Inferior petrosal sinus sampling in acromegaly.

In view of the diagnostic value of bilateral simultaneous inferior petrosal sinus sampling (BSIPSS) in localising preoperatively the site of the microadenoma in pituitary dependent Cushing's disease, the clinical value of BSIPSS was evaluated in five acromegalic patients with equivocal or negative pituitary CT scans. Intersinus GH gradients were obtained for all patients (range 1.6-4.2) but in only one case was the gradient correctly localised to the side of the tumour. Gradients of several other pituitary hormones, particularly prolactin (range 1.6-4.0), also demonstrated gradients parallel to the GH intersinus gradients. Despite the paradoxical intersinus GH gradients, the surgeon was able to readily identify the tumour at the time of surgery. Thus BSIPSS is of little assistance to the surgeon for the preoperative radiological evaluation in acromegaly and these results caution against the universal adoption of the BSIPSS technique in the radiological assessment of all secretory pituitary microadenomas.

Multiple pituitary hormone gradients from inferior petrosal sinus sampling in Cushing's disease.

Pre-operative bilateral simultaneous inferior petrosal sinus sampling with assessment of ACTH levels in the left and right sinuses and the periphery was performed in 9 patients with pituitary dependent Cushing's disease who were subsequently found at surgery to have basophil microadenomata. The novel observation of this study was the pattern of secretion of other pituitary hormones so that significant inter-sinus gradients greater than or equal to 1.4:1 were seen for beta-endorphin (2.8 +/- 1.3, mean +/- SEM), PRL (4.2 +/- 1.3) and GH (6.9 +/- 2.4) as well as for ACTH (5.1 +/- 1.1). There was no inter-sinus gradient for LH, FSH and TSH. In these 9 patients with adenomata, the correlations between the inter-sinus gradients for ACTH and beta-endorphin were r = 0.95 (P less than 0.01), ACTH and PRL r = 0.90 (P less than 0.01) and for ACTH and GH r = 0.89 (P less than 0.05). This close association between the gradients for ACTH and other anterior pituitary hormones could be due either to co-secretion of beta-endorphin, PRL and GH by the ACTH-producing pituitary adenomata or to a paracrine effect of beta-endorphin from the tumours on adjacent pituitary tissue. By reflecting the central pituitary hormone milieu, petrosal sinus sampling can give information about pituitary function unobtainable from peripheral hormone levels.