Selective Bilateral and Simultaneous Catheterization of the Inferior Petrosal Sinus: CRF Stimulates Prolactin Secretion From Acth‐producing Microadenomas in Cushing's Disease

Abstract

Bilateral, selective and simultaneous catheterization of the inferior petrosal sinus with measurements of ACTH after stimulation with ovine corticotrophin-releasing factor (CRF) is now frequently used to establish the differential diagnosis in patients with Cushing's disease and to determine the side of the microadenoma in the pituitary. To investigate whether CRF has any effect on other pituitary hormones, we also determined prolactin (PRL) concentrations in the samples obtained during this procedure. Fourteen patients under evaluation for Cushing's syndrome and one patient with a hormonally inactive pituitary tumour were catheterized. Baseline PRL levels in the peripheral veins were within the normal range before and after CRF in all patients (3.7-16.0 ng/ml). In 10 patients ACTH- and PRL concentrations lateralized to one side of the pituitary and could both be stimulated by CRF. The gradient of PRL between inferior petrosal sinus and periphery ranged from 7 to 147 ng/ml after CRF. There was no correlation between ACTH and prolactin increase in response to CRF. In three patients with no ACTH-gradient but a positive response to CRF, no tumours could be found during transsphenoidal surgery; they had no PRL-gradient and showed no PRL response to CRF. One patient with the ectopic ACTH syndrome had no ACTH- and no PRL response to CRF. The patient with the inactive pituitary tumour showed a normal ACTH-, but no PRL response to CRF. These data demonstrate for the first time that in normo-prolactinaemic patients with Cushing's disease, in contrast to patients bearing no microadenoma, PRL is secreted in response to CRF.(ABSTRACT TRUNCATED AT 250 WORDS)

Inferior petrosal sinus ACTH and prolactin responses to CRH in ACTH-dependent Cushing’s syndrome: a single centre experience from the United Kingdom

“…Our findings also add to the existing literature on the presence of inferior petrosal sinus gradients for prolactin in patients who harbour a pituitary corticotroph adenoma. It has long been recognised that in addition to ACTH, intersinus gradients for prolactin, growth hormone, thyrotrophin-secreting hormone, alpha-human chorionic gonadotrophin and beta-endorphin [14][15][16][17][18] can be detected in blood samples from inferior petrosal sinuses of patients with surgically and histologically confirmed Cushing's disease in the basal unstimulated state. Moreover, stimulation with CRH has been shown to induce further increases in the concentrations of prolactin, growth hormone, thyroid-stimulating hormone, alpha-subunit, tumour necrosis factor-alpha, alpha-melanocyte stimulating hormone and arginine vasopressin [14,[19][20][21][22][23][24][25][26] in blood from the dominant inferior petrosal sinus (the petrosal sinus with the maximal ACTH response), although these paradoxical responses of other hormones are not consistently seen [27].…”

The diagnosis and differential diagnosis of Cushing's syndrome

“…A significant gradient was found in only 26% of cases where the internal jugulars were sampled but this rose to 46% when samples were obtained from the inferior petrosal sinus, and to 85% following the administration of CRH. The measurement of other peptides in addition to ACTH has been reported as increasing the efficacy of inferior petrosal sinus sampling, particularly prolactin (Schulte et al, 1988;Crook et al, 1988). Vasopressin secretion has been shown to lateralize to the side of ACTHsecreting tumours, which is of interest in understanding the aetiology of Cushing's disease (Wittert er al., 1990).…”

Occult eutopic Cushing's syndrome--failure of simultaneous bilateral petrosal sinus sampling to diagnose pituitary-dependent Cushing's syndrome

“…To our knowledge, four other cases have been reported resembling the one reported by us (14)(15)(16). In each case, IPS sampling was performed by experienced clinicians.…”