Updated: 9/6/2020

Pituitary Adenoma / Acromegaly

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https://upload.medbullets.com/topic/120094/images/acromegaly.jpg
https://upload.medbullets.com/topic/120094/images/acromegalyteethgapping.jpg
https://upload.medbullets.com/topic/120094/images/frontal_bossing.jpg
https://upload.medbullets.com/topic/120094/images/acromegaly_hands..jpg
Snapshot
  • A 43-year-old man complains of increased hat size and headaches when he wakes up in the morning. Physical exam reveals mild hypertension, prominent jaw with spaces between the teeth, large hands and feet, and generalized muscle weakness.
Introduction
  • Clinical definition
    • excessive growth after skeletal epiphyseal closure due to ↑growth hormone (GH)
  • Epidemiology
    • rare
    • middle age presentation due to insidious onset
    • females and males equally affected
  • Pathogenesis
    • most commonly from a benign pituitary adenoma (> 95%) or hyperplasia
    • less commonly from ectopic oversecretion of GH or growth hormone releasing hormone (GHRH), such as hypothalamic, pulmonary, and gastrointestinal
    • ↑ insulinlike growth factor (IGF-1) mediates effects of GH
  • Genetics
    • not hereditary
    • many have a spontaneous mutation leading to persistent ↑ cyclic adenosine monophosphate (cAMP) in somatotroph cells
  • Associated conditions
    • McCune-Albright syndrome
    • multiple endocrine neoplasia
    • neurofibromatosis
    • tuberous sclerosis
  • Prognosis
    • high morbidity and mortality if untreated due to associated cardiovascular disease, cerebrovascular disease, and malignancy
Presentation
  • Symptoms
    • headache
    • sweating
    • clothes and hat fit tightly
    • amenorrhea or impotence
    • deep voice and slow speech
  • Physical exam
    • hypertension
    • diaphoresis
    • mitral valve regurgitation
    • enlarged head with frontal bossing and deepened facial folds
    • enlarged jaw with increased teeth spacing
    • enlarged fingers and feet
    • skin tags
    • doughy-feeling skin
    • neuropathy
    • muscle weakness
Studies
  • Diagnostic testing
    • studies
      • ↑ IGF1  
        • most sensitive
        • good for screening
      • oral glucose load
        • GH levels 2 hours after 75 g or 100 g glucose tolerance
        • very specific
        • good to confirm diagnosis after positive IGF1 screening
          • GH > 1 μg/L is diagnostic
      • pituitary function
        • may indicate co-secretion or disruption secondary to mass effect
          • prolactin
          • thyroid stimulating hormone (TSH)
          • luteinizing hormone (LH) and follicle-stimulating hormone (FSH)
          • adrenocorticotropic hormone (ACTH)
      • chemistry
        • would show hyperglycemia
    • imaging
      • magnetic resonance imaging (MRI) of the brain for pituitary adenoma  
      • computed tomography (CT) scan
        • if suspicion for non-pituitary secretion
    • radiography
      • to evaluate associated skeletal changes
Differential
  • Gigantism
    • distinguishing factor
      • ↑ GH before skeletal epiphyseal closure
  • Pseudoacromegaly
    • possibly medication-related
    • distinguishing factor
      • no increase in GH and IGF-1
  • Marfan syndrome
    • distinguishing factor
      • collagen disorder
  • Prolactinoma
    • most common secreting pituitary adenoma
    • distinguishing factor
      • prolactin secretion instead of GH
      • no acromegaloid features
Treatment
  • Management approach
    • requires a multimodal approach
      • surgical resection is often first line
      • medical therapy or radiation as neoadjuvant or adjuvant or primary if not amenable to surgery
    • requires long term follow up
  • Surgical
    • rapid and effective
    • endonasal transsphenoidal resection 
      • first-line treatment for nonfunctioning macroadenomas
  • Medical
    • leads to clinical improvement in 70%
    • somatostatin analog inhibits GH production
      • first-line medical treatment
      • octreotide or lanreotide
      • symptomatic management
      • tumor size reduction prior to surgery
      • also indicated in non-pituitary tumors
    • dopamine agonist
      • second-line medical treatment
      • bromocriptine or cabergoline
    • GH receptor antagonist
      • pegvisomant
  • Radiotherapy
    • usually used as adjunct treatment after resection
    • can also be used as first option of treatment
Complications
  • Bitemporal hemianopsia
  • Hypopituitarism
  • Cardiomyopathy and heart failure
    • most common cause of death
  • Diabetes
  • Colon cancer
  • Sleep apnea
  • Carpal tunnel

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Questions (5)
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(M2.EC.17.94) A 47-year-old female with a history of hypertension presents to your outpatient clinic for numbness, tingling in her right hand that has been slowly worsening over the last several months. She has tried using a splint but receives minimal relief. She is an analyst for a large consulting firm and spends most of her workday in front of a computer. Upon examination, you noticed that the patient has a prominent jaw and her hands appear disproportionately large. Her temperature is 99 deg F (37.2 deg C), blood pressure is 154/72 mmHg, pulse is 87/min, respirations are 12/min. A fasting basic metabolic panel shows: Na: 138 mEq/L, K: 4.1 mEq/L, Cl: 103 mEq/L, CO2: 24 mEq/L, BUN: 12 mg/dL, Cr: 0.8 mg/dL, Glucose: 163 mg/dL. Which of the following tests would be most helpful in identifying the underlying diagnosis?

QID: 104419
1

Measurement of serum morning cortisol levels and dexamethasone suppression test

0%

(0/14)

2

Measurement of insulin-like growth factor 1 alone and growth hormone levels after oral glucose

79%

(11/14)

3

Measurement of thyroid stimulating hormone

0%

(0/14)

4

Measurement of serum growth hormone alone

0%

(0/14)

5

Measurement of insulin-like growth factor 1 levels alone

21%

(3/14)

M 6 C

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