sjögren’s syndrome. Med-Peds physicians should consider potential underlying Sjögren’s syndrome in young patients with a history of kidney stones.