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Revisiting growth hormone nadir cut-offs for remission in patients with acromegaly
Jiwon Kim1,2,3, Yoon-A Hwang2,4, Yae Won Park5
1Department of Internal Medicine, National Health Insurance Service Ilsan Hospital, Goyang, Republic of Korea.
Objective:
Over the past decade, the growth hormone (GH) nadir cut-off during the oral glucose tolerance test for remission in patients with acromegaly was changed from 0.4 to 1.0 μg/L due to the limited use of ultrasensitive detection kits to measure GH levels. However, the optimal cut-off level for GH nadir remains unclear. This retrospective study aimed to investigate the association between different GH nadir cut-offs and prognosis in patients with acromegaly.
Design And Methods:
A total of 285 patients with acromegaly with a glucose-suppressed GH nadir <1 μg/L at 3-6 months after trans-sphenoidal adenomectomy were divided into two groups according to the glucose-suppressed GH nadir levels at 3-6 months post-operatively (group A: <0.4 μg/L; group B: 0.4-1.0 μg/L). GH levels were measured using an ultrasensitive IRMA. The clinical, hormonal, metabolic, and neuroradiological data of the two groups were compared.
Results:
Female sex, as well as confirmed macroadenomas, was significantly overrepresented in group B. The 5-year rate of patients who achieved nadir GH < 1.0 μg/L and age- and sex-matched normal IGF-1 was significantly higher in group A than that in group B. However, there was no significant difference between the two groups in metabolic parameters at 12 months post-operatively.
Conclusion:
Different GH nadir cut-offs were associated with different 5-year rates of patients who achieved nadir GH <1.0 μg/L and age- and sex-matched normal IGF-1, suggesting that a strict GH nadir threshold of 0.4 μg/L correlates better with remission.
Insights
A stricter growth hormone (GH) nadir threshold of 0.4 μg/L better predicts remission in acromegaly patients. This finding suggests a lower GH nadir level is more indicative of successful treatment outcomes.
Area of Science:
- Endocrinology
- Oncology
Background:
- The established cut-off for growth hormone (GH) nadir in acromegaly remission has shifted from 0.4 to 1.0 μg/L.
- This change is attributed to the limited availability of ultrasensitive GH detection kits.
- The optimal GH nadir level for assessing acromegaly remission remains uncertain.
Purpose of the Study:
- To investigate the association between varying GH nadir cut-offs and patient prognosis in acromegaly.
- To determine if a stricter GH nadir threshold correlates with better remission rates.
Main Methods:
- A retrospective study of 285 acromegaly patients post-trans-sphenoidal adenomectomy.
- Patients were categorized into two groups based on GH nadir levels at 3-6 months: <0.4 μg/L (Group A) and 0.4-1.0 μg/L (Group B).
- GH levels were measured using an ultrasensitive immunoradiometric assay (IRMA).
Main Results:
- Group B showed a higher prevalence of female patients and confirmed macroadenomas.
- The 5-year remission rate (nadir GH < 1.0 μg/L and normal IGF-1) was significantly higher in Group A (<0.4 μg/L).
- No significant differences in metabolic parameters were observed at 12 months post-operatively between the groups.
Conclusions:
- Different GH nadir cut-offs are linked to varying long-term remission rates.
- A strict GH nadir threshold of 0.4 μg/L appears to correlate more strongly with achieving and maintaining remission in acromegaly.
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