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

Epidemiology and long-term survival in acromegaly. A study of 166 cases diagnosed between 1955 and 1984

In 1985, a follow-up investigation was performed of all patients with acromegaly (n = 166, 89 women and 77 men) seen over a 30-year period (1955-1984) at our Endocrine Unit, referral centre for the western region of Sweden (population 1.5 million). At the end of 1984, the prevalence of the disease was 6.9 per 10(5) inhabitants, the average incidence per year was 3.3 per million people. Mean age at diagnosis was 46.3 years and at death (n = 62) 64.1 years. About one-third of the patients (50/153), in whom it had been possible to estimate the total duration of the disease, had survived for more than 25 years. Mortality was, however, increased compared to the normal population. The observed number of deaths from vascular and malignant disorders was 32 and 15, respectively, compared to the expected numbers 9.0 (p less than 0.001) and 5.6 (p less than 0.01).

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.

Thyrotropin-releasing hormone increases serum levels of growth hormone-releasing hormone and growth hormone in patients with acromegaly

The effect of intravenous injection of thyrotropin-releasing hormone (TRH) on the plasma concentrations of growth hormone (GH) and growth hormone-releasing hormone (GHRH) was studied in seven patients with acromegaly and in five control subjects. TRH had no effect on plasma GH or GHRH in the five control subjects. A 'paradoxical' increase in plasma GH in response to TRH was observed in four of the seven patients with acromegaly. In these four patients plasma GHRH also increased in response to TRH. No TRH-induced increase in GHRH levels was observed in the other three patients with acromegaly who did not display an increase in GH in response to TRH. The present results imply that GHRH may be involved in the plasma GH response to TRH 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.

The growth hormone, prolactin and TSH response to TRH and L-dopa in patients with hyperprolactinaemia and a normal-sized sella turcica may denote a pituitary adenoma

Forty-one patients with hyperprolactinaemia and suspected prolactinomas were studied. Growth hormone (GH) and thyrotropin (TSH) secretory patterns after thyrotropin releasing hormone (TRH) were affected in the majority of patients. The disturbances were observed regardless of tumour size as indicated by the radiological sella size. In patients with hyperprolactinaemia and normal-sized sella turcica, an abnormal GH and TSH response to TRH can be helpful in the diagnosis of a microadenoma. The hyperprolactinaemia per se and its effect on dopaminergic hypothalamic neurones may be the cause of the GH and TSH response. By contrast, many patients with macroprolactinomas showed insufficient GH secretory capacity.

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.

Investigation of the criteria for assessing the outcome of treatment in acromegaly

The outcome of treatment in acromegaly is usually assessed by measuring plasma concentrations of growth hormone (GH)--either basal spontaneous levels or during hyperglycaemia. There is no consensus on how cure should be defined. Many studies have considered basal plasma growth hormone concentrations below 20 mU/l (10 ng/ml) as proof of cure, although some recent studies have applied lower values. At present a limit of 10 mU/l (5 ng/ml) seems to be accepted as evidence of cure. We have studied 28 acromegalic patients after transsphenoidal adenomectomy. Plasma GH concentrations (basal and during hyperglycaemia) as well as plasma somatomedin C (SMC) concentrations were measured and compared to the clinical symptoms. There was a close correlation between plasma GH and SMC concentrations (except when plasma GH levels were low) and between the clinical assessment and SMC concentrations. Very low plasma GH levels (less than 1 mU/l or 0.5 ng/ml) were associated with normal SMC values and clinical cure, high GH levels (greater than 10 mU/l or 5 ng/ml) with elevated SMC levels and persisting acromegaly. Moderately elevated plasma GH concentrations (1.9-9.6 mU/l) did not allow any conclusions on the outcome of treatment as assessed from SMC determinations and clinical evaluation. It is concluded that the usual criteria for cure in acromegaly may not be sufficiently strict.

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.

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.

DNA pattern of human pituitary tumors

The tumor tissue from 62 consecutive patients with pituitary adenomas was analyzed with regard to ploidy and percentage of cells in different phases of the cell cycle by use of flow-cytofluorometry. In six of 62 cases, two tumor-cell populations were identified; therefore the study material comprised 68 cell lines. Approximately half of the cell lines were diploid (33 of 68, or 49 per cent); five of 68 (7 per cent) were hypodiploid, and 30 of 68 (44 per cent) were hyperdiploid-aneuploid. A low occurrence of aneuploid cell lines appeared in hormonally nonsecreting tumors (22 per cent). An aneuploid DNA pattern was predominantly found in prolactinomas (70 per cent). In acromegaly, tumors secreting growth hormone had only an aneuploid DNA pattern in 41 per cent of the cases, whereas 67 per cent of the tumors with concomitant secretion of growth hormone and prolactin were aneuploid. The latter group also comprised the largest number of adenomas with two cell lines and all but one hypodiploid tumor. Most tumors with an aggressive clinical course were either aneuploid or diploid but with a high percentage of proliferating cells.