Evaluation of growth hormone stimulation tests in cured acromegalic patients

Surgery induced hypopituitarism in acromegalic patients: a systematic review and meta-analysis of the results

PURPOSE

Hypopituitarism is a possible complication of the surgical treatment of acromegaly. However, there is a wide variability in the incidence rates of surgery-induced hypopituitarism. The purpose of this study was the systematic collection and synthesis of information on the incidence rates of hypopituitarism, panhypopituitarism, specific axis deficiencies and diabetes insipidus after surgery for acromegaly treatment.

METHODS

We systematically reviewed all the papers that have reported pituitary deficits after surgery for acromegaly published up until December 2014, in the PubMed database. We identified 92 studies enrolling 6988 patients. A meta-analysis was performed to evaluate the incidence rates. We also performed several subgroup analyses to evaluate the impact of both surgical technique, and treatment prior to surgery, on the results.

RESULTS

The weighted incidence rates were 12.79 % for hypopituitarism (95 % CI 9.88-16.00 %), 2.50 % for panhypopituitarism (95 % CI 1.24-4.15 %), 6.50 % for ACTH deficiency (95 % CI 4.07-9.44 %), 4.39 % for TSH deficiency (95 % CI 2.99-6.04 %), 6.70 % for FSH/LH deficiency (95 % CI 3.89-10.17 %), 14.95 % for GH deficiency (95 % CI 7.25-24.64 %), 10.05 % for transient (95 % CI 7.18-13.33 %) and 2.42 % for permanent diabetes insipidus (95 % CI 1.70-3.27 %).

CONCLUSION

Our study provides new data on the incidence rates of hypopituitarism, specific pituitary axis deficiencies and diabetes insipidus after surgical treatment of acromegaly. Somatotroph function appears to be more prone to deficit than the other axes. However, there is a high heterogeneity between studies and several factors may influence the incidence of hypopituitarism.

Growth hormone deficiency after mild combat-related traumatic brain injury

OBJECTIVE

Traumatic brain injury (TBI) has been recognized as a cause of growth hormone deficiency (GHD) in civilians. However, comparable data are sparse in veterans who incurred TBI during combat. Our objective was to determine the prevalence of GHD in veterans with a history of combat-related TBI, and its association with cognitive and psychosocial dysfunction.

DESIGN

Single center prospective study.

PATIENTS

Twenty male veterans with mild TBI incurred during combat 8-72 months prior to enrollment.

MEASUREMENTS

GHD was defined by a GH peak <3 μg/L during glucagon stimulation test. Differences in neuropsychological, emotional, and quality of life of the GHD Veterans were described using Cohen's d. Large effect sizes were considered meaningful.

RESULTS

Mean age was 33.7 years (SD 7.8) and all subjects had normal thyroid hormone and cortisol levels. Five (25%) exhibited a subnormal response to glucagon. Sixteen participants (80%) provided sufficient effort for valid neuropsychological assessment (12 GH-sufficient, 4 GHD). There were large effect size differences in self-monitoring during memory testing (d = 1.46) and inhibitory control (d = 0.92), with worse performances in the GHD group. While fatigue and post-traumatic stress disorder were comparable, the GHD group reported more depression (d = 0.80) and lower quality of life (d = 0.64).

CONCLUSIONS

Our study found a 25% prevalence of GHD in veterans with mild TBI as shown by glucagon stimulation. The neuropsychological findings raise the possibility that GHD has adverse effects on executive abilities and mood. Further studies are needed to determine whether GH replacement is an effective treatment in these patients.

Clinical predictors of GH deficiency in surgically cured acromegalic patients

OBJECTIVE

Even in patients with cured acromegaly, GH deficiency (GHD) after transsphenoidal adenomectomy (TSA) adversely affects body composition and inflammatory biomarkers of cardiovascular risk. In this study, clinical parameters for predicting GHD after TSA in 123 cured acromegalic patients were investigated.

DESIGN AND METHODS

GH levels were measured at 6, 12, 18, 24, 48, and 72 h after TSA and serial insulin tolerance tests were conducted at 6 months, 2 years, and then every 2 years after TSA.

RESULTS

GHD was found in 12 patients (9.8%) at 4.1 (range: 0.5-4.1) years after TSA. IGF1 levels were significantly lower at 6 months after TSA in GHD group than intact GH group (175.9 vs 316.8 μg/l, range: 32.0-425.0 and 96.9-547.3 respectively, P=0.008). Adenomas involving both sides of the pituitary gland were significantly more frequent in GHD patients (29.7 vs 83.3%; P=0.002). Furthermore, immediate postoperative 72-h GH levels after TSA were significantly lower (0.17 vs 0.45, range: 0.02-0.93 and 0.02-5.95 respectively, P=0.019) in GHD patients. In multiple logistic regression analysis, bilaterality of tumor involvement (odds ratio (OR)=10.678, P=0.003; 95% CI=2.248-50.728) and immediate postoperative 72-h GH level (OR=0.079, P=0.047; 95% CI=0.006-0.967) showed significant power for predicting GHD.

CONCLUSIONS

These data suggest that bilateral involvement of a pituitary adenoma and severely decreased immediate postoperative serum GH levels at 72 h after TSA may be independent risks factor for accelerated GHD in acromegalic patients.

Prevalence of pituitary hormone dysfunction, metabolic syndrome, and impaired quality of life in retired professional football players: a prospective study

Hypopituitarism is common after moderate and severe traumatic brain injury (TBI). Herein, we address the association between mild TBI (mTBI) and pituitary and metabolic function in retired football players. Retirees 30-65 years of age, with one or more years of National Football League (NFL) play and poor quality of life (QoL) based on Short Form 36 (SF-36) Mental Component Score (MCS) were prospectively enrolled. Pituitary hormonal and metabolic syndrome (MetS) testing was performed. Using a glucagon stimulation test, growth hormone deficiency (GHD) was defined with a standard cut point of 3 ng/mL and with a more stringent body mass index (BMI)-adjusted cut point. Subjects with and without hormonal deficiency (HD) were compared in terms of QoL, International Index of Erectile Function (IIEF) scores, metabolic parameters, and football career data. Of 74 subjects, 6 were excluded because of significant non-football-related TBIs. Of the remaining 68 subjects (mean age, 47.3±10.2 years; median NFL years, 5; median NFL concussions, 3; mean BMI, 33.8±6.0), 28 (41.2%) were GHD using a peak GH cutoff of <3 ng/mL. However, with a BMI-adjusted definition of GHD, 13 of 68 (19.1%) were GHD. Using this BMI-adjusted definition, overall HD was found in 16 (23.5%) subjects: 10 (14.7%) with isolated GHD; 3 (4.4%) with isolated hypogonadism; and 3 (4.4%) with both GHD and hypogonadism. Subjects with HD had lower mean scores on the IIEF survey (p=0.016) and trended toward lower scores on the SF-36 MCS (p=0.113). MetS was present in 50% of subjects, including 5 of 6 (83%) with hypogonadism, and 29 of 62 (46.8%) without hypogonadism (p=0.087). Age, BMI, median years in NFL, games played, number of concussions, and acknowledged use of performance-enhancing steroids were similar between HD and non-HD groups. In summary, in this cohort of retired NFL players with poor QoL, 23.5% had HD, including 19% with GHD (using a BMI-adjusted definition), 9% with hypogonadism, and 50% had MetS. Although the cause of HD is unclear, these results suggest that GHD and hypogonadism may contribute to poor QoL, erectile dysfunction, and MetS in this population. Further study of pituitary function is warranted in athletes sustaining repetitive mTBI.

Severe growth hormone deficiency is rare in surgically-cured acromegalics

Growth hormone deficiency (GHD) in surgically-cured acromegalics has been reported to negatively affect their metabolic condition and quality of life (QOL). The incidence of GHD, its causes, and its effects on their physio-psychological condition remain to be examined in detail. We performed a retrospective study to investigate GH secretory function in surgically-cured acromegalics, prognostic factors of GHD, and its impact on QOL. The study population consisted of 72 acromegalics who were determined to be surgically cured according to the Cortina consensus criteria. We recorded the incidence of impaired GH secretory function based on the peak GH level during postoperative insulin tolerance test (ITT) which lowered their nadir blood sugar to under 50 mg/dL. Their QOL was evaluated by SF-36. In surgically-cured acromegalics, the incidence of severe GHD (peak GH during ITT ≦ 3.0 μg/L) was 12.5 % (9/72). The preoperative tumor size was significantly larger in patients with severe GHD than without severe GHD (21.9 ± 9.0 vs. 15.5 ± 7.1 mm, p = 0.017). The peak GH levels during postoperative ITT were statistically correlated with the physical but not the mental component summary of the SF-36 score. The incidence of GHD was 12.5 % in our surgically-cured acromegalics. As some QOL aspects are positively related with peak GH levels during postoperative ITT, efforts should be made to preserve pituitary function in acromegalic patients undergoing adenomectomy.

GH replacement improves quality of life and metabolic parameters in cured acromegalic patients with growth hormone deficiency

OBJECTIVE

Effects of GH replacement in patients with GH deficiency (GHD) after a cure for acromegaly so far have been poorly studied, although its prevalence among acromegalic patients may reach the 60%. The aim of the study was to evaluate whether metabolic parameters and quality of life are improved by GH replacement in patients with prior acromegaly and severe GHD.

DESIGN AND METHODS

This was a prospective study on 42 GHD subjects [22 men, mean age (sd): 48 ± 10]: 10 acromegalics treated with recombinant human GH (group A), 12 acromegalics who refused treatment (group B), and 20 subjects operated for nonfunctioning pituitary adenoma on recombinant human GH (group C). Serum IGF-I levels, lipid profile, glucose levels (fasting and after an oral glucose tolerance test), glycosylated hemoglobin, insulin resistance (homeostasis model assessment insulin resistance index), anthropometric parameters (body mass index, waist circumference, body composition), and quality of life (Questions on Life Satisfaction-Hypopituitarism Z-scores) were evaluated at baseline and after 12 and 36 months.

RESULTS

At baseline, group B showed higher IGF sd score than group A and C, as well as better quality of life and higher post-oral glucose tolerance test glucose levels than group A. After 12-months, similarly in group A and C, the IGF-I sd score significantly increased, and body composition and lipid profile improved, without deterioration of glucose tolerance. Quality of life significantly improved too, and the baseline difference between group A and B disappeared. Results were confirmed after 36 months.

CONCLUSIONS

In GHD acromegalic patients, GH therapy improved body composition, lipid profile, and quality of life as in patients with GHD due to nonfunctioning pituitary adenoma, without negative effects on glucose metabolism. GH replacement therapy should be considered in these patients, as in patients with GHD from other causes.

GH deficiency in patients after cure of acromegaly by surgery alone

OBJECTIVE

The aim of this study was to determine the frequency and characteristics of severe GH deficiency (sGHD) in patients after treatment of acromegaly by surgery alone.

DESIGN AND METHODS

One hundred and eighty-six patients fulfilling the criteria for cure of acromegaly were examined by GH-releasing peptide-2 stimulation test or arginine stimulation test as well as oral glucose tolerance test (GTT). In addition, the Japanese adult hypopituitarism questionnaire was completed to determine the quality of life (QoL).

RESULTS

sGHD was found in 17 patients (9.1%; the GH-deficient group), and not found in 169 patients (90.9%; the GH-sufficient group). There were no significant differences in preoperative serum GH levels, IGF1 levels, incidence of hyperprolactinemia, tumor volumes, or incidence of microadenoma between the two groups. Upon follow-up examination, IGF1 levels and Z-scores of IGF1 levels were significantly lower in the GH-deficient group than in the GH-sufficient group, whereas neither basal GH levels nor nadir GH levels during 75 g GTT were significantly different between the two groups. Moreover, sGHD patients had a substantially higher incidence of multiple pituitary failures (17.6 vs 2.4%) and dyslipidemia (60 vs 16.2%). sGHD patients had a substantially poorer condition-related QoL.

CONCLUSIONS

This is the first large-scale, single-center, clinical study to evaluate sGHD in patients after cure of acromegaly by surgery alone. This study found that sGHD occurred in ~9% of patients and assessment of GHD by stimulation tests is critical after successful treatment of acromegaly by surgery.

Adequacy of current postglucose GH nadir limit (< 1 microg/l) to define long-lasting remission of acromegalic disease

OBJECTIVE

Some authors proposed to lower the present postglucose GH nadir cut-off (i.e. < 1 microg/l) to that obtained in healthy subjects to establish remission of acromegaly. The aim of the study was to correlate GH nadir with hormonal and metabolic parameters and to confirm the adequacy of the current limit to define disease remission.

DESIGN AND PATIENTS

Retrospective study of 40 acromegalic patients cured by surgery, followed by radiotherapy when appropriate, studied at the time of disease remission (Phase 1) and re-evaluated after at least 3 years' follow-up (median 6.5 year, Phase 2). GH nadir was evaluated in 44 sex- and age-matched controls.

MEASUREMENTS

Symptom score, pituitary function, neuroradiological imaging, metabolic parameters (BMI, glucose metabolism, insulin sensitivity, lipid profile, blood pressure).

RESULTS

The upper limit of the 'normal' GH nadir was fixed at 0.26 microg/l (mean + 2SD of controls). In Phase 1, GH nadir was < 0.26 microg/l in 16 patients (Group A) and > 0.26 microg/l in 24 patients (Group B). Group B had only slightly higher IGF-1 SDS (0.4 +/- 1.0 vs.- 0.1 +/- 1.0, P = ns) and lower body mass index (BMI) than Group A (26.2 +/- 2.4 vs. 30.6 +/- 4.5 kg/m(2), P < 0.005). GH nadir positively correlated with IGF-1 (P < 0.05, r = 0.32) and negatively with BMI (P < 0.05, r = 0.42). In Phase 2, all patients had IGF-1 levels in the normal range and GH nadir < 1 microg/l, both parameters being even lower than those found at the time of remission. No patient had either clinical or neuroradiological evidence of disease recurrence.

CONCLUSIONS

The current GH nadir limit is still adequate to define both short- and long-lasting remission of acromegaly, independently of the type of definitive treatment. Patients with the lowest GH nadir should probably be monitored long-term for adequacy of their GH secretion.