What Causes Pituitary Adenoma?

A pituitary adenoma (a type of benign tumor) may be caused by a number of genetic conditions. It can lead the gland and surrounding tissue to produce harmfully high levels of hormones.

Pituitary adenomas are benign (not cancerous) tumors that affect the pituitary gland. Even though they are benign, pituitary adenomas can cause health problems because they are close to the brain, they may invade nearby tissues (such as the skull or the sinuses), and many of them produce excess hormones.

Pituitary cancers (carcinomas) are rare.

Symptoms of a pituitary adenoma may include: 

• Vision problems (blurred or double vision, drooping eyelid) 
• Headaches 
• Nausea or vomiting 
• Altered sense of smell 
• Sexual dysfunction 
• Depression 
• Fatigue 
• Infertility 
• Growth problems 
• Osteoporosis 
• Unexplained weight changes
• Easy bruising 
• Joints aches
• Carpal tunnel syndrome 
• Irregular menstrual periods
• Early menopause 
• Muscle weakness 
• Nipple discharge not associated with childbirth or nursing (galactorrhea)

The cause of most pituitary adenomas is unknown.

Risk factors for pituitary adenomas include:

• Family history
• Genetic syndromes
  • Multiple endocrine neoplasia, type I (MEN1)
  • Multiple endocrine neoplasia, type IV (MEN4)
  • McCune-Albright syndrome
  • Carney complex

In addition to a physical examination, pituitary adenomas are also diagnosed with the following tests: 

• Vision testing to check for visual field deficits, such as loss of peripheral vision
• Blood tests 
  • Growth hormone and insulin-like growth factor-1 (IGF-1) 
  • Cortisol and ACTH
  • Blood prolactin levels 
  • Luteinizing hormone (LH) 
  • Follicle-stimulating hormone (FSH) 
  • Thyrotropin (TSH) and thyroid hormones
  • Pituitary hormone levels
  • Sodium levels 
  • Glucose levels
  • Osmolality (total salt concentration)
  • Venous blood sampling
• Testing for diabetes insipidus
  • 24-hour urine test
  • Glucose suppression test
  • Water deprivation study
• Imaging tests
  • Magnetic resonance imaging (MRI) scan
  • Computed tomography (CT) scan
• Tests of pituitary tissue samples (biopsy)

Treatment used for pituitary adenomas includes one or more of the following: 

• Surgical removal of the tumor 
• Radiation therapy 
  • Standard external beam radiotherapy
  • Proton beam treatment
  • Stereotactic radiosurgery (Gamma Knife, Novalis BrainLab and CyberKnife) 
• Medication therapy to shrink or eradicate the tumor
  • For growth hormone-secreting tumors (acromegaly/gigantism)
    • Ocreotide (Sandostatin)
    • Lanreotide (Somatulin Depot)
    • Cabergoline and/or bromocriptine
    • Pegvisomant (Somavert)
  • For ACTH-secreting tumors (Cushing’s syndrome/disease)
    • Ketoconazole (Nizoral)
    • Mitotane (Lysodren)
    • Metyrapone (Metopirone)
    • Mifepristone (Korlym)