Can intra-operative GH measurement in acromegalic subjects predict completeness of surgery?

Intraoperative Prediction of Long-Term Remission in Acromegaly

BACKGROUND

The features of long-term remission in acromegaly adenomectomy are incompletely understood. An intraoperative predictor for long-term outcome would be valuable for assessing resection of growth hormone (GH)-secreting tumors in real-time.

OBJECTIVE

To evaluate whether intraoperative GH measurement could predict long-term outcomes for acromegaly.

METHODS

In 47 patients, peripheral blood GH levels were measured thrice intraoperatively: once before tumor dissection, once during tumor dissection, and once after tumor dissection. Long-term remission was defined by age-appropriate, normalized insulin-like growth factor-1 at most recent follow-up and a random GH less than 1.0 ng/mL. Patients were only considered to be in long-term remission without the use of postoperative medical therapy for acromegaly or radiation therapy.

RESULTS

The median length of follow-up was 4.51 (range: 0.78-9.80) years. Long-term remission was achieved in 61.7% (29/47) of operations. Like previous studies, cavernous sinus invasion (odds ratio [OR]: 0.060; 95% CI: 0.014-0.260; P value < .01), suprasellar extension (OR: 0.191; 95% CI: 0.053-0.681; P value<.01), and tumor size greater than 1 cm (OR: 0.177; 95% CI: 0.003-0.917; P value = .03) were associated with not being in long-term remission. The minimum GH measured intraoperatively predicted long-term outcome (area under the curve: 0.7107; 95% CI: 0.537-0.884; P value < .01). The odds ratio of remission in patients with the lowest quartile minimum intraoperative GH compared with patients with the highest quartile minimum intraoperative GH was 27.0 (95% CI: 2.343-311.171; P value < .01).

CONCLUSION

Minimum intraoperative GH may predict long-term outcome for acromegaly, which in principle could provide the pituitary neurosurgeon with real-time feedback and inform intraoperative decision making.

Point-of-Care Endocrine Diagnostics

Endocrinology relies on hormone and metabolite measurement for public health screening, diagnostics, and disease management. Advances in microfluidics, immunoassay technology, electronics, and software are moving in vitro endocrine diagnostics from the laboratory to the point of care. Point-of-care endocrine diagnostics provide results clinically equivalent to those produced by expensive laboratory instrumentation for a fraction of the cost and with a substantially more rapid turnaround time. Similar to the transformation of mainframe computers into laptops, tablets, and smartphones, clinical laboratories are evolving into point-of-care technologies.

Diagnosis, treatment and clinical perspectives of acromegaly

Acromegaly is an insidious disease of the pituitary caused by a growth hormone-secreting adenoma. Generally, the diagnosis is made rather late in the course of the disease. Currently, acromegaly can be cured in about half of the patients with the disease by expert surgery. The remainder of non-surgically cured patients often can be effectively treated with somatostatin analogs; either with the new generation of dopaminergic drugs or with Pegvisomant, a GH-receptor blocking agent. However, at the time of diagnosis many patients suffer from serious comorbidities, including hypertension, heart disease, arthrosis, sleep apnea and diabetes mellitus. Recent reports have shown that mortality risk can be normalized. Nevertheless, all efforts should be undertaken to treat comorbidities. New strategies for surgery and medical treatment are discussed.

Kinetics and secretion of placental growth hormone around parturition

OBJECTIVE

During pregnancy, placental growth hormone (PGH) is secreted into the maternal circulation, replacing pituitary GH. It is controversial whether PGH levels decline during vaginal birth. After placental expulsion, PGH is eliminated from the maternal blood. GH binding protein (GHBP) and body mass index (BMI) influence GH kinetics, but their impact on PGH kinetics is unknown. The present study was undertaken to define the kinetics of PGH during vaginal delivery and Caesarian section and to relate these kinetics to GHBP and BMI.

DESIGN

A short term, prospective cohort study.

METHODS

Twelve women had repeated blood samples drawn during vaginal delivery. From 26 women undergoing planned Caesarian delivery (CS) repeated blood samples were withdrawn before, during and after the CS, allowing PGH half-life determination.

RESULTS

During vaginal delivery, median PGH values did not change before expulsion of the placenta, although individual fluctuations were seen. Clearance of PGH from the maternal circulation was best described by a two-compartment model. The initial half-life of serum PGH was (mean +/- s.d.) 5.8 +/- 2.4 min, and the late half-life was (median) 87.0 min (range: 25.1-679.6 min). The late half-life was correlated to the pre-gestational BMI (r = 0.39, P = 0.047), but not to the serum GHBP concentration.

CONCLUSIONS

Serum PGH did not decrease significantly during vaginal delivery. Elimination of PGH fitted a two-compartment model, with an estimated initial half-life of 5.8 min. The late phase serum half-life of PGH was related to BMI, suggesting a role for maternal fat mass in PGH metabolism.

Early postoperative indicators of late outcome in acromegalic patients

OBJECTIVE

According to current criteria, normalised serum IGF-1 and glucose-suppressed GH < 1 ng/ml are indicators of biochemical cure in acromegalic patients. We performed a retrospective study to assess whether the attainment of these values in the early postoperative period was predictive of future IGF-1 normalisation and disease inactivity.

PATIENTS, MEASUREMENTS AND RESULTS

Between 1978 and 1999, 78 acromegalic patients underwent resection for pituitary adenomas. At the end of the mean follow-up period of 7 years, 43 (55.1%) showed normalised IGF-1 levels and no disease activity. In 51 cases, both IGF-1 and glucose-suppressed GH were examined within the first postoperative month. Of this group, all 19 patients who had early glucose-suppressed GH < 1 ng/ml and were treated by surgery alone maintained normal IGF-1 levels throughout the follow-up; four of them demonstrated delayed (i.e. more than 30 days after the operation) IGF-1 normalisation. In 19 patients with early glucose-suppressed GH levels of 1-4 ng/ml, seven of 11 patients with early normalised IGF-1 and two of eight patients with early IGF-1 elevation manifested eventual IGF-1 normalisation. However, none of the 13 patients with early glucose-suppressed GH > 4 ng/ml attained IGF-1 normalisation. Both univariate and multivariate analyses indicated that early glucose-suppressed GH was a significant factor for predicting late normalised IGF-1; the cut-off value was 1.5 ng/ml (sensitivity: 0.97; specificity: 0.75; odds ratio: 90).

CONCLUSION

The attainment of both normalised IGF-1 and glucose-suppressed GH < 1 ng/ml, even during the early postoperative period, suggests absolute cure in acromegalic patients. However, even in patients who do not meet both criteria within the first postoperative month, glucose-suppressed GH < 1.5 ng/ml, or glucose-suppressed GH < 4 ng/ml coupled with early IGF-1 normalisation indicate the possibility of eventual normalisation of IGF-1 and disease inactivity without adjuvant therapy. These postoperative parameters may be useful for assessing the desirability of further treatment.

Effectiveness of secondary transnasal surgery in GH-secreting pituitary macroadenomas

Transsphenoidal surgery is the first therapeutic option in acromegaly, but the management of persistent or recurrent cases of the disease after surgery has been controversial. This study presented the results of secondary transnasal surgery for residual or recurring growth hormone (GH)-secreting macroadenoma with reference to intraoperative GH measurement. It focused on 22 patients who underwent secondary transsphenoidal surgery for 18 residual and 4 recurring GH-secreting pituitary macroadenomas from 1990 to 1999. To assess complete tumor removal, plasma GH concentration was measured intraoperatively. Before secondary surgery, plasma GH levels without medical treatment ranged from 2.0 to 239.0 microg/l (mean 31.5 +/- 50.4). Magnetic resonance imaging demonstrated 16 transnasally resectable tumors and 6 nonresectable grossly invasive tumors. Intraoperative plasma GH concentrations declined sufficiently in 9 of 16 with transnasally resectable tumors, but in the remaining 7 cases the tumors were further explored and normalization of GH levels was ultimately obtained in 4 out of these cases. It was impossible to completely remove the tumors in all the 6 patients with transnasally nonresectable tumors. Thirteen of 22 patients achieved endocrinological remission by rigorous criteria. In transnasally resectable tumors, the endocrinological remission rate was 81.3% (13 of 16 patients) with no recurrence during the follow-up period of at least 4 years. Secondary transnasal surgery for residual or recurring GH-secreting pituitary macroadenomas is a safe and effective treatment, if done along with intraoperative GH measurement. Endocrinological remission can be obtained with high probability in patients who suffer from macroadenomas with suprasellar extension, with the exception of transnasally nonresectable grossly invasive tumors.

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.