hyperprolactinemia
HYPERPROLACTINEMIA
Hyperprolactinemia is the presence of elevated prolactin levels that occurs in about one-thirds of patients w/ chronic kidney disease & resolves after successful transplantation.
It may cause visual field defects or headache in both men and women.
In women, signs and symptoms include menstrual irregularity, galactorrhea, infertility, vaginal dryness, dyspareunia, loss of libido and reduction in vertebral bone density (in sustained, pronounced hyperprolactinemia).
While in men, signs and symptoms include diminished libido, hypogonadism, gonadotrophin suppression, osteopenia, decreased muscle mass, and decreased facial hair that may occur in prolonged hyperprolactinemia.

Evaluation

  • Physiologic causes, renal failure, parasellar tumors, hypothyroidism & drug-induced hyperprolactinemia should be ruled out before extensive evaluation

Measure Fasting Prolactin (PRL) Level

  • Normal range: <30 ng/mL normal fasting prolactin (PRL) level
  • Diagnostic range: >250 ng/mL (w/ physiologic causes & drug-induced causes ruled out) usually indicates prolactinoma
    • A prolactinoma is less likely w/ prolactin (PRL) level <100 ng/mL
    • Several measurements should be made to confirm diagnosis

Radiologic Evaluation

  • Should be performed if there is no obvious cause of hyperprolactinemia & if tumor is suspected
    • Physician must decide whether a radiographic study is warranted if prolactin (PRL) level <250 ng/mL but >100 ng/mL
  • Magnetic resonance imaging (MRI) w/ gadolinium enhancement is the imaging study of choice
    • Computed tomography (CT) w/ contrast may also be used
    • Serum prolactin (PRL) >200 ng/mL indicates prolactinoma
      • Prolactinomas are classified as macroadenoma if the size is ≥10 mm; microadenoma if <10 mm in size
    • Serum prolactin (PRL) <200 ng/mL w/ large pituitary mass usually indicates hyperprolactinemia secondary to stalk compression
    • Magnetic resonance imaging (MRI) & computed tomography (CT) scan normal & no obvious cause, patient is said to have idiopathic hyperprolactinemia

Laboratory Tests

  • To establish the diagnosis of hyperprolactinemia, it is recommended to have a single measurement of serum prolactin
    • A level above the upper limits confirms the diagnosis
  • Careful history & physical exam including cranial nerve examination
    • Check for galactorrhea, visual field defects, signs of cirrhosis, hair growth pattern on the body, etc
    • Drug history
  • Blood chemistry [blood urea nitrogen (BUN), creatinine]
  • Other pituitary hormones (eg testosterone levels, cortisol, insulin growth factor-1) as necessary
  • Pregnancy test
  • To rule out macroprolactinemia, polyethylene glycol precipitation is recommended
  • Thyroid function tests (to rule out hypothyroidism)
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