The clinical application of adjusted inferior petrosal sinus sampling in Cushing's disease

Objective Inferior petrosal sinus sampling(IPSS)is helpful in confirming the source of ACTH secreting tumor in ACTH-dependent Cushing's syndrome. However, false-negative results have been reported. Prolactin level adjustment may reduce false-negative results of IPSS. This study was to investigate the utility of prolactin measurement during IPSS in patients with Cushing's disease. Methods This study included 93 patients with a pathological diagnosis of Cushing's disease(n=87)or ectopic Cushing's syndrome(n=6). Clinical, biochemical, and radiological records were reviewed and all cases underwent IPSS with prolactin adjustment. Results Baseline and prolactin adjusted inferior petrosal sinus to peripheral gradient(IPS/P)ratio were significantly higher in patients with Cushing's disease than those with ectopic Cushing's syndrome[11.3(5.0-22.4)vs 1.4(1.2-2.0), 3.3(1.9-4.8)vs 0.5(0.2-1.0), both P<0.01]. False-negative rate of baseline IPSS was 10.3%. Prolactin level adjustment could improve the diagnostic accuracy rate of IPSS from 89.2 % to 96.8 % in Cushing's disease. Compared to other diagnostic procedures, the prolactin adjusted IPSS may achieve highest sensitivity and specificity. Conclusion Prolactin normalization may improve the accuracy of IPSS in predicting pituitary ACTH secreting adenoma and is helpful to adjust negative results of IPSS. (Chin J Endocrinol Metab, 2016, 32: 196-200) Key words: Cushing's disease; Inferior petrosal sinus sampling; Prolactin