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JAMA Diagnostic Test Interpretation
January 15, 2019

Immunoglobulin G4 Levels

Author Affiliations
  • 1College of Medicine, Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota
JAMA. 2019;321(2):202-203. doi:10.1001/jama.2018.16665

A 67-year-old man with type 2 diabetes mellitus and hyperlipidemia was evaluated for unintentional weight loss of 28 lb (12.7 kg) and increasing fasting blood glucose values over the past 6 months. A computed tomography scan showed diffuse enlargement of the pancreas with peripheral hypoenhancement but no discrete mass. Soft tissue surrounded the infrarenal abdominal aorta, extended along the common iliac arteries, and obstructed the left ureter, causing hydronephrosis. He was referred for evaluation of possible malignancy. Laboratory studies including immunoglobulin G subgroup 4 (IgG4) levels are shown in the Table. Fine-needle aspiration of the pancreas showed no malignancy. Colonoscopy results 8 months ago were normal.