Pituitary Adenoma (functioning and nonfunctioning)

“🚧 Page Under Construction 🚧”

FACTS

Nonfunctioning adenomas:
Functioning adenomas:

HPI

Labs
Prolactinoma
Acromegaly
Cushings
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- cortisol: loss of diurnal variations
- ACTH: normal or elevated
- ↑ 24h urine-free cortisol
- CRH: low
- Low-dose dexamethasone test: failure to suppress cortisol
 
Symptoms
Prolactinoma
Acromegaly
Cushings
Women
Galactorrhea, menstrual irregularities, infertility, decreased libido, Vaginal dryness, dyspareunia

Men
Decreased libido, ED, infertility, Gynecomastia (rare), Decreased muscle mass
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- hx adrenalectomy (Nelson syndrome)
- weight gain
- HTN
- amenorrhea (women)
- impotence (men)
- reduced libido (all)
- skin hyperpigmentation
- atrophic, tissue paper thin skin
- poor wound healing
- depression, emotional lability, dementia
- osteoporosis
- muscle wasting
- easy fatigue
- acne
- sepsis (advanced)
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PHYSICAL EXAM

universal physical exam
Prolactinoma
Acromegaly
Cushings
gynecomastia
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easy bruising, hirsutism, proximal muscle weakness, facial plethora or “moon facies,” purple striae, “buffalo hump”

IMAGING

NFA
Prolactinoma
Acromegaly
Cushings
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T1+c: moderate to bright, heterogenously enhancing (see below)
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A/P
Initial diagnosis
  • ENT consult
  • Optho c/s for baseline HVF/OCT
  • Pituitary labs:
    • HPA: AM cortisol (0700), ACTH, random cortisol
    • Prolactin: random prolactin (+/- dilution)
    • IGF-1
    • TSH / FT4
    • Gonadal axis:
      • serum FSH/LH
      • estradiol in women, testosterone in men
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Hook Effect for Prolactinomas:
  • Beware of this when prolactin seems suspiciously normal on a giant tumor.
  • This can cause falsely negative prolactin levels in prolactinomas. The science behind this is that immunoassays use a “sandwich” method whereby on Ab captures prolactin and another labeled Ab then binds this. If prolactin is profoundly high, both buns of the sandwich will be consumed without making any sandwiches that can be detected.
  • The way around this is to dilute the serum sample → if prolactin rises, hook effect was causing prolactin level to be artificially low.
 
Treatment
Surgery is generally the mainstay of treatment for large, symptomatic tumors and functional tumors that fail medical treatment..
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NFA
Prolactinoma
Acromegaly
Cushings
Medical
None
cabergoline
bromocriptine
octreotide
D2 agonists (20% respond)
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Surgical
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Radiation
16-18 Gy
25 Gy
25 Gy
25 Gy
 
General notes:
  • Radiation risks:
    • anterior pituitary deficits 10-50%
    • If max dose to optic apparatus 12-13 Gy, visual loss < 2%
 

Subtypes of Pituitary Adenoma

Nonfunctioning adenomas

 

Prolactinoma

 
Imaging: typically macroadenomas are heterogenously enhancing however can also be hypo-enhancing if microadenomas
Middle aged male with a medically refractory prolactinoma underwent EEA of a heterogenosly enhancing mass on T1+c (RIGHT) with inferior chiasmal abutment on T2 sequencing (LEFT)
Middle aged male with a medically refractory prolactinoma underwent EEA of a heterogenosly enhancing mass on T1+c (RIGHT) with inferior chiasmal abutment on T2 sequencing (LEFT)
Treatment:
  • bromocriptine (D agonist, semi-synthetic ergot alkaloid) reduces tumor size in 5-8 weeks in ~75% of patients
  • cabergoline (D agonist, ergot alkaloid that is more receptor selective) may be even more potent than bromocriptine

Acromegaly

  • GH secreting tumors can co-secrete prolactin too
  • Medical treatment:
    • lisuride, octreotide, pegvisomant
    • D2 agonists in ~20% work (bromocriptine, cabergoline)
Post-operative testing:
  • Cure = nadir GH of 0.4 μg/L on OGTT
    • administer 75g dissolved glucose after overnight fasting
    • serum measurements of GH in 30 min interval
  • takes ~10 months for IGF-1

Cushing’s Disease

Cushing’s Disease = Cushing’s Syndrome 2/2 pituitary adenoma
Diagnostics
24h urine cortisol (Gold standard)
PM serum cortisol
midnight salivary cortisol
Inferior petrosal sinus sampling (IPSS):
  • sample ACTH from petrosal veins (drain pituitary gland)
  • compare ACTH with systemic blood levels to determine pituitary vs. ectopic ACTH production
  • also establishes laterality of ACTH production (R vs L) which is useful if microadenoma not structurally obvious on imaging
Nelson’s syndrome:
  • occurs after total bilateral adrenalectomies (TBA) for CD usually 1-4 years after
  • pathophys: continued growth of ACTH secreting cells
    • TBA → hypercortisolism fixed → ↑ CRH → corticotroph adenomas have an exaggerated response to CRH → ↑ growth
  • Treatment:
    • first line:
    • may consider: D agonists, serotonin agonists, VPA, somatostatin analogues, and rosiglitazone.