We describe an unusual case of systemic lupus erythematosus with pulmonary manifestations presenting as hypoglycemia due to anti-insulin receptor antibodies. A 38-year-old female suffered an episode of unconsciousness and was admitted to hospital where her blood glucose was found to be 18 mg/dL. During the hypoglycemic episode, her serum insulin level was inappropriately high (2,207.1 pmol/L; normal range, 18 to 173) and C-peptide level was elevated (1.7 nmol/L; normal range, 0.37 to 1.47). Further blood tests revealed the presence of antinuclear antibodies, anti-double-stranded DNA antibodies, and anti-Ro/SSA, anti-La/SSB, anti-ribonucleoprotein, and anti-insulin receptor antibodies. A computed tomography scan of the abdomen, aimed at tumor localization, such as an insulinoma, instead revealed ground-glass opacities in both lower lungs, and no abnormal finding in the abdomen. For a definitive diagnosis of the lung lesion, video-associated thoracoscopic surgery was performed and histopathological findings showed a pattern of fibrotic non-specific interstitial pneumonia.
Adult ; Autoantibodies/*blood ; *Autoimmunity ; Biological Markers/blood ; Blood Glucose/metabolism ; Female ; Humans ; Hypoglycemia/blood/*complications/immunology ; Insulin/blood ; *Insulin Resistance ; Lung Diseases, Interstitial/diagnosis/*etiology/immunology/surgery ; Lupus Erythematosus, Systemic/*complications/diagnosis/immunology ; Receptor, Insulin/*immunology ; Thoracic Surgery, Video-Assisted ; Tomography, X-Ray Computed ; Treatment Outcome