IgG 4 -related hypophysitis leading to diabetes insipidus.

A 60-year-old man with chronic pancreatitis, type 2 diabetes, and alcohol dependence presented with two months of polyuria, polydipsia, two weeks of weight loss, and three days of fatigue. His blood pressure was 97/54 mmHg, temperature 39°C, and SpO2 94%. Chest exam showed bilateral basal crepitations, but the rest was normal. He was on metformin and insulin for diabetes. His blood tests were mostly normal, but his chest X-ray showed basal consolidations, leading to a pneumonia diagnosis treated with IV antibiotics. He developed metabolic acidosis and was transferred to the ICU. Low cortisol and ACTH levels pointed to adrenal insufficiency. MRI showed pituitary stalk enlargement, and IgG4 antibodies were elevated, confirming IgG4-related hypophysitis. He was started on steroids and desmopressin for adrenal insufficiency and diabetes insipidus, with improvements in his sodium levels and symptoms. IgG4-related disease, a rare condition, involves multiple organs, including the pituitary, causing hypophysitis and other systemic effects.