Acromegaly
Patommatat MD
Content
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Physiology of growth hormone (GH)
Etiology of Acromegaly
Clinical manifestation & prognosis
Diagnosis
Treatment & monitoring
Sleep  GH secretion
Factors affecting GH secretion
Increased
• GHRH
• Fasting
• Ghrelin
• Estrogen
• High protein diet
Decreased
• Somatostatin
• Aging & obesity
• IGF-1
• Excess Glucocorticoids
• Glucose load
Insulin Growth Factor (IGF)
• Liver synthesis
• peripheral target hormone of GH
 negative feedback
• GH  เพิม่ IGF-1  Induction of Cell
proliferation & Inhibit apoptosis
IGF
• IGF-I & -II  bind IGFBPs
(IGF-binding-protein)
• IGFBP3
 major carrier protein for IGF-1
 level correlate with GH level
Physiology of IGF
• Anabolic effect
 nitrogen retention & ลด Cholesterol
• Induced hypoglycemia
• improve insulin sensitivity
• Induced bone formation & bone turnover
Etiology
98%
Clinical manifestation
Indolent course มักมีอาการมาก่อนพบแพทย์เป็ น 10 ปี
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Acral bony overgrowth
Soft tissue swelling
Generalized organomegaly
Coexisting illness
Generalized organomegaly
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Cardiomegaly
Thyroid enlargement
Macroglossia
Salivary gland
Liver & spleen
Kidney
Prostate
Other sign
• Hyperhidrosis
• deep hollowsounding voice
• oily skin
• Arthropathy
• Kyphosis
• carpal tunnel
syndrome
• proximal muscle
weakness
• acanthosis nigricans
• skin tags
Coexisting illness
Skeletal disorder
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large-joint and axial
arthropathy
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thickened articular cartilage
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periarticular calcifications
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osteophyte overgrowth
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synovitis
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OA
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Kyphoscoliosis
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Vertebral Fracture
Cancer
• Rate of death from CA
colon สู งกว่า normal
population
(standardized mortality
ratio, 2.47; 95% CI,
1.31 to 4.22)
• Risk CA colon 2x
normal
• แนะนา Screening
colonoscopy & F/U
Coexisting illness
Respiratory System
• Central sleep apnea
(central effect of GH)
• OSA
• Soft tissue swelling
• nasal polyps
• macroglossia
• pneumomegaly
Cardiovascular
• Arrthythmia
• HT (irreversible)
• VHD (irreversible)
• Concentric LVH
• Heart failure
(reverse with octreotide)
Prognosis
• แม้จะ Control GH ได้แต่กจ็ ะมี Average age
< คนปกติ 10 ปี
• Common cause of death
 CVS, RS, Malignancy, CVA
• overall standardized mortality ratio of
patients with acromegaly is 1.48
Factor independently predict
longer survival
• growth hormone levels of
less than 2.5 μg per liter
• Younger age
• Shorter duration of disease
• Absence of hypertension
Diagnosis
1. Screening
= IGF-1
2. Confirm =
Glucose
tolerance
test
3. Imaging
Treatment
1. RT
2. Pharmacological
3. Surgery
Transphenoidal surgical
resection
GH กลับเป็ นปกติเร็ว, IGF-1 กลับปกติใน 3-4 day
Response ดีถา้ : GH < 40mcg/L, ก้อน <1cm
Macroadenoma  Cure rate < 50%
ไม่เป็ น 1st line ถ้าก้อนโตมากหรื อ invade cavernous sinus, ผูป้ ่ วย
ปฏิเสธผ่าตัด, ก้อนอยูใ่ กล้ structure ที่เป็ นอันตราย
• 10% จะ recurrence
• Complication = Panhypopituitarism, Injury adjacent st
• Recent surgical advance
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– imaging guidance, navigation and endoscopic approaches
– perioperative pharmacotherapy of the tumor
Radiotherapy
• Slow response (5-15yr) มักต้องใช้ยาไปก่อน
• Late hypopituitarism
(PostRT 10yr  50%)
• Ineffective in normalizing IGF-1
• Indication : recurrence or persistence
after surgery in patients with resistance
to or intolerance of medical treatment
Stereotactic Ablation by
Gamma Knife
• Less evidence about long term result
• Equal effective with similar
Complication
• Benefit
Minimal tissue injury
spare optic tract
Less duration of fraction
Pharmacological therapy
• Somatostatin analogue
• Dopamine agonist
• GH Antagonist
Somatostatin analogue
Mechanism Of Action
• bind somatostatin receptor
• inhibit GH secretion
• inhibit Proliferation of Somatotropes
• Inhibit IGF-1 liver synthesis
Somatostatin analogue
Indication
• Adjuvant therapy before surgery
• No evidence of central compressive
effects
• Too frail to undergo surgery
• Decline surgery
Somatostatin analogue
Drugs in class
• Octreotide  ทนต่อ Plasma degradation
 Potency 40 เท่า Somatostatin
Dose 50 mcg TID  เพิ่มได้จนเป็ น 1500 mcg/d
สามารถกด GH ได้ & normalize IGF-1 ได้ 75%
ช่วยลดขนาด Tumour size ได้เล็กน้อย และจะโตขึ้นถ้า off
• Sandostatin-LAR  sustained release, long
acting (MONTHLY IM)
• Lanreotide  30 mg IM อยูไ่ ด้ 10-14 day
• Pasireotide  Selective activation of
somatostatin receptors, มี additive effect ต่อการกด
GH, ได้ผลแม้ cell ที่ resist ต่อ Octreotide
Dopamine agonist
• Bromocriptine ใช้ high dose >20mg/d เพื่อกด GH
ได้ผล normalize IGF-1 แค่ 10%  poor efficacy
โอกาสได้ผลเพิ่มถ้ามี Co-secretion of PRL
Combine กับ Octreotide  additive benefit
• Newer Generation = Carbergolide
Additive with Somatostatin
GH antagonist  Pegvisomant
• Pegylated Growth analog & substitution of
some Amino acid
• competitive inhibitor to GH
• enhanced affinity for the growth hormone
receptor and prevention of functional growth
hormone–receptor signaling.
• Indication: Resistant or Intolerance to
Octrotide
• Dose  40 mg injection OD  block growth
hormone–mediated generation of IGF-I ประมาณ
90% of patients
GH antagonist  Pegvisomant
• Combine with somatostatin analog
 decrease dose Somatostatin
Additional benefit ในการกด IGF-1 & เพิ่ม
Glucose tolerance
• Disadvantage
 Cost
 No effect on Pitu adenoma
(peripheral tissue action)
Monitoring & Clinical Goal
• First Goal = Symptom control
• Second Goal = Biochemical control
• tight biochemical control is required to reduce
complications and restore adverse rates of death to
control levels.
• Check biochemical test & Pituitary MRI ทุกปี
• Persistent elevation of GH แม้จะ normal IGF-1  บอก
recurrence ซึ่งบอกว่าต้องทา imaging และเริ่ ม start Rx (ใน กรณี
clinical inactive)หรื อเปลี่ยน Rx (ในกรณี Rx อยูแ่ ล้ว)
OTHER
• endogenous pituitary reserve
• cardiovascular function (Including Echo)
• pulmonary status
• sugar control