Insulin receptor autoantibody-mediated hypoglycemia in a woman with mixed connective tissue disease

Autoantibodies to the insulin receptor are rare and typically cause severe insulin resistance and hyperglycemia, a condition termed type B insulin resistance. Uncommonly, antibodies to the insulin receptor can cause hypoglycemia. We present the case of a woman who developed recurrent severe hypoglycemia and myopathy, was found to have insulin receptor autoantibodies and mixed connective tissue disease, and had resolution of hypoglycemia with immunosuppression. A 55-year-old woman with a history of obesity, hypertension, and prior hemorrhagic stroke presented with recurrent severe hypoglycemia. A diagnostic fast resulted in hypoinsulinemic hypoketotic hypoglycemia. Adrenal function was intact. Progressive myopathy had developed simultaneously with her hypoglycemia, and rheumatologic evaluation revealed mixed connective tissue disease. The plasma acylcarnitine profile was normal, extensive oncologic evaluation including IGF-2 measurement was unrevealing, and anti-insulin antibody testing was negative. Ultimately, anti-insulin receptor antibodies were found to be present. The patient was treated with glucocorticoids and rituximab. Eight weeks after initiation of immunosuppression, the insulin receptor antibody titer had decreased and hypoglycemia had resolved. Eight months after diagnosis, the patient remained free of severe hypoglycemia despite tapering of glucocorticoids to a near-physiologic dose. Though antibodies to the insulin receptor typically cause severe insulin resistance, this patient had no evidence of insulin resistance and instead presented with recurrent severe hypoglycemia, which responded to glucocorticoids and rituximab. The diagnosis of insulin receptor antibody-mediated hypoglycemia is rare but should be considered in patients with systemic autoimmune disease, including mixed connective tissue disease, in the appropriate clinical context.

A Rare Case of Fatal Hemorrhagic Stroke in a Young Female with Early Mixed Connective Tissue Disease

Mixed connective tissue disease (MCTD) often presents as a slow progressive illness with low morbidity and mortality. Serious central nervous system disease is uncommon, and fatal outcomes are rarely seen. Here, we report a rare case of fatal hemorrhagic stroke in a 43-year-old female with a rapidly progressive MCTD. She presented to primary care with a history of headaches, visual disturbances, and unprovoked lower extremity swelling and pain. A rheumatological workup showed positive antinuclear (ANA) and ribonucleoprotein (RNP) antibodies. Magnetic resonance imaging (MRI) found a 12 mm hemorrhage along a cortical sulcus of the right frontal lobe, and a follow-up magnetic resonance angiography (MRA) and ophthalmological exam showed no definitive signs of vasculitis. Over the course of her workup, she developed swollen hands, Raynaud’s syndrome, myalgias, and synovitis characteristic of evolving MCTD. The patient then began to experience severe headaches over one month. Repeat MRI was ordered, but never completed, and the patient presented to the emergency department (ED) with a severe, right-sided headache, and left-sided visual disturbance. In the ED, she began to display evidence of delirium and seizure activity and became unresponsive. A computerized tomography scan (CT) of the brain showed a right parietal lobe intraparenchymal hemorrhage approximately 5 × 3 × 5 cm in size with secondary mass effect including mid- and hind-brain herniation. Computerized tomography angiography (CTA) of the brain showed signs of large vessel vasculitis. A craniectomy was performed; however, the patient never regained consciousness and died several days later. Vasculitis, while rare in connective tissue diseases, should be aggressively assessed for and managed in patients with any early signs and symptoms of cerebrovascular involvement to prevent fatal outcomes.

Elevated IgG Antibody to Aluminum Bound to Human Serum Albumin in Patients with Crohn’s, Celiac and Alzheimer’s Disease

Aluminum is in our water and food, and is used as an adjuvant in vaccines. About 40% of the ingested dose accumulates within the intestinal mucosa, making the gut the main target of inflammation and autoimmunity; about 1% accumulates in the skeletal system and brain, inducing the cross-linking of amyloid-β-42 peptide and the formation of amyloid aggregates associated with Alzheimer’s disease. To examine whether the accumulation of aluminum in the gut and brain tissues results in neoantigen formation, we bound aluminum compounds to human serum albumin. We used ELISA to measure IgG antibody in 94 different sera from healthy controls and 47 sera from each group of patients: anti-Saccharomyces cerevisiae antibody-positive (Crohn’s), and positive for deamidated α-gliadin and transglutaminase-2 IgA antibodies (celiac disease), autoimmune disorders associated with intestinal tissue antigens. Because earlier studies have shown that aluminum exposure is linked to Alzheimer’s disease etiology, and high aluminum content is detected in Alzheimer’s patients’ brain tissue, we also measured aluminum antibody in the blood of these patients. Additionally, we measured aluminum antibody in the sera of mixed connective tissue disease patients who were positive for antinuclear antibodies, and used them as disease controls. We found significant IgG antibody elevation against all three aluminum compounds in the sera of patients with Crohn’s, celiac and Alzheimer’s disease, but not in patients with mixed connective tissue disease. We concluded that aluminum ingestion and absorption from the GI tract and brain may contribute to Crohn’s, celiac and Alzheimer’s disease, but not to mixed connective tissue disease.