Multiple pituitary hormone gradients from cavernous sinus sampling in patients with Cushing's disease

Cavernous sinus sampling in patients with adreno-corticotropic-hormone (ACTH) secreting pituitary adenomas has been used to identify directly ACTH hypersecretion from the pituitary and to predict the lateralization of a microadenoma. In our previous series, cavernous sinus sampling provided a sufficient central/peripheral (c/p) ratio of ACTH and the correct laterality of the pituitary lesion in all microadenomas situated in the lateral wing. To clarify the diagnostic value of other anterior pituitary hormones in relation to ACTH gradients, we evaluated multiple pituitary hormone gradients between a cavernous sinus and a peripheral vein and between both cavernous sinuses in patients with Cushing's disease.

Cavernous sinus sampling was done in 11 patients with clinical and biochemical features of ACTH-dependent Cushing's syndrome. In 9, pituitary adenoma was detected during trans-sphenoidal surgery and histologically confirmed, while 2 others were suspected of having ectopic lesions. Serum ACTH, prolactin (PRL), thyroid stimulating hormone (TSH), growth hormone (GH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) from catheters in both cavernous sinuses and from a peripheral vein were measured. The c/p ratios of each hormone and the intercavernous gradients were evaluated.

The c/p ratio of ACTH indicated the presense of pituitary lesions in all 9 patients with ACTH-secreting microadenomas. In addition, the intercavernous gradients of ACTH indicated the correct localization of microadenomas in all 6 patients with lateralized lesions. As for other hormones, the c/p ratios of GH, PRL, TSH and LH were significantly high in number 7, 6, 6 and 3 patients, respectively. In contrast, the significant step up of FSH was observed only in one patient. The intercavernous gradients of GH and PRL were significantly high in number 5 and 4 patients, respectively.

The intercavernous gradients of GH and PRL tend to indicate the lateralization of a microadenoma. The measurement of GH and PRL during cavernous sinus sampling may provide additional information, in the lateralization of ACTH-secreting microadenomas.