Introduction: Multiple autoimmune syndrome (MAS) type 3 is characterized by the coexistence of autoimmune thyroid disease with other organ-specific or systemic autoimmune disorders, excluding adrenal insufficiency. MAS represents a form of polyautoimmunity, in which shared immunological mechanisms contribute to clustering of multiple autoimmune diseases within a single individual. Recent studies suggest the clinical spectrum of MAS continues to expand, with increasing recognition of diverse autoimmune combinations across different organ systems. However, detailed clinical characterization of MAS type 3 involving overlapping endocrine and neuromuscular autoimmune diseases in young adults remains limited. Cases: We report four young adults (aged 21–37 years) with heterogeneous manifestations of MAS type 3 involving endocrine and systemic autoimmune diseases. Autoimmune thyroid disease was identified in three patients, all diagnosed with Graves’ disease with suppressed thyroidstimulating hormone, elevated free thyroxine, and positive thyrotropin receptor antibodies. Autoimmune diabetes was present in three patients, including latent autoimmune diabetes in adults (LADA) and type 1 diabetes mellitus, with variable glycemic control (hemoglobin A1c range 6.7–13.9%) and C-peptide levels ranging from preserved to markedly reduced. Myasthenia gravis was observed in three patients. Additional autoimmune conditions included systemic lupus erythematosus, systemic sclerosis, rheumatoid arthritis, and ulcerative colitis. Notably, rare combinations such as Graves’ disease with LADA and myasthenia gravis, as well as coexistence with systemic autoimmune diseases, were identified. All patients received individualized multidisciplinary management. Clinical and biochemical improvement was observed in all cases, with stabilization of both endocrine and systemic autoimmune manifestations. Conclusion This case series highlights the heterogeneous and expanding clinical spectrum of MAS type 3, including rare combinations of autoimmune endocrine and systemic diseases in young adults. Early recognition of autoimmune clustering and comprehensive screening are essential to optimize management and improve outcomes. These findings provide insights into autoimmune disease clustering and support the need for proactive multidisciplinary management strategies.
Young Adult ; Humans ; Autoimmune Diseases

Introduction: Nonfunctioning pituitary adenomas (NFPA) may cause central hypothyroidism due to pituitary compression, often presenting with low thyroid-stimulating hormone (TSH). However, suppressed TSH in this setting should not automatically be attributed to pituitary dysfunction, as primary hyperthyroidism—such as Graves’ disease—may rarely coexist. Distinguishing between these disorders is essential to avoid misdiagnosis and inappropriate management. Case: A 42-year-old female presented with intermittent headache, visual field impairment, palpitations, fine tremors, and weight loss. Physical examination revealed visual field deficits and no goiter. Laboratory evaluation showed cortisol level of 1 µg/dL (normal: 3.7–19.4 µg/dL), luteinizing hormone 1.62 mU/L (normal: 2.4–12.6 mU/L), follicle-stimulating hormone 5.01 mU/L (normal: 3.5–12.5 mU/L), free thyroxine 4 28.32 pmol/L (normal: 12–22 pmol/L), TSH 0.02 µIU/mL (normal: 0.27–4.2 µIU/mL), and prolactin 70.84 ng/mL. Thyrotropin receptor antibody (TRAb) was 3.53 IU/L, confirming Graves’ disease. Contrast-enhanced brain magnetic resonance imaging demonstrated a pituitary macroadenoma (2.13 × 2.28 × 3.05 cm) with optic chiasm compression. The patient was diagnosed with NFPA, Graves’ disease, secondary adrenal insufficiency, possible hypogonadotropic hypogonadism, and hyperprolactinemia likely due to the stalk effect. Preoperative management included hydrocortisone replacement and antithyroid therapy. The patient subsequently underwent transsphenoidal surgery with appropriate perioperative care. Postoperatively, no new pituitary hormone deficiencies were observed. She was maintained on thiamazole 10 mg daily with clinical improvement and remains under regular follow-up. Conclusion This case highlights a rare but clinically important coexistence of NFPA and Graves’ disease. Suppressed TSH in patients with pituitary adenoma should not be assumed to reflect pituitary dysfunction without thorough evaluation. Comprehensive thyroid assessment is crucial to ensure accurate diagnosis and appropriate management.
Pituitary Neoplasms ; Graves Disease