Ghazale Amaar, Chari Suresh T, Smyrk Thomas C, Levy Michael J, Topazian Mark D, Takahashi Naoki, Clain Jonathan E, Pearson Randall K, Pelaez-Luna Mario, Petersen Bret T, Vege Santhi Swaroop, Farnell Michael B
Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
Am J Gastroenterol. 2007 Aug;102(8):1646-53. doi: 10.1111/j.1572-0241.2007.01264.x. Epub 2007 Jun 6.
To determine the sensitivity and specificity of elevated serum IgG4 level for the diagnosis of autoimmune pancreatitis (AIP) and its ability to distinguish AIP from pancreatic cancer, its main differential diagnosis.
We measured serum IgG4 levels (normal 8-140 mg/dL) in 510 patients including 45 with AIP, 135 with pancreatic cancer, 62 with no pancreatic disease, and 268 with other pancreatic diseases.
Sensitivity, specificity, and positive predictive values for elevated serum IgG4 (>140 mg/dL) for diagnosis of AIP were 76%, 93%, and 36%, respectively, and 53%, 99%, and 75%, respectively, for IgG4 of >280 mg/dL. Among subjects with elevated IgG4, non-AIP subjects (N = 32) differed from AIP subjects (N = 34) in that they were more likely to be female (45%vs 9%, P < 0.001), less likely to have serum IgG4 >280 mg/dL (13%vs 71%, P < 0.001), or elevation of total IgG (16%vs 56%, P < 0.001). Serum IgG4 levels were elevated in 13/135 (10%) pancreatic cancer patients; however, only 1% had IgG4 levels >280 mg/dL compared with 53% of AIP. Compared with AIP, pancreatic cancer patients were more likely to have CA19-9 levels of >100 U/mL (71%vs 9%, P < 0.001).
Elevated serum IgG4 levels are characteristic of AIP. However, mild (<2-fold) elevations in serum IgG4 are seen in up to 10% of subjects without AIP including pancreatic cancer and cannot be used alone to distinguish AIP from pancreatic cancer. Because AIP is uncommon, IgG4 elevations in patients with low pretest probability of having AIP are likely to represent false positives.
确定血清IgG4水平升高对自身免疫性胰腺炎（AIP）诊断的敏感性和特异性，以及其区分AIP与主要鉴别诊断疾病胰腺癌的能力。
我们检测了510例患者的血清IgG4水平（正常范围8 - 140mg/dL），其中包括45例AIP患者、135例胰腺癌患者、62例无胰腺疾病患者以及268例其他胰腺疾病患者。
血清IgG4水平升高（>140mg/dL）对AIP诊断的敏感性、特异性和阳性预测值分别为76%、93%和36%，而IgG4水平>280mg/dL时分别为53%、99%和75%。在IgG4水平升高的受试者中，非AIP受试者（N = 32）与AIP受试者（N = 34）的不同之处在于，非AIP受试者更可能为女性（45%对9%，P < 0.001），血清IgG4>280mg/dL的可能性更低（13%对71%，P < 0.001），或总IgG升高的可能性更低（16%对56%，P < 0.001）。13/135（10%）的胰腺癌患者血清IgG4水平升高；然而，只有1%的患者IgG4水平>280mg/dL，而AIP患者中这一比例为53%。与AIP相比，胰腺癌患者CA19 - 9水平>100U/mL的可能性更高（71%对9%，P < 0.001）。
血清IgG4水平升高是AIP的特征。然而，高达10%无AIP的受试者（包括胰腺癌患者）血清IgG4有轻度（<2倍）升高，因此不能单独用其区分AIP与胰腺癌。由于AIP不常见，AIP患病前概率低的患者中IgG4升高可能为假阳性。
