Pituitary

  • HYPERPROLACTINEMIA
    • In young female: Always rule out Pregnancy
    • If acromegaly (i.e prognathism; enlargement of the nose, lips, and tongue; frontal bossing; dental malocclusion; increased spacing between the teeth; sleep apnea; enlargement of the hands and feet; arthritis of the hips and knees; carpal tunnel syndrome; oily skin; and skin tag) is present, then test for GH excess (MKSAP 16)
      • Prolactin is coproducer with 40 % patients with acromegaly (MKSAP 16)
    • Visual field examination is done if clinical finding is suggestive of optic chasm compression
    • DDx:
      • Prolactinoma (Micro or Macroadenoma)
      • Hypothyroidism
      • Liver Disease
      • Kidney Failure
      • Pregnancy

  • PITUITARY DISORDER
    • Tumor: 
      • Local / Mass Effect:
        • Superior: Headache (Dura), Bitemporal Hemianopia (Optic Chiasma)
        • Inferior: CSF Rhinorrhea
        • Lateral: CN VI, Rarely, ICA

      • Hormonal Effect : 6 Pituitary Hormones (Hypothalamic Hormones affecting release of pituitary hormones)
      1. TSH (TRH)
        • High:
        • Low:
      2. LH / FSH (GNRH)
        • High:
        • Low:
          • Anemia, Poor Libido, ED, Fatigue, Loss of Muscle Mass 
      3. GH (GHRH > Somatostatin (inhibitory) )
        • High:
          • Initial Screening Test:
          • Confirmatory Test: Test for GH suppression with glucose tolerance test 
          • Treatment: Surgery
            • If persistent elevation of IGF-1 after surgery, then we can use Octreotide as medical therapy. 
          • Acromegaly NEJM 2006
        • Low:
          • After traumatic brain injury 40 % patients have GH deficiency (MKSAP 16)
          • Clinical Features: change in body composition (increase in central adiposity and reduction in lean skeletal muscle mass), reduction in quality of life, and decrease in bone mineral density. Increased cardiovascular risk
          • Initial Screening Test: IGF -1 Level
          • Confirmatory Test: GH stimulation test 
      4. ACTH (CRH)
        • High:

        • Low:
      5. Prolactin (Dopamine)
        • High:
          • Testesterone deficiency with associated ED is common in patients with prolactinemia 
          • Treatment: Dopamine Agonist: Cabergoline or Bromocriptine 
          • Prolactinomas NEJM 2010
        • Low:
      6. ADH (Neuroendocrine hormone)
        • Low: 
        • Deficiency of posterior pituitary hormones (ADH, Oxytocin) are usually not associated with benign pituitary tumors 
        • Short axons terminate in hypothalamic nuclei and median eminence 
        • Only long axon, which terminate in posterior pituitary, are affected by sellar lesions 
          • Hence, when DI is present, look for suprasellar, infiltrative or malignant process even if radiologist say it is a pituitary lesoin 
            •  Craniopharyngioma
            • Lymphocytic hypophysitis 
            • Germinoma
            • Metastasis 
        • DI
          • If present on Random samples or after a few hours of abstaining from fluid, a formal water deprivation test is NOT necessary 
          • Paired elevation of Plasma sodium, and inappropriately dilute urine osmolality (<plasma osmolality) 
            • Urine osm > 600 is normal
            • Urine ism between plasma and 600 in presence of elevated plasma sodium (partial DI) 
          • Water Deprivation Test 
            • U Som every hour and plasma sodium every 2 hrs 
            • Continue until one of the following 
              • Urine osm > 600
              • Urine osm stops rising despite increasing plasma sodium
              • Plasma osmolality or Na is > normal 
            • Note: DDAVP causes rise in U ism of > 100 % in COMPLETE Central DI but 15-50 % in PARTIAL Central DI 
              • DDAVP does not cause rise in U som in complete Nephrogenic DI, 
              • < 45 % in partial Nephrogenic DI 
        • SIADH
          • Pharmacological Causes
            • Opiates
            • SSRI, TCA 
          • Management
            • 2 principals to understand the management of SIADH are 
              • Amount of Na in = Amount of Na out
              • Urine Osmolality is fixed
                • Typically U osmolality = 600 (higher or lower can occur) 
                • Giving extra salt will help get rid of extra free water 
            • Do not give NS in patient with SIADH
              • All Na in NS will be lost in more concentrated urine 
              • 308 mosm will be lost in less than 1 L of water. Hence, that extra free water will be retained causing worsening of hyponatremia
              • If Urine Osm is 616, it will be lost in 0.5 L, and 0.5 L of free water will be retained. 
              • If U Osm is 466, it will be lost in 0.75 L, and additional 0.25 L of free water will be retained
              • If U Osm is 308, all 1 L of free H2O of NS will be lost (no free water will be retained)
              • If U Osm is 154, all Na will be lost in 2 L of free water (this of course will not happen, it happens in DI) 
            • If on giving NS, Na drops, it confirms DI. But it is not safe if Na is very low 
            • Treatment principles 
              • Modify Input
                • Decrease free water
                • Increase salt intake 
                  • Salt tab
                • IV fluids with an osmolality > Urine Osmoality 
                  • 3 % hypertonic saline (1026 mosmol) usually fulfills this 
                    • Give slowly
                    • 20-40 cc / hr
                    • Monitor S Na 4-6 hr 
                  • NS occasionally fulfills this if Urine Osm < 308 (hence, important to measure Urine Osmolality) 
              • Modify Output
                • Make Urine more dilute compared to plasma. Hence, more free water will be lost 
                  • Add loop diuretics. Inhibits countercurrent in the medullary loop of hence. Hence, decreased NaCl absorption
                    • Add to salt tablets, or Hypertonic saline
                    • Can also add to NS, and lower urine osmloality to isoosmotic to serum (which is below that of NS) 
                  • Add VRA
    • Lab Evaluation
      • All patients must have
        • TSH, Free T4
        • LH, FSH, Testesterone in Male
        • PRL
        • Morning Cortisol, along with ACTH

    • Hypopituitarism
      • Once pituitary lesion is suspected and MRI is ordered, we also need to do COMPLETE EVALUATION OF PITUITARY FUNCTION SHOULD BE DONE TO LOOK FOR EITHER THE EXCESS OR THE DEFICIENCY of such hormones 
      • lymphocytic hypophysitis can occur during pregnancy or post partum period 
        • Central Adrenal Insufficiency is common in such patients 
      • Prevalance of hypopituitarism
        • 27.5 % after Traumatic Brain Injury (8 % have adrenal insufficiency)
        • 47% after SAH (21 % have adrenal insufficiency) 
        • 17 % of patients receiving Ipilimumba (CTLA-4) ab for Melanoma have autoimmune hypophysitis and panhypopituitarism
          • No need to discontinue Ipilimumab because of the hypophysitis. Hormone replacement is the key 
      • Post-pituitary Surgery monitoring
        • Low dose steroids (2.5 mg prednisone daily)
        • Serial am cortisols and sodium checks for the first 2 weeks post-operatively 
        • 6 week follow up needed for Cosyntropin stimulation test, TFT, Gonadotropin Function evaluation 
      • References:
Additional References:
The Syndrome of Inappropriate Antidiuresis NEJM 2007


Pituitary Apoplexy
Definition: Sudden hemorrhage of infarction of at the pituitary gland resulting in 
  • Headache (76%)
  • Visual field defects (62%)
  • Ocular Palsy (40.4%)
  • AMS (19.3%)
  • N, V, Meningismus, Hemiparesis (rare)
    • Note: Asymptomatic hemorrhage does not equal apoplexy
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