Evaluation of the results of trans-sphenoidal surgery in acromegaly by assessment of the growth hormone response to thyrotrophin-releasing hormone

Post-operative surveillance for somatotroph, lactotroph and non-functional pituitary adenomas after curative resection: a systematic review

CONTEXT

Pituitary tumors are the third most common brain tumor and yet there is no standardization of the surveillance schedule and assessment modalities after transsphenoidal surgery.

EVIDENCE ACQUISITION

OVID, EMBASE and the Cochrane Library databases were systematically screened from database inception to March 5, 2020. Inclusion and exclusion criteria were designed to capture studies examining detection of pituitary adenoma recurrence in patients 18 years of age and older following surgical resection with curative intent.

EVIDENCE SYNTHESIS

A total of 7936 abstracts were screened, with 812 articles reviewed in full text and 77 meeting inclusion criteria for data extraction. A pooled analysis demonstrated recurrence rates at 1 year, 5 years and 10 years for non-functioning pituitary adenomas (NFPA; N = 3533 participants) were 1%, 17%, and 33%, for prolactin-secreting adenomas (PSPA; N = 1295) were 6%, 21%, and 28%, and for growth-hormone pituitary adenomas (GHPA; N = 1257) were 3%, 8% and 13%, respectively. Rates of recurrence prior to 1 year were 0% for NFPA, 1-2% for PSPA and 0% for GHPA. The mean time to disease recurrence for NFPA, PSPA and GHPA were 4.25, 2.52 and 4.18 years, respectively.

CONCLUSIONS

This comprehensive review of the literature quantified the recurrence rates for commonly observed pituitary adenomas after transsphenoidal surgical resection with curative intent. Our findings suggest that surveillance within 1 year may be of low yield. Further clinical trials and cohort studies investigating cost-effectiveness of surveillance schedules and impact on quality of life of patients under surveillance will provide further insight to optimize follow-up.

Investigation of responsiveness to thyrotropin-releasing hormone in growth hormone-producing pituitary adenomas

Objective. The aim of this study was to investigate how the paradoxical response of GH secretion to TRH changes according to tumor volumes. Methods. Patients with newly diagnosed acromegaly were classified as either TRH responders or nonresponders according to the results of a TRH stimulation test (TST), and their clinical characteristics were compared according to responsiveness to TRH and tumor volumes. Results. A total of 41 acromegalic patients who underwent the TST were included in this study. Between TRH responders and nonresponders, basal GH, IGF-I levels, peak GH levels, and tumor volume were not significantly different, but the between-group difference of GH levels remained near significant over the entire TST time. ΔGHmax-min during the TST were significantly different according to the responsiveness to TRH. Peak GH levels and ΔGHmax-min during the TST showed significantly positive correlations with tumor volume with higher levels in macroadenomas than in microadenomas. GH levels over the entire TST time also remained significantly higher in macroadenomas than in microadenomas. Conclusion. Our data demonstrated that the paradoxical response of GH secretion to TRH in GH-producing pituitary adenomas was not inversely correlated with tumor volumes.

Normal growth hormone secretion is rare after microsurgical normalization of growth hormone levels in acromegaly

The effect of microsurgery on growth hormone (GH) secretion was studied in 34 patients with acromegaly. All patients showed enlarged sella volumes according to encephalography and macroadenomas at surgery. Preoperative GH levels were elevated in all 34 patients and 14 had concomitant hyperprolactinemia. There was a correlation between basal GH levels and sella size. Visual field defects, suprasellar extension, long duration of the disease, hyperprolactinemia and aneuploidy were noted in patients with low as well as high levels of GH preoperatively. The average reduction of GH levels in the total series was 71 +/- 21% (mean +/- SD). A notably similar reduction of GH levels was seen regardless of preoperative GH levels, concomitant hyperprolactinemia, visual field defects, size of the adenoma, invasive growth or increasing experience of the surgeon. Therefore, normal GH levels after surgery were reached mainly in patients with moderate GH increments preoperatively. GH levels were normalized by surgery in 15 patients but only four of these showed normal GH response to TRH and iota-dopa tests. Thus, only four patients (12%) fulfilled these criteria for cure of GH homeostasis.

Postoperative persistent thyrotrophin releasing hormone-induced growth hormone release predicts recurrence in patients with acromegaly

OBJECTIVE

To assess the predictive value of postoperative thyrotrophin releasing hormone (TRH)-induced GH responsiveness in relation to (late) postoperative outcome in patients in remission after surgery for acromegaly.

PATIENTS

and methods One hundred and twenty-nine patients underwent surgery for acromegaly in our institution between 1977 and 1996. TRH tests and oral glucose tolerance tests (GTT) were performed and serum IGF-I concentrations were measured pre- and postoperatively and during follow-up. Criteria for postoperative remission were a mean serum GH concentration < 5 mU/l and/or serum GH after an oral glucose tolerance test < 1 mU/l immunofluorometric assay (IFMA) or < 2.5 mU/l (radioimmunosassay), together with a normal serum IGF-I concentration.

RESULTS

Preoperatively, the TRH-induced GH response was highly variable, with gradual overlap between 'nonresponders' and 'responders'. Arbitrarily defined as a doubling of serum GH concentration, 45.6% of patients were 'responders' to TRH. GH response after TRH injection was significantly correlated to the TRH-induced prolactin response but not to preoperative GH concentration or adenoma size. After surgery, remission was achieved in 83 of the 129 patients. Postoperative remission was significantly correlated to mean preoperative serum GH concentration and preoperative glucose-suppressed serum GH but not to tumour class. Seventy-one patients with early postoperative remission were followed without adjuvant treatment for a mean of 9.4 +/- 0.7 years (range 0-23 years). Forty-one of these patients were TRH responsive as defined by at least doubling of the serum GH concentration preoperatively. Of the 71 patients, 12 developed recurrence of disease, as defined by insufficient GH suppression during oral GTT, and elevated IGF-I and mean serum GH concentration. Irrespective of the preoperative response to TRH, the initial postoperative TRH test was predictive of developing disease recurrence with a sensitivity of 75% and a specificity of 100% when an absolute GH increase of 3.75 mU/l was chosen to define paradoxical responsiveness. A stimulated GH 1.6 times basal was predictive of recurrence with a sensitivity of 83% and a specificity of 73%, and 2.1 times basal was predictive with a sensitivity of 75% and a specificity of 80%. None of the 32 patients with postoperative normalization of the preoperatively present TRH-induced GH response, defined as a postoperative GH increase < 3.75 mU/l, developed recurrence of disease, while all nine patients with a GH increase above this level developed recurrence of acromegaly.

CONCLUSION

To our knowledge this is the first report which addresses the value of early postoperative TRH-induced GH responsiveness in predicting late surgical outcome using receiver-operating characteristic (ROC) curves to redefine a postoperative paradoxical response instead of arbitrarily chosen criteria. An absolute postoperative GH response of more than 3.75 mU/l was associated with recurrence in all nine patients, while all 32 patients with normalization of previously paradoxical response are still in remission. Our findings from this study demonstrate that the TRH test is a valuable tool in the early identification of patients at risk of developing postoperative recurrence of acromegaly.

Transsphenoidal surgery and adjuvant gamma knife treatment for growth hormone-secreting pituitary adenoma

OBJECT

The results of combined transsphenoidal surgery and adjuvant gamma knife surgery (GKS) for growth hormone (GH)-secreting adenoma were investigated using biochemical cure criteria for surgery and biological cure criteria for adjuvant GKS.

METHODS

Ninety patients (42 male and 48 female patients), ranging from 11 to 75 years of age, underwent transsphenoidal surgery for GH-secreting pituitary adenoma. Preoperative and postoperative GH and insulin-like growth factor-I levels were measured, as was the postoperative GH level after the oral glucose tolerance test. Tumor size, cavernous sinus (CS) invasion, and residual tumor were evaluated using magnetic resonance (MR) imaging. Transsphenoidal microsurgery was performed, followed by adjuvant GKS when there was persistent biochemical evidence of GH hypersecretion with residual tumor detectable in the CS on MR imaging. Patients in whom GKS was contraindicated were treated with conventional radiotherapy or by medical means.

CONCLUSIONS

The overall surgical cure rate was 57% based on recently accepted biochemical cure criteria. Patients with no CS invasion achieved a 100% cure rate, whereas patients with CS invasion achieved an 82% cure rate (14 of 17 patients) after adjuvant GKS. The combination of transsphenoidal microsurgery and adjuvant GKS is the optimal therapy for patients with GH-secreting adenoma.

Early postoperative growth hormone levels: high predictive value for long-term outcome after surgery for acromegaly

OBJECTIVES

To explore the prognostic value of early - within 1 week - postoperative growth hormone (GH) measurements with regard to outcome after surgery for acromegaly in a short- and a long-term perspective.

DESIGN

Retrospective study of patients operated on between 1987 and 1998, including follow-up for up to 60 months.

SETTING

University hospital.

SUBJECTS

Sixty-eight patients with acromegaly.

INTERVENTION

Pituitary surgery aiming at adenomectomy with preservation of pituitary function.

MAIN OUTCOME MEASURES

The effect of the operation was evaluated after 3 months, mostly by means of an oral glucose load or by insulin-like growth factor 1 (IGF-1). The specificity, sensitivity and the predictive values of an early postoperative mean GH concentration </= 4.8 mU L-1, as well as of the GH response to thyrotropin-releasing hormone (TRH) 3 months after surgery, were calculated with regard to outcome of the operation in both 3-month and long-term perspectives.

RESULTS

Fifty patients (73.5%) showed a satisfactory effect at the evaluation 3 months postoperatively; 45 of these were followed between 12 and 60 months. Relapse was registered in five cases: 12, 12, 24, 24 and 48 months after surgery. In the long-term perspective, the predictive value of an early mean GH </= 4.8 mU L-1 was 93.6% with regard to a satisfactory effect of surgery, compared with 90.2% for a normalized somatomedin C (SmC)/IGF-1 and 90.0% for an absent GH response after TRH. An early mean GH > 4.8 mU L-1 had a 77.8% predictive value for persistent or recurrent disease, compared with 85.7% for persistently increased SmC/IGF-1 and 68.8% for an abnormal GH release after TRH 3 months after surgery. In the short-term perspective, the specificity and the predictive value of an early GH </= 4.8 mU L-1 were 77.3 and 97.1%, respectively. Early GH > 4.8 mU L-1 had a 94.4% sensitivity but a predicative value of only 63.0% for an unsatisfactory effect.

CONCLUSION

Measurement of GH within 1 week after surgery is highly predictive for outcome of surgery for acromegaly. Specifically, an early mean GH </= 4.8 mU L-1 is as predictive for a satisfactory effect of treatment as a normalized IGF-1 3 months after surgery. Early postoperative GH values > 4.8 mU L-1 have a high sensitivity for persistent or recurrent disease in both the short- and long-term perspectives, but lower predictive value. The usefulness of the TRH test can be questioned.

Effect of glucocorticoids on the paradoxical growth hormone response to thyrotropin-releasing hormone in patients with acromegaly

It has been hypothesized that in acromegalic patients, as well as in normal subjects, acute increases in serum cortisol levels may cause an enhancement of hypothalamic somatostatin secretion, which in turn may be responsible for the glucocorticoid-mediated growth hormone (GH) inhibition. The aim of this study was to investigate short-term effects of an intravenous (i.v.) infusion of hydrocortisone on the GH response to thyrotropin-releasing hormone (TRH) in acromegaly. We studied six adult patients with active acromegaly. The group was composed of four women and two men with a mean age of 55.8 +/- 6.4 years (range, 27 to 68) and a mean body mass index of 26.7 +/- 1 kg/m2 (range, 23.3 to 30). All patients underwent the following treatments: (1) hydrocortisone alone: a bolus i.v. injection of hydrocortisone succinate 100 mg in 2 mL saline at time -60 minutes, followed by a 120-minute i.v. infusion of hydrocortisone succinate 250 mg in 250 mL saline from -60 to 60 minutes; (2) TRH+hydrocortisone: a bolus i.v. injection of TRH 200 micrograms 60 minutes after initiation of a 2-hour hydrocortisone infusion; (3) TRH alone: a bolus i.v. injection of TRH at time 0, 60 minutes after initiation of a 2-hour saline infusion. In all six patients, TRH induced large GH increases (absolute peak GH level, 58.1 +/- 23.2 micrograms/L; maximum % GH change with respect to baseline, 1,397.8% +/- 807.8%; range, 205% +/- 5,219%).(ABSTRACT TRUNCATED AT 250 WORDS)

Relationships between insulin-like growth factor-1 levels and growth hormone concentrations during diurnal profiles and following oral glucose in acromegaly

OBJECTIVE

The aim of this study was to refine the biochemical definition of disease activity in acromegaly by comparing serum growth hormone (GH) measurements during a 10-hour day profile with serum GH values during an oral glucose tolerance test.

DESIGN

Using plasma insulin-like growth factor-1 (IGF-1) levels as a measure of disease activity, serum GH data from a day profile and from an oral glucose tolerance test were compared.

PATIENTS

Thirty-five acromegalic patients were studied, 13 of whom had serum GH measured during a day profile and 22 during an oral glucose tolerance test. In addition, basal plasma IGF-1 levels were estimated in all acromegalic patients, and in 24 normal subjects.

MEASUREMENTS

Following acid-ethanol extraction of the plasma samples, IGF-1 levels were measured by radioimmunoassay using a polyclonal antibody. In a day profile, six to eight blood samples for serum GH estimation were taken at hourly intervals during the day; during an oral glucose tolerance test samples for serum GH estimation were taken in the fasting state and every 30 minutes for 2 hours and measured by a two-site IRMA for GH.

RESULTS

Ninety-four per cent of acromegalic patients with raised plasma IGF-1 levels had serum GH concentrations > 10 mU/l whilst 98% of acromegalic patients with plasma IGF-1 levels in the normal range had serum GH concentrations < 6 mU/l. A highly significant positive correlation was found between the mean serum GH concentrations (r = 0.67), the minimum serum GH concentration (r = 0.65) and the area under the GH curve (r = 0.66) estimated during an oral glucose tolerance test and plasma IGF-1 concentrations. The relations between identical indices of serum GH concentration measured during a day profile and plasma IGF-1 levels, although significant, show a less powerful correlation. The relation between serum GH and plasma IGF-1 levels describes a curvilinear model, plasma IGF-1 levels exhibiting a plateau at serum GH concentrations > 40 mU/l but maintaining a linear relationship with serum GH levels < 20 mU/l.

CONCLUSIONS

A highly significant correlation exists between plasma IGF-1 levels and various parameters of serum GH levels in acromegalic patients. Hormonal assessment of disease activity in acromegaly is more accurately reflected by the serum GH concentration during an oral glucose tolerance test rather than by the serum GH level during a day profile. Normalization of plasma IGF-1 levels is rarely achieved unless the mean serum GH level is reduced to < 6 mU/l.

Transsphenoidal adenomectomy for growth hormone-secreting pituitary adenomas in acromegaly: outcome analysis and determinants of failure

The results of transsphenoidal adenomectomy for growth hormone (GH)-secreting pituitary adenomas in acromegaly performed over a 17-year period were analyzed retrospectively to determine which preoperative factors significantly influenced the long-term surgical outcome. These variables were then used to develop a logistic regression model to determine the probability of surgical failure. The series consisted of 103 patients. Long-term follow-up study (mean duration 102 +/- 64 months) was performed to derive outcome analysis and determinants of failure. Surgical control was defined as a long-term postoperative serum basal GH level of less than 5 micrograms/liter, a long-term postoperative serum somatomedin C (SM-C) level of less than 2.2 U/ml, and a favorable clinical response. Eighteen (17.5%) patients did not meet these criteria. The overall control rate by the GH criteria was 81.3% and by the SM-C criteria 76.2%. By multivariate logistic regression analysis, tumor stage was the strongest predictor of outcome (p < 0.05). The preoperative GH level, tumor grade, and preoperative SM-C level were significant univariate predictors (p < 0.05). There were statistically significant differences in mean preoperative GH and SM-C levels (p < 0.05, t-test) and tumor stage (p < 0.05, chi-squared test) between patients whose acromegaly was controlled by surgery and those whose acromegaly was not. Furthermore, estimates were derived of the probability of surgical failure based on preoperative GH level, preoperative SM-C level, and tumor grade and stage. The authors believe these findings will enhance clinical decision-making for neurosurgeons considering transsphenoidal microsurgery in patients with acromegaly.

Early postoperative basal serum GH level and the GH response to TRH in relation to the long-term outcome of surgical treatment for acromegaly: a report on 39 patients

During a 10-year period 39 patients with acromegaly, aged 23-73 years, underwent selective adenomectomy via a trans-sphenoidal or transfrontal (one case) approach. Six to 12 months after the operation, the serum level of growth hormone (GH) was reduced to less than 5 micrograms l-1 in 28 patients (74%) in at least two of three random samples and/or suppressed to less than 3 micrograms l-1 during an oral glucose load, thus fulfilling the commonly used criteria for a successful operation. In 10 patients these criteria for adequate GH reduction were not fulfilled, but their median S-GH level was reduced from 38 to 11 micrograms l-1 (P less than 0.01) after the operation. Surgery was successful in 11 of 13 (85%) patients with a microadenoma (less than 10 mm in diameter), in 10 of 14 (71%) patients with an adenoma of diameter greater than 10 mm but still enclosed in the sella, and in seven of 11 (64%) patients with locally invasive tumours. Impaired pituitary function was observed in 23% of the patients after surgery, independent of tumour size. In one patient the postoperative period was complicated by a lethal intracranial infection. During follow-up for 1-10 years, four patients relapsed, after 1, 1.5, 6 and 9 years, respectively. Patients for whom surgery appeared to have been ineffective at the evaluation 6-12 months postoperatively, or who later relapsed were identified by early (within 7 d) postoperative serum GH with a sensitivity of 90%. The accuracy for identification of a satisfactory outcome of surgery was 85%, and the predictive value was 90%. The corresponding values for the GH response to TRH measured 6-12 months postoperatively were 47, 40 and 54%, respectively. It is concluded that the basal level of serum GH measured 1-7 d postoperatively has higher sensitivity and specificity than the GH response to TRH 6-12 months postoperatively for evaluation of the effect of surgery on GH overproduction, and that it has a higher predictive power with regard to the long-term outcome of surgery for acromegaly.

Evaluation of selective transsphenoidal adenomectomy by endocrinological testing and somatomedin-C measurement in acromegaly

A series of 29 previously untreated patients with acromegaly underwent transsphenoidal adenomectomy. Pre- and postoperative evaluation consisted of measuring growth hormone (GH) secretory dynamics during an oral glucose tolerance test (OGTT), the insulin hypoglycemia test, and the thyrotropin- and gonadotropin-releasing hormone (TRH/GnRH) test, and by obtaining the basal somatomedin-C level. After surgery, clinical and biochemical amelioration was achieved in all but two patients. In the whole group, basal GH and somatomedin-C levels decreased from a mean (+/- standard error of the mean) of 52.3 +/- 12.7 to 11.1 +/- 6.3 ng/ml and from 7.6 +/- 0.7 to 2.5 +/- 0.5 U/ml, respectively. Application of different criteria of cure revealed that 19 patients (66%) had basal GH levels below 5 ng/ml, 17 patients (59%) had normal somatomedin-C values, 16 patients (55%) had complete GH suppression (less than 1 ng/ml) during OGTT, and 13 patients (45%) met the above-mentioned criteria with disappearance of the paradoxical GH response to TRH/GnRH test. Evaluation of GH secretion by insulin hypoglycemia testing was useless in assessing the outcome after neurosurgery. When only patients with a normal somatomedin-C level and complete GH suppressibility during OGTT were considered "cured," the main favorable prognostic factor was intrasellar tumor localization, since 15 (75%) of 20 patients were "cured," as opposed to only one (11%) of nine with extrasellar extension of the adenoma. During the follow-up period, no tumor recurrence was detected in any of the "cured" patients. In these subjects somatomedin-C levels remained stable in all except two patients, who showed a slow increase within the normal range of somatomedin-C concentration. These data confirm that transsphenoidal surgery is the most effective form of treatment in previously untreated acromegalic patients and that normalization of somatomedin-C levels reflects normal GH secretion. Measurement of somatomedin-C could replace more extensive endocrinological testing during monitoring of treated acromegalic patients.

Results of transsphenoidal microsurgery for growth hormone-secreting pituitary adenoma in a series of 214 patients

Of 214 patients with acromegaly who underwent transsphenoidal microsurgical resection of a pituitary adenoma, 54% had growth hormone (GH) levels below 5 ng/ml and 74% had levels less than 10 ng/ml immediately after surgery. Among the 174 patients who could be contacted for long-term follow-up review (average duration 76 months), most recent GH determinations were available for 165. Of these 165 patients, 131 (79.4%) have a GH level less than 5 ng/ml and 153 (92.7%) have a level below 10 ng/ml; these represent 75.3% and 87.9%, respectively, of the total 174 patients reviewed. Fifty-two patients received postoperative radiation therapy. Nine patients underwent reoperation. There were five cases of tumor recurrence following an apparent surgical cure (4.3%), nine new instances of anterior pituitary hypofunction (5%), and five failures of multimodality therapy (2.3%). There were no perioperative deaths, five cases of cerebrospinal fluid leak requiring surgical repair (2.2%), and four cases of postoperative meningitis (1.8%). Permanent diabetes insipidus did not occur. Two of 52 patients who were irradiated postoperatively had severe complications; 23 (54.8%) of 42 patients who were available for follow-up evaluation had developed panhypopituitarism; and eight (19%) of 42 had normal pituitary function an average of 44 months postirradiation.

The influence of diabetes mellitus on thyrotropin response to thyrotropin-releasing hormone in untreated acromegalic patients

Impairment of thyrotropin (TSH) response to thyrotropin-releasing hormone (TRH) has been documented in patients with uncontrolled diabetes mellitus (DM). In acromegalic patients, however, there have been no data regarding TSH secretion studied taking the existence of DM into consideration. Therefore, we investigated the TSH response to TRH [expressed as TSH increment (delta TSH)] in 14 untreated acromegalic patients, who did not show the suprasellar extension of adenoma, divided into two groups on the basis of either presence or absence of uncontrolled DM, and in 28 normal subjects. The mean max delta TSH was significantly reduced (p less than 0.02) in acromegalic patients despite similar mean serum T4 and free T4 index (FT4l) levels. Furthermore, the mean basal and max delta TSH in 7 patients with DM (FBS, 120-300 mg/dl; HbA1, 8.8-15.2%) were significantly lower than those in 7 patients without DM (p less than 0.05 and p less than 0.02, respectively) despite similar the mean serum T3, T4, FT4l, growth hormone (GH) and prolactin (PRL) levels and sellar volume. In 4 patients with DM the TSH response to TRH 6-8 weeks after insulin therapy, when their HbA1 levels were normal, increased compared to that before insulin therapy. The mean max delta TSH after selective adenomectomy in 8 patients (3 in DM group and 5 in non-DM group), whose fasting basal GH fell to less than 5 ng/ml, was almost identical to that in normal subjects. In conclusion, the present study suggests that the abnormality in TSH secretion in acromegalic patients may be increased by the existence of uncontrolled DM.

Postoperative plasma GH levels and restoration of GH dynamics in acromegalic patients surgically treated by the transsphenoidal approach

In 44 patients with acromegaly treated by transsphenoidal pituitary microsurgery, the relationship between changes in pre- and post-operative GH dynamics and postoperative fasting plasma GH levels was examined to clarify which is the optimal approach for evaluating postoperative removal of the tumour. TRH, LHRH and bromocriptine tests, which act directly on the pituitary somatotroph, and the oral glucose tolerance test (oGTT) and insulin tolerance test (ITT), which act via hypothalamus, were carried out pre- and post-operatively. Abnormal responses postoperatively were found in most patients with fasting postoperative plasma GH over 5 ng/ml. In 24 patients with postoperative fasting plasma GH level of 5 ng/ml or below, 7 of 17 (41%) showed abnormal responses in the TRH test, 2 of 5 (40%) in the LHRH test and 3 of 13 (23%) patients in the bromocriptine test. All patients with a fasting plasma GH level less than 10 ng/ml, except for those with panhypopituitarism, showed normal responses to ITT and the paradoxical increases with the oGTT were absent. These results indicate that abnormal responses caused by a direct action on adenoma cells do not necessarily disappear even when the fasting plasma GH level is below 5 ng/ml. Abnormal responses caused by indirect actions, through the hypothalamus, disappear when the level is less than 10 ng/ml.

Long-term results of transsphenoidal pituitary microsurgery in 60 acromegalic patients

Sixty patients with clinically and biochemically active acromegaly were treated by transsphenoidal surgery. All patients underwent a full assessment of pituitary function both preoperatively and postoperatively; these studies were repeated 6 months after surgery and every year, when possible. The mean follow-up period was 3.3 years (range 0.5-7 years). The GH level normalized in 62% of patients after surgery. A paradoxical reaction of GH to TRH was present in 35 patients before surgery and had normalized in 17 after surgery. Large tumours were associated with higher GH levels than smaller tumours. A prognostic factor in terms of normalization of both the GH level and an eventual paradoxical reaction to TRH or a glucose challenge was a low preoperative GH level. Three out of seven patients with either a positive postoperative TRH test but a normal GH level, or a slightly elevated GH level suffered a biochemical and clinical recurrence and two of them underwent reoperation. In contrast, when the TRH test had normalized (always in association with normal GH levels) no recurrence was found. The impact of surgery on the other pituitary functions was generally slight and the numbers of patients with preoperative and postoperative impairment were about equal. Postsurgical radiation therapy was administered to patients with an elevated GH level, a non-normalized TRH test irrespective of whether the GH level had normalized, or local invasion of the tumour. In 11 out of 17 patients with elevated GH levels after surgery, normalization was achieved by radiation therapy after a mean period of 2.7 years. The incidence of pituitary failure after irradiation appeared to be high; gonadal function in men and the GH reserve function were especially vulnerable. From this study we conclude that in many cases the adenoma can be removed effectively, without compromising the other pituitary functions. However, a substantial number of the patients require additional radiation therapy, leading to an inevitable loss of other pituitary functions.

Long-term growth hormone responses to nonspecific hypothalamic hormones in acromegalic patients

Nonspecific hypothalamic hormones such as thyrotropin-releasing hormone or luteinizing hormone-releasing hormone, or both, elicited abnormal growth hormone responses in 73 of 108 (67.6%) acromegalic patients. After transsphenoidal adenomectomy, the provocative tests using these hormones were repeated in 26 patients with abnormal preoperative growth hormone responses to study variations in these responses during a 1-8-year observation period (average duration, 4 years). After surgery, 7 of the 26 patients regained normal basal growth hormone levels (less than 5 ng/mL) and manifested normal responses to the hypothalamic hormones. During the postoperative observation period, their basal growth hormone levels remained normal as did their responses to provocation with hypothalamic hormones, confirming that the adenoma had been completely resected. Eight other patients demonstrated normal growth hormone levels after surgery; however, they continued to have abnormal responses to provocation with hypothalamic hormones, suggesting the presence of residual adenomatous tissue in the gland. These patients manifested no marked increase in basal or peak growth hormone levels during the follow-up period (from less than 1 to less than 7.5 years) and they were all in clinical remission without any other treatment. Only one incompletely adenomectomized patient who had received no additional treatment experienced regrowth of the tumor. The main factor affecting the surgical results appears to be the preoperative basal growth hormone level, because abnormal growth hormone secretion ceased in all patients who had manifested preoperative levels below 45 ng/mL. Technical refinements of the operative procedure are another important factor in the postoperative outcome. Peritumoral tissue resection after simple selective adenomectomy is mandatory for better surgical results. Our studies indicate that fairly good results can be obtained without risk of the recurrence of the tumor or regrowth, when postoperative growth hormone levels are below 5 ng/mL and that the results are not affected by the postoperative growth hormone responses to provocation with hypothalamic hormones.

Growth hormone producing pituitary adenomas with concomitant hypersecretion of prolactin are particularly sensitive to photon irradiation

The effect of photon irradiation (50 Gy with a 3-field technique in fractionated doses) on growth hormone (GH), prolactin (PRL), and somatomedin A (SMA) was studied in 25 patients with acromegaly after previous unsuccessful surgery. In patients with concomitant hypersecretion of PRL, the GH reduction was 70 +/- 22% 1 year and 88 +/- 10% 3 years after radiotherapy. The corresponding reductions in patients with isolated GH hypersecretion were 42 +/- 25% and 60 +/- 22%. The reduction of GH levels was most notable the first year after radiotherapy in 16 patients and during the second year in 7 patients. Serum PRL decreased after radiotherapy in all patients with hyperprolactinemia, whereas PRL in normoprolactinemic patients showed inconsistent changes, including PRL increments in 8/12 patients. The effect of radiotherapy on GH and PRL was not correlated to the irradiation target volume or the cumulative radiation effect. SMA levels decreased after radiotherapy, but became normal only in 3 patients, all with pretreatment GH less than 5 micrograms/l. Radiotherapy, 3 years after treatment, appeared to be equivalent to the primary surgical intervention in reducing GH and SMA in patients with acromegaly due to advanced macroadenomas. Patients with concomitant hyperprolactinemia showed increased sensitivity to radiation compared to normoprolactinemic patients with acromegaly.

Recent developments in the treatment of acromegaly

In acromegaly the microsurgical transsphenoidal removal of the pituitary adenoma has become the most widely used method of treatment. In experienced hands, the therapeutic goal of rapid normalization of hormone excess and preservation of pituitary function can be achieved in most of the patients if the tumours are not too large. Medical treatment or radiotherapy alone, or in combination, are less successful for primary treatment. They are indispensable as alternative therapy in those patients not suitable for operation, and as additional methods after incomplete tumour removal. Large invasive adenomas still present a challenge for further improvement of therapeutic facilities. Intraoperative GH-measurements, as recently introduced by us, help to identify tumour residues and justify additional surgical exploration at higher risk.

Transsphenoidal surgery for acromegaly--long-term results in 100 patients

A series of 100 patients with acromegaly who were operated on using the transsphenoidal microsurgical approach is presented along with a review of the literature. Emphasis is placed on long-term follow-up to assess the value of the technique. The authors caution against early normalization of growth hormone as a criterion for biologic cure in that cases of late recurrence are presented. It is proposed that 5 ng/mL baseline growth hormone values with normal dynamic testing is the most reliable way to ascertain biologic cure. Using these criteria, a cure rate of 78% for enclosed and 33% for invasive adenomata was obtained. No long-term recurrence was seen in patients considered cured along these lines.

Surgical therapy of lesions within the hypothalamic region

On one hand pituitary microadenomas with autonomous character and those, which had been influenced by hypothalamic disorders, are summarized and discussed. On the other hand, the neurosurgical management of tumours, adjacent to or involved with the hypothalamus, are described. Endocrinologically active pituitary adenomas are characterized by their hormone excess of ACTH, GH, and prolactin. In Cushing's disease endocrine and clinical remission occurred in 74%. 3 patients out of this group showed a reincrease of ACTH after a period of remission, indicating a possible hypothalamic influence. In acromegaly the hypothalamic influence is also discussed. One patient with an ectopic GRF-producing tumour showing a reincrease of GH levels after successful transsphenoidal adenomectomy has been described. In microprolactinomas, 7 patients out of 45 showed a reincrease of prolactin-levels after a period of normalization, we also discussed hypothalamic disorders. Tumours with suprasellar extension such as macroadenomas without endocrine activity and meningiomas are removed nowadays with minimal risk for the life of the patients. In craniopharyngiomas radical excision is accompanied by a high risk of hypothalamic defects caused by mechanical lesions and possible secondary vasospasm. Finally the excision of a hamartoma growing from the floor of the third ventricle into the interpeduncular cistern is discussed. Up to now the successful excision could be documented by endocrinological data, which give no sign of further growth of the hamartoma.

Disorders of prolactin and growth hormone secretion

A large range of tests is now available to help us understand, diagnose and manage GH-related growth disorders. The traditional provocative tests of GH secretion will identify short children with severe GH deficiency. However, evidence is emerging that these pharmacological tests may not be sufficiently sensitive to identify some subjects with GH deficiency arising from neurosecretory disturbance of GH release. There is a need for a simple sensitive test that will detect subtle GH secretion of this type. hGRF administration is a reliable test of GH reserve and, when used in combination with conventional tests, may help to identify GH-deficient children with hypothalamic GRF deficiency. Whether the GH responses following GRF administration reflects physiological GH secretory activity needs to be established. The diagnosis of acromegaly is made on clinical grounds. The abnormal GH responses to glucose and TRH support the diagnosis, but by themselves should not be considered to be diagnostic of acromegaly. An elevated Sm C level also helps to establish the diagnosis, although Sm C concentrations may be elevated to the same degree in pregnancy and during puberty. The use of Sm C to monitor disease activity remains to be established. Circulating GRF levels should be measured in patients with acromegaly so that ectopic production of GRF can be identified.

Investigation of hypothalamic-pituitary disease

It can be readily appreciated from the preceding discussion that many endocrine and non-endocrine tests are available for the evaluation of patients with suspected hypothalamic-pituitary disease. The endocrine evaluation of these subjects should be tailored according to the type and extent of pathology suspected (see Tables 2 and 3). For patients with pituitary adenomas and clinical features of hyperpituitarism, such as hyperprolactinaemia, Cushing's disease or acromegaly, the initial tests should be directed at the hormone whose excess is suspected. For example, a glucose suppression test for acromegaly or dexamethasone suppression test for Cushing's disease should be performed early in the evaluation. The possibility of deficiencies of the other pituitary hormones should then be addressed in patients with secretory tumours, but initially in those with apparent non-functioning adenomas. In patients with large macroadenomas pituitary hormone deficiencies are almost invariable with GH and FSH/LH being the most commonly affected, followed by TSH and ACTH in that order (Snyder et al, 1979a; Valenta et al, 1982). Basal thyroid function tests, serum oestradiol or testosterone, and basal gonodotrophins should be routinely obtained in patients with macroadenomas. Additionally, the integrity of the pituitary-adrenal axis should be determined and an overnight water deprivation test for assessment of neurohypophyseal function is also recommended. GH stimulation testing is valuable as a test of pituitary function in patients with suspected pituitary tumours since GH reserve is lost very early in the development of hypopituitarism. Evaluation of the pituitary-thyroid axis with TRH or the pituitary gonadal axis with LHRH generally provides limited additional information of diagnostic value in individual patients with macroadenomas. However, the 'paradoxical' responses to TRH and LHRH may be useful as a biological marker following therapy in patients with GH- or ACTH-secreting tumours. In patients with microadenomas, pituitary hormone deficiencies are uncommon (Valenta et al, 1982). Despite this observation, it may be beneficial to determine basal thyroid levels, gonadotrophin levels, serum testosterone or oestradiol levels, and the response to an overnight metyrapone test in such patients to provide a baseline for future care.(ABSTRACT TRUNCATED AT 400 WORDS)

Clinical use of pre- and postsurgical evaluation of abnormal GH responses in acromegaly

The criteria by which acromegalic patients are considered "cured" after surgical therapy are still controversial. Since the abnormal growth hormone (GH) increase after the administration of some agents has been demonstrated to be characteristic of the tumoral somatotrophs, its disappearance after surgery may be taken as an index of the complete removal of the tumor. Serum GH increases after thyrotropin-releasing hormone (TRH, 200 micrograms intravenously), gonadotropin-releasing hormone (Gn-RH, 100 micrograms intravenously), and sulpiride (100 mg intramuscularly) injected during dopamine infusion (DA-Slp test), were evaluated in 68 acromegalic patients before and after transnasosphenoidal adenomectomy, and every 12 to 18 months during a follow-up period of 6 months to 11 years (average 42 months). Forty-two patients had abnormal responses to at least one test before surgery: 32 out of 68 (47%) to TRH, six out of 40 (15%) to Gn-RH, and 20 out of 28 (71%) to the DA-Slp test. Of 18 patients who underwent all three tests, 78% had abnormal responses to at least one of them. Twenty-three patients became unresponsive after surgery, and none of them had a recurrence or became abnormally responsive again during the follow-up period. Three out of six patients with postoperative serum GH levels between 5.1 and 10 ng/ml and three out of six patients with postoperative serum GH levels between 2.1 and 5 ng/ml remained abnormally responsive: one of them relapsed 1 year after the operation. The abnormal responses were lost in all 11 patients whose postoperative serum GH levels were below 2 ng/ml, and abnormal responses were maintained in all the patients in whom surgery was considered unsuccessful because postoperative serum GH levels were higher than 10 ng/ml. The TRH, Gn-RH, and DA-Slp tests should thus be considered useful tools in verifying the total removal of an adenoma. The reappearance of active acromegaly in the patient with low postoperative GH levels, who was still responsive to TRH, should be regarded as a reactivation and not a true recurrence of the disease.

Treatment of acromegaly by trans-sphenoidal operation, 90-yttrium implantation and bromocriptine: results in 230 patients

Two hundred and thirty patients with acromegaly were diagnosed and treated in a prospective cooperative study in twelve university clinics. Primary treatment was: trans-sphenoidal surgery (152 patients), trans-sphenoidal surgery with additional cryotherapy (eighteen patients), Yttrium-90-implantation (thirty patients), bromocriptine (thirty patients). The results of endocrine assessment before treatment and 6 months after operation, 90-Y implantation or commencement of bromocriptine therapy are reported. The best results (low GH, no or little deterioration of pituitary function, low complication rate) were achieved by trans-sphenoidal surgery, especially in patients with intrasellar tumours (basal GH less than 5 ng/ml in 59.7%). Results were less good with increasing tumour size. Additional cryosurgery was accompanied by a high rate of anterior pituitary insufficiency and is no longer employed. Yttrium-90-implantation resulted in less improvement in GH levels (basal GH less than 5 ng/ml in 51.7% of patients with intrasellar tumours), a high rate of pituitary insufficiency and more complications. Bromocriptine treatment was least effective in lowering GH concentrations (basal GH less than 5 ng/ml in 33% of patients with intrasellar tumours). Different criteria for treatment success were compared. In the entire group, basal GH concentrations below 5 ng/ml were attained in 51.7% of all patients whose values were higher than this prior to treatment. Suppressibility of GH below 2 ng/ml during glucose loading occurred in only 34.9%. An abnormal GH response to TRH/LHRH was present in 47.2% before and in 43.4% after/during treatment. The prognostic significance of this latter finding must be evaluated by further study.

Pituitary surgery for endocrine disorders

The use of pituitary surgery for patients with over-production of growth hormone, corticotrophin and prolactin is reviewed. The value of specialized neuroradiological techniques is discussed including computerized tomography, air-encephalography and cavernous sinus venography. The indications for transcranial as opposed to trans-sphenoidal surgery are considered. The place of trans-sphenoid surgery in the treatment of acromegaly is emphasized and the indications for surgical treatment are reviewed. The two syndromes due to over-production of ACTH are considered--Cushing's disease and Nelson's syndrome. The increasing use of pituitary surgery for the treatment of Cushing's syndrome due to increased ACTH production is noted, but a warning is given about the small ACTH-secreting pulmonary carcinoid tumour that may closely mimic Cushing's disease. The difficulties encountered in trying to treat patients with Nelson's syndrome are stressed. It is recommended that in the rate case where total adrenalectomy is required in Cushing's disease, pituitary irradiation should be given before or shortly after adrenalectomy. The present position relating to the surgical treatment of the small prolactin-secreting pituitary tumour is reviewed. Published data and personal experience suggests that for many of these patients, treatment with bromocriptine is preferable to trans-sphenoidal surgery. Large prolactinomas usually need transfrontal surgery and X-ray therapy, sometimes followed by bromocriptine treatment. The need for steroid cover for pituitary surgery is discussed and it is suggested that a glucocorticoid with less salt-retaining action than cortisol should be used. The importance of post-operative endocrine assessment is emphasized and a convenient method suggested. The incidence of complications after transsphenoidal surgery is low, although panhypopituitarism occurred in 14% of the cases reported.