Failure of radiotherapy in acromegaly.

BACKGROUND: Recent data has raised skepticism regarding the long-term effectiveness of radiotherapy (RxT) in acromegaly and its role as an ancillary tool to neurosurgery (Tx). PATIENTS: We evaluated 72 acromegalic patients previously submitted to RxT. Data were discarded in 23 patients, who were lost to follow-up, operated on after RxT or irradiated with techniques different from external conventional fractionated RxT. Among the remaining 49 (five with mixed GH-prolactin adenoma), 34 were irradiated after surgical failure and 15 as primary treatment. A second cycle of RxT was administered in two. RESULTS: (i) GH/IGF-I. After a median follow-up of 14 years (range 3-41), normal age-matched IGF-I levels were reached in eight patients (16%) after 10 years, and GH levels <2.5 microg/l in six (12%) after 9 years. The rate of persistently pathological hormonal levels was still 90% at 25 years. All patients with GH/IGF-I normalization had undergone irradiation without any antisecretory drug. Neither basal GH nor tumor size affected the outcome of RxT. In three patients (6%) a relapse/worsening occurred. (ii) Tumor size. Tumor shrank after 8.5 years in 24 patients (49%), in nine of whom during GH-suppressive treatment. Tumor shrinkage was not predictive of hormonal normalization. (iii) Side-effects. Hypopituitarism was diagnosed in four patients (selective in three and global in one) and GH deficiency in one. Three patients had neurological side-effects and meningioma was shown in two patients. CONCLUSION: RxT is unable to cure acromegaly, because it seldom achieves hormonal normalization even after a very prolonged follow-up. Concomitant antisecretory treatment seems to counteract its effects. RxT can still play a role in those patients with large tumor remnants, because of its capacity to shrink tumor size.

From macroprolactinoma to concomitant ACTH-PRL hypersecretion with Cushing's disease.

Multiple pituitary hormone hypersecretions have been already described, but the combination of PRL and ACTH excess is rare. This report deals with a 42-yr-old woman affected by macroprolactinoma (PRL 12,720 microg/l, huge tumor with extrasellar extension at imaging). After one year on dopaminergic treatment causing PRL normalization and tumor shrinkage, she developed hypercortisolism (UFC 1,000 microg/24 h, ACTH 200 ng/l). Cushing's disease was diagnosed. After neurosurgery (at immunocytochemistry mixed ACTH-PRL adenoma was shown) hypercortisolism remitted, whereas pathological hyperprolactinemia with tumor remnant in cavernous sinus persisted and hypopituitarism developed. The patient reported seems atypical for the following reasons: 1) the concomitant PRL and ACTH hypersecretions; 2) the clinical presentation with hypercortisolism following hyperprolactinemia; 3) the surgical cure of hypercortisolism with persisting hyperprolactinemia.

A comparison between octreotide-LAR and lanreotide-SR in the chronic treatment of acromegaly.

BACKGROUND: At present long-acting somatostatin analogs represent the first-line medical treatment of acromegaly. These drugs produce stable suppression of GH in most sensitive patients and IGF-I normalization in many; they also increase the compliance of acromegalic patients. The recent availability of octreotide (OC)-LAR, a somatostatin analog to be administered at 28-day intervals, has prompted us to compare, in the same group of patients, its effects and those of another somatostatin analog already available, lanreotide-SR (LSR, to be administered at 14-day intervals). PATIENTS: Twelve somatostatin analog-sensitive acromegalic patients with active disease were enrolled in a prospective open sequential study after giving their informed consent. After chronic treatment with LSR (6-24 months), the patients were changed to treatment with OC-LAR, without wash-out. LSR had been administered at individually tailored dosages (30 mg i.m. at 7-21-day intervals, median 10 days - every 7 days in seven patients, 10 days in two patients, 14 days in two patients and 21 days in one patient) according to GH and IGF-I responses. Disease stability was obtained, as shown by maximal GH/IGF-I suppression without any significant hormonal change between the last two control measurements. OC-LAR was administered i.m. at 28-day intervals six times at the dosage of 20 mg for the first three times and 10 or 30 mg for the last three times (according to individual GH/IGF-I responses). GH (mean of three, hourly samples) and IGF-I concentrations were evaluated on the same day as each administration of the drug, before its injection. RESULTS: GH and IGF-I values were significantly decreased by LSR treatment. GH decreased from 41.6 +/- 14.6 microg/l (mean +/- s.e.) to 7.2 +/- 1.5 microg/l (P < 0.02), whereas IGF-I values declined from 959 +/- 95 microg/l to 460 +/- 61 microg/l (P < 0.00001), expressed as absolute values, and from 287 +/- 30% to 137 +/- 19% expressed as percentage of the upper limit of normal range (% ULNR). At the end of the last cycle, OC-LAR treatment achieved a significant further suppression both in GH (to 5.1 +/- 1.1 microg/l, P < 0.05 compared with LSR) and in IGF-I concentrations (to 374 +/- 60 microg/l, P<0.05 compared with LSR, and to 112 +/- 19% as % ULNR). LSR decreased GH concentrations to less than 2.5 microg/l in one patient and normalized IGF-I concentrations in four patients. OC-LAR decreased GH concentrations to less than 2.5 microg/l in four patients and normalized or near-normalized IGF-I concentrations (i.e. to < 110% ULNR) in eight patients. CONCLUSIONS: These preliminary results show that the once-monthly OC-LAR administration schedule proved more efficacious than LSR given every 7-21 days, in a greater number of acromegalic patients.

Neurosurgery restores late GH rise after glucose-induced suppression in cured acromegalics.

OBJECTIVE AND DESIGN: A decrease of GH levels below 2 microg/l after an oral glucose tolerance test (OGTT) is still currently accepted as the gold standard for assessing cure in surgically treated acromegaly. Whether glucose-induced suppression of GH is accompanied by a restoration of normal GH late rebound has not yet been evaluated in this disease. In order to assess the restoration of normal GH regulation after removal of a pituitary adenoma, we have evaluated GH changes after an OGTT in a series of selected acromegalic patients (transsphenoidal surgery and lack of pituitary failure). METHODS: Twenty-nine patients (13 male, 16 female, age range 27-70 years) entered the study. Their neuroradiological imaging before neurosurgery showed microadenoma in 7, intrasellar macroadenoma in 8 and macroadenoma with extrasellar extension in 14. Plasma GH levels were assayed up to 300 min after glucose administration (75 g p.o.) and IGF-I on basal samples. RESULTS: Basal GH levels were below 5 microg/l in 20 patients and below 2 microg/l in 5 of these. Normal age-adjusted IGF-I levels were observed in 12 patients. GH values were suppressed below 2 microg/l during an OGTT in 13 patients, and below 1 microg/l in 7 of these. In 9 patients out of these 13, a marked rise in GH levels occurred after nadir. Baseline and nadir GH values of these 9 patients were not different from the corresponding values of the other 4 patients without OGTT-induced late GH peaks. CONCLUSIONS: GH rebound after GH nadir occurs in acromegalic patients considered as cured on the basis of OGTT-induced GH suppression and/or IGF-I normalization. The restoration of this physiological response could be regarded as a marker of recovered/preserved integrity of the hypothalamic-pituitary axis. Even though the reason for this GH rebound has not yet been elucidated (GHRH discharge?/end of somatostatin inhibition?), the lack of late GH peak in the patients regarded as cured by the usual criteria could be due to injury to the pituitary stalk caused by the adenoma or by surgical manipulation.

Cabergoline in acromegaly: a renewed role for dopamine agonist treatment?

OBJECTIVE AND DESIGN: Eighteen active acromegalics entered a prospective open study with cabergoline (CAB), a dopaminergic drug much more potent than bromocriptine (Br). METHODS: CAB was administered for 6 months at doses ranging between 0.5 mg twice weekly and 0.5 mg/day. Clinical-anamnestic characteristics of the patients were: (i) sensitivity to dopamine agonist drugs (10 patients); (ii) resistance to somatostatin analogs (SAs) (8 patients): (iii) intolerance to SA (3 patients). In 2 patients marked hyperprolactinemia was present. RESULTS: Basal GH was 6.6 microg/l (2.2-50) (median (range)), and on treatment it was 3.5 microg/l (1.2-34) (P=0.013). The corresponding IGF-I values were 720 microg/l (410-1438) and 375 microg/l (167-1260) respectively (P=0.00001). Individual GH levels decreased below 2 microg/l in 5 patients, and between 2 and 5 microg/l in another 5 patients. IGF-I levels were suppressed below 50% of baseline in 8 patients and normal age-adjusted IGF-I values were reached in 5 patients (27% of the series). The retrospective comparison with previous chronic treatment with Br in the 10 suitable patients showed a greater effectiveness of CAB (IGF-I decrease on CAB treatment, 46.8%, on Br treatment, 31%, P=0.02). Adenoma shrank in the 3 patients whose pituitary imaging was repeated during CAB. CONCLUSIONS: These results envisage that CAB may represent a worthy therapeutic tool in acromegalic patients, inducing a degree of IGF-I and GH suppression comparable to SAs, administered by the oral route and much less expensive.

Scintigraphic imaging of pituitary adenomas: an in vivo evaluation of somatostatin receptors.

UNLABELLED: We have performed pituitary scintigraphy with the somatostatin (SS) analog pentetreotidean by (111In-P) in patients with GH-secreting adenoma or with "clinically non functioning" adenoma (NFA) to evaluate the presence and the functionality of SS receptors (SS-R). 111In-P pituitary accumulation was expressed as Activity Ratio (AR): the ratio between the uptake of radioactivity by the adenoma and that of the normal brain tissue. In subjects without pituitary disease, AR ranged from 1.6 to 2.2 and a value lower than 2.2 was thus arbitrarily considered as normal. In 15 out of the 17 patients with GH-secreting adenoma, an accumulation of the radioligand was shown. Median AR was 3.8 (range 1-6.9; in 14 AR were greater that 2.2) and ARs were directly correlated (r = 0.54; p < 0.05) with the suppressibility of plasma GH levels by octreotide (OC) acute administration. In two patients who repeated scintigraphy during chronic OC treatment, AR values were reduced. In all the 22 patients with NFA an accumulation of 111In-P at the pituitary level was observed and median AR was 3.0 (range 1.5-20; in 14 greater that 2.2). In vitro autoradiography of surgical specimens in 6 NFA patients revealed SS-R in 4 cases with high scintigraphic AR and negative results in two cases with low AR. Scintiscan was repeated during chronic OC treatment in 5 patients with high score: AR decreased in one patient, increased in three, and did not change in the other patient. No changes in tumor size were shown in any of these patients. A total of 8 patients (3 GH secreting and 5 NFA) had "normal" AR values. CONCLUSIONS: In acromegaly scintigraphy with 111In-P visualizes functioning pituitary SS-R coupled to intracellular events that control hormonal hypersecretion and tumor growth. In contrast, in spite of the positivity of 111In-P imaging in most patients with NFA, their receptors might have a defect in the coupling-transduction process, as they are not inhibited by OC treatment and no tumor shrinkage is observed.

Effects of tamoxifen on GH and IGF-I levels in acromegaly.

Tamoxifen (TAM), a non steroid partially competitive antagonist to the estrogen receptors, has been reported to decrease plasma GH and IGF-I levels both in vitro and in vivo. These data prompted us to evaluate GH and IGF-I changes in acromegaly after acute and chronic TAM administration. Nineteen acromegalic patients (6 M, 13 F, aged 30-70 years) were studied in a prospective open study. Acute TAM test (20 mg po) did not induce any significant change in GH and IGF-I levels. Chronic TAM treatment (20 mg/day for a month and 40 mg/day for another month) induced a transient increase in GH levels (from 9 [3-139] micrograms/l [median, range] to 12 [3-188] micrograms/l, p = 0.0025) and a persistent decrease in IGF-I levels (from 785 [500-1200] micrograms/l to 553 [209-1420] micrograms/l, p = 0.0034). Individual IGF-I values decreased in 13 patients and reached the normal range in 4 of them. At TAM withdrawal hormonal levels increased up to pretreatment values. There was no correlation between GH and IGF-I changes and results were not influenced by age, sex or gonadal status. In this setting it is likely that the observed decrease in plasma IGF-I levels is dependent on TAM activity at the hepatic level.

Clinical results of long-term slow-release lanreotide treatment of acromegaly.

Medical therapy is frequently needed to normalize growth hormone/insulin-like growth factor I secretion in acromegaly. The aim of this study was to determine the long-term effects of the slow-release (SR) somatostatin analogue lanreotide in 57 acromegalic patients. SR lanreotide (30 mg) was given every 14 days for 12 months. In 33% of patients, the drug dosage was raised to 60 mg and/or the time interval was shortened to 10 days. Two months of clinical evaluation followed drug discontinuation in 47 out of 48 (84%) patients who completed the 12-month period. A drug-related decrease in GH/IGF-I levels was observed. Basal GH/IGF-I levels were significantly (P < 0.001) reduced at 12 months, IGF-I was normalized in 35% of patients and GH levels were < 5 micrograms L-1 in 54%. There was a clinical improvement in patients complaining of joint pain, rachialgias, headache, digital paraesthesias and hyperhidrosis. Soft-tissue changes were documented by significant (P < 0.001) decreases in finger size. In 52 (91%) patients without overt diabetes, a slight but significant increase in integrated glycaemia (P < 0.001) was noted, while integrated insulin levels were reduced (P < 0.001). Of 33 (58%) patients with normal basal ultrasound examination of the gall bladder, three (9%) had developed asymptomatic gall stones or biliary sludge after 12 months. Adverse events were generally mild. They frequently (52%) occurred after the first SR lanreotide administration; only 28% were recurrent and 20% appeared for the first time during therapy. SR lanreotide is an effective treatment in most unselected acromegalic patients. Tolerance towards the drug is high. Subjective benefits seem to override the simple biochemical control of the disease. Glucose homeostasis more than the incidence of gall stones seems to require monitoring on therapy. SR lanreotide is clearly advantageous in improving patient compliance with medical treatment for acromegaly.

Effects of terguride on anterior pituitary function in parkinsonian patients treated with L-dopa: a double-blind study versus placebo.

In a randomized double-blind study, 20 parkinsonian patients (suffering from the disease for 2-18 years), chronically treated with levodopa (500-750 mg/day for 0.5-12 years), received terguride (1 mg b.i.d.) or placebo for 4 weeks. Growth hormone (GH), prolactin (PRL), thyroid-stimulating hormone (TSH), and insulin-like growth factor (IGF-I) secretions were studied before and after the morning dose of levodopa (250 mg p.o.), both before and at the end of study period. At the beginning of the study, basal hormonal levels were within normal limits, and levodopa administration induced a significant suppression in PRL and TSH levels (both p < 0.01)) and a significant increase in GH (p < 0.01). The same results were observed at the end of the study period in the placebo group. Addition of terguride induced a significant suppression in basal PRL levels (p < 0.01), whereas levodopa-induced hormonal changes were unaffected. These data suggest that the hypothalamic dopaminergic function that controls anterior pituitary hormones is preserved in parkinsonian patients, regardless of both the duration of the disease and the long-term treatment with levodopa. The strong additional prolactin-lowering effect of terguride indicates long-lasting dopaminergic effects, as is already known from hyperprolactinemic conditions. The dopaminergic effects of levodopa on TSH, GH, and IGF-I secretion were unchanged by terguride treatment. The anti-dopaminergic effects of terguride observed in the motor system in animal studies, as well as in levodopa-induced dyskinesias in parkinsonian patients, could not be observed in the case of the dopaminergic control of anterior pituitary hormones under the conditions of this study.

Persistence of somatostatinergic tone in acromegaly.

It is a matter of debate whether hypothalamic somatostatin (SRIH) secretion in acromegaly is preserved and still regulated by the physiological feedback mechanisms of growth hormone (GH) and insulin-like growth factor I. To gather further information on this, the reproducibility of plasma GH changes induced by growth hormone-releasing hormone (GHRH) administration was evaluated in 15 acromegalic patients. There was a highly significant correlation between the peak/basal ratio (P/B) GH response in the 15 patients administered GHRH on two separate occasions (r = 0.99, p < 0.001). The test was performed also before and after the administration of drugs able to inhibit or stimulate hypothalamic SRIH release, by activating (pyridostigmine) or inhibiting (pirenzepine) cholinergic pathways, respectively. The GHRH-induced GH response (P/B = 2, range 1.1-26.1) was increased significantly by pyridostigmine pretreatment in 30 patients (P/B = 2.6, range 1.3-34.8; p = 0.0045). In nine out of 30 patients an increase of greater than 2 SD of within-subject GHRH variability was observed in response to GHRH plus pyridostigmine when compared to GHRH alone. An inverse correlation (r = -0.37, p < 0.05) was observed between GH response to GHRH alone and after pyridostigmine pretreatment. On the contrary, no change of GHRH-induced GH response was observed in 12 patients after pirenzepine pretreatment (P/B = 1.9, range 1.1-5 and P/B = 2, range 1.3-6 without and after pirenzepine pretreatment, respectively). These data suggest that in acromegaly the somatostatinergic tone does not seem to fluctuate, and that it can be inhibited often by cholinergic pathway activation but not increased further by cholinergic suppression.

CV 205-502 in acromegaly.

In a series of acromegalic patients the effects of CV 205-502, a new long-acting dopamine-agonist drug, on growth hormone (GH), insulin-like growth factor I (IGF-I) and prolactin (PRL) levels were evaluated in an open study. After acute administration of CV 205-502 (0.0375 mg, po) in 12 patients. GH levels did not change, whereas PRL values significantly decreased and remained suppressed for 24 h. In the 14 patients who underwent chronic CV 205-502 treatment (at daily doses of 0.150-0.600 mg/day given at bedtime or b.i.d. for up to 12 months). GH and IGF-I levels fell significantly from 60 +/- 17 (mean +/- SEM) micrograms/l to 28 +/- 10 micrograms/l and from 1127 +/- 84 micrograms/l to 738 +/- 57 micrograms/l, respectively (p < 0.05). A retrospective comparison with the results obtained for the same patients during a previous chronic bromocriptine treatment (at daily doses of 5-20 mg given t.i.d. or q.i.d.) did not show any significant difference in the suppression of GH levels between the two treatments; no bromocriptine-resistant patient was CV 205-502 sensitive, even at the highest CV 205-502 dose used. We conclude that in acromegaly chronic treatment with this new dopaminergic drug has a GH- and PRL-lowering effect that is similar to but more prolonged than that of bromocriptine, and normal or near-normal GH and IGF-I levels may be obtained in a few patients with b.i.d. administration. However, no GH-lowering effect is observed in bromocriptine-resistant patients.

Doxorubicin for acromegaly: a case report.

We report the case of an acromegalic woman, aged 35 years, with a huge GH-secreting tumor, repeatedly treated with neurosurgery and radiotherapy, not responsive to bromocriptine (Br) and octreotide (SMS), whose clinical picture evolved to coma due to endocranic hypertension. Since remnant size was too large to be further treated by surgery, chemotherapy with doxorubicin (DOX) (100 mg i.v. every three weeks up to 0.5 mg/m2 over 7 months) was started. Treatment was followed by a rapid improvement of clinical picture with resumption out of coma, progressive decline of GH levels (from 800 ng/ml to 15 ng/ml) and a slight shrinkage of tumor. No side effects were observed during DOX administration. We suggest that in those few acromegalic patients resistant both to SMS and Br, and with poor prognosis, DOX may be effectively used.

Resistance to a long-acting somatostatin analog (SMS 201-995) reversed by surgery in acromegaly.

A 42-year-old woman had acromegaly and a large macroadenoma with supra- and parasellar extension. Her GH levels (median 85 ng/ml, range 63-170 ng/ml) were not responsive to TRH (200 micrograms iv), GHRH (100 micrograms iv) and bromocriptine (Br 2.5 mg po) acute tests; Sm-C level was 8 U/ml. She was treated with octreotide (SMS) (up to 1500 micrograms daily) for 3 months. No changes of clinical, biochemical and radiological findings were seen, therefore she underwent transsphenoidal surgery. After surgery, hypopituitarism and diabetes insipidus appeared: GH levels remained high (median 45 ng/ml; range 37-56 ng/ml), but became responsive to Br acute test. The patient was given SMS again, and this resulted in clinical improvement, marked reduction of GH and Sm-C levels and slight shrinkage of the residual tumor. Speculative hypotheses about this previously unreported phenomenon might be either an excess of both GHRH and somatostatin, caused by a primary increase of dopaminergic tone, or a primary excess only of GHRH; in both cases the surgical lesion of the hypothalamic-pituitary region might have impaired the neurohormones inflow to the residual pituitary and so let SMS and Br exert their inhibitory actions on GH secretion.

Prolactin response to growth hormone-releasing hormone during chronic thyrotropin-releasing hormone infusion in the treatment of amyotrophic lateral sclerosis.

In six patients suffering from amyotrophic lateral sclerosis we evaluated changes of T4, T3, TSH, PRL, and GH during treatment by continuous iv infusion of TRH for at least 15 days. No clinical improvement was detected. A significant rise of thyroid hormone levels was observed, as well as an upward trend of basal TSH levels and no change of basal PRL and GH levels. TRH acute test-induced TSH and PRL responses became blunted. Treatment provoked also the onset of a responsiveness of PRL to GHRH. The reduced TSH and PRL responses to acute TRH test during treatment could be explained by a down-regulation of TRH pituitary receptors. On the contrary, the onset of PRL responsiveness to GHRH is at present without a satisfactory explanation.

[Medical treatment of acromegaly with dopaminergic agents]. / Il trattamento medico dell'acromegalia con farmaci dopaminergici.

The medical treatment of acromegaly with dopaminergic drugs has its physiopathological premise in the observation that agents capable of stimulating dopaminergic receptors directly are capable of determining GH secretion inhibition in a large percentage of acromegalic patients. Chronic administration of 5-20 mg/die of bromocryptin, long acting dopaminergic agonist, leads to a stable reduction in the levels of GH and somatomedin C (SmC) in about 50% of patients. However, these are only normalised in 20%. Treatment induces marked improvement in the clinical and metabolic changes typical of acromegalic disease. The therapeutic effect of dopaminergics may be maintained for periods of treatment lasting years but upon suspension of treatment pH levels return quickly to pretreatment levels. The antitumoral effect of the dopaminergic frequently encountered in prolactinomas is a rarer event in acromegaly and occurs more readily in patients with mixed secreting GH and PRL tumours than in pure GH. Currently octractide, a long lasting somatostatin analogue, is the most effective drug in the medical treatment of acromegaly; however the dopaminergic agonists remain a valid alternative.

Medical treatment of acromegaly with SMS 201-995, a somatostatin analog: a comparison with bromocriptine.

We studied the effects of acute and chronic sc administration of SMS 201-995 (SMS), a long-acting somatostatin analog, in acromegalic patients. The results were compared with those obtained in the same patients treated with oral bromocriptine (Brc). A single dose of 50 micrograms SMS administered to 28 patients induced a more rapid, greater, and more prolonged reduction in plasma GH levels than did 2.5 mg Brc. Chronic treatment [60-330 days; mean 208 +/- 23 (+/- SEM)] with SMS (100-300 micrograms/day) induced in 16 patients a significantly greater decrease in mean plasma GH and somatomedin-C levels than did 20 mg Brc. Combined treatment with the 2 agents had an additional effect. The clinical and metabolic parameters of acromegaly dramatically improved in all patients whose plasma GH and somatomedin-C levels decreased even if they were not normalized by SMS. Reduction in tumor size occurred in 3 of the 10 patients examined by computed tomography before and during SMS treatment. We conclude that SMS is more effective than Brc and that the 2 drugs may be complementary in the medical treatment of acromegaly.

Relationship between somatomedin-C and growth hormone levels in acromegaly: basal and dynamic evaluation.

The relationship between basal and stimulated plasma GH and somatomedin-C (SmC) levels in acromegalic patients was evaluated. The basal plasma SmC levels of 66 patients were significantly correlated (P less than 0.01) with mean daily plasma GH levels, but not with the percent GH increase after GH-releasing hormone or TRH or the GH decrease after acute bromocriptine administration. Bromocriptine (7.5-15 mg/day) administration for 9.2 +/- 0.9 (+/- SD) months in 20 patients significantly (P less than 0.05) decreased GH levels. SmC decreased significantly [from 9.8 +/- 1.9 to 5.1 +/- 0.7 U/ml (mean +/- SE)] only in the 10 patients who had the more marked GH inhibition. The administration of a somatostatin analog, SMS 201-995 (100 micrograms twice daily), to 12 patients for 16 weeks significantly decreased plasma GH and SmC levels beginning on the second day of therapy; normal SmC levels were achieved in 5 of 12 patients. Pituitary adenomectomy resulted in normal GH and SmC levels in 10 of 12 and 8 of 12 patients, respectively. Our data indicate an overall dependency of plasma SmC levels on plasma GH levels in acromegaly, although similar GH levels may have differing somatomedin-stimulating activities. A derangement in the feedback mechanisms controlling GH secretion is indicated by the failure of elevated SmC levels to influence the GH responsiveness to releasing hormones. In evaluating pharmacological or surgical treatments of acromegaly, a single plasma SmC value can reliably replace several plasma GH determinations.

Serum type III procollagen propeptide levels in acromegalic patients.

Serum type III procollagen propeptide (PIIIP) is a reliable index of tissue collagen synthesis. Since in acromegaly there is increased collagen production, we measured serum PIIIP in acromegalic patients before any treatment (basal), during medical treatment with the somatostatin analog SMS 201-995, and after pituitary adenomectomy. In all patients, serum GH and plasma somatomedin-C (SmC) levels were also measured. Basal serum PIIIP levels were significantly (P less than 0.01) higher in acromegalic patients (mean +/- SEM, 22.7 +/- 2.1 ng/ml) than in normal subjects (n = 30; 9.7 +/- 0.5 ng/ml), and they were significantly correlated with plasma SmC values (r = 0.31; P less than 0.05). A significant (P less than 0.01) reduction in PIIIP levels occurred in patients treated with SMS 201-995 or surgery (from 24.3 +/- 2.7 to 12.4 +/- 1 ng/ml) as well as in GH and SmC levels. The maximum percent decrease in serum PIIIP was significantly correlated with those in GH (r = 0.65; P less than 0.01) and SmC (r = 0.60; P less than 0.01). Serum PIIIP levels did not change in those patients in whom neither GH nor SmC were decreased by treatment. In conclusion, serum PIIIP levels are elevated in acromegalic patients, and they decline in parallel with GH and SmC during medical or surgical treatment. Serum PIIIP measurements may be useful in the evaluation of acromegalic patients to gain information on the biological activity of GH and in monitoring the course of the disease.