# Clinical Cases: Hypothalamus and Pituitary Anatomy and Physiology

## Case 1: Pituitary Macroadenoma with Visual Field Defects

### Patient Demographics
- **Age:** 52 years
- **Sex:** Female
- **Occupation:** Accountant

### Chief Complaint
"I've been having headaches and bumping into things on my sides."

### History of Present Illness
A 52-year-old woman presents with a 6-month history of worsening headaches and progressive visual difficulties. She reports bumping into door frames and has had two minor car accidents when changing lanes because she did not see vehicles approaching from the side. Her husband has noticed that she has been more fatigued and has lost interest in activities she previously enjoyed. She also reports amenorrhea for the past 8 months, which she attributed to menopause.

### Physical Examination
- **Vital Signs:** BP 118/72 mmHg, HR 58 bpm, Temp 36.4°C
- **General:** Appears fatigued, pale complexion
- **HEENT:** Visual field testing reveals bitemporal hemianopia
- **Neurologic:** Cranial nerves otherwise intact, no papilledema
- **Skin:** Dry, cool to touch

### Workup
- **Laboratory Studies:**
  - TSH: 0.8 mIU/L (low-normal)
  - Free T4: 0.6 ng/dL (low, normal 0.9-1.7)
  - Prolactin: 85 ng/mL (elevated, normal <25)
  - Cortisol (8 AM): 4.2 μg/dL (low, normal 6-23)
  - FSH: 2.1 mIU/mL (low for postmenopausal)
  - LH: 1.8 mIU/mL (low for postmenopausal)
  - IGF-1: 65 ng/mL (low for age)
- **MRI Brain with Contrast:** 2.5 cm pituitary macroadenoma with suprasellar extension compressing the optic chiasm

### Diagnosis
**Non-functioning pituitary macroadenoma** causing:
1. Bitemporal hemianopia (optic chiasm compression)
2. Hypopituitarism (secondary hypothyroidism, secondary adrenal insufficiency, secondary hypogonadism, GH deficiency)
3. Stalk effect hyperprolactinemia (disruption of dopamine inhibition)

### Treatment
1. Immediate stress-dose glucocorticoids (hydrocortisone 100 mg IV) given before any other intervention
2. Transsphenoidal surgical resection of the adenoma
3. Post-operative hormone replacement:
   - Hydrocortisone replacement started BEFORE levothyroxine
   - Levothyroxine for secondary hypothyroidism
   - Estrogen/progesterone therapy consideration
4. Close monitoring for post-operative diabetes insipidus

### Clinical Pearl
The mild prolactin elevation (85 ng/mL) in this case represents "stalk effect" rather than a true prolactinoma. The tumor is compressing the pituitary stalk, interrupting dopamine delivery to lactotrophs. A true prolactinoma of this size would typically produce prolactin levels >200 ng/mL. This distinction is critical because prolactinomas respond to dopamine agonist therapy, while non-functioning adenomas require surgery for mass effect.

### Clinical Image
![Pituitary Macroadenoma MRI](case_01_image.jpg)

*Coronal T1-weighted MRI with gadolinium showing a pituitary macroadenoma with suprasellar extension and optic chiasm compression.*

**Image Source:** Wikimedia Commons - "Pituitary macroadenoma" by Hellerhoff
**License:** CC BY-SA 3.0
**URL:** https://commons.wikimedia.org/wiki/File:Hypophysenadenom_MRT_coronar.jpg

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## Case 2: Sheehan Syndrome (Postpartum Pituitary Necrosis)

### Patient Demographics
- **Age:** 34 years
- **Sex:** Female
- **Occupation:** Elementary school teacher

### Chief Complaint
"I've been exhausted since my delivery 6 weeks ago and I can't produce any breast milk."

### History of Present Illness
A 34-year-old woman, G2P2, presents 6 weeks postpartum with profound fatigue, inability to lactate, and ongoing amenorrhea. Her delivery was complicated by postpartum hemorrhage requiring blood transfusion after retained placenta. She lost approximately 2 liters of blood and had a period of hypotension (BP 70/40 mmHg) for about 45 minutes before stabilization. Since delivery, she has been unable to breastfeed despite multiple attempts and lactation consultation. She reports feeling cold, constipated, and has noticed hair loss.

### Physical Examination
- **Vital Signs:** BP 92/60 mmHg (orthostatic drop), HR 54 bpm, Temp 35.8°C
- **General:** Pale, lethargic appearing, dry skin
- **Breasts:** No engorgement, no galactorrhea with expression
- **Thyroid:** Normal size, non-tender
- **Neurologic:** Delayed relaxation of ankle reflexes

### Workup
- **Laboratory Studies:**
  - Sodium: 128 mEq/L (low)
  - TSH: 1.2 mIU/L (inappropriately normal)
  - Free T4: 0.5 ng/dL (low)
  - Prolactin: 2 ng/mL (very low, expected postpartum elevation)
  - Cortisol (AM): 2.8 μg/dL (low)
  - ACTH: 8 pg/mL (inappropriately normal/low)
  - FSH/LH: Low
- **MRI Pituitary:** Empty sella or partially empty sella with pituitary tissue flattened against sellar floor

### Diagnosis
**Sheehan syndrome** (postpartum pituitary necrosis) with panhypopituitarism

### Treatment
1. Emergency glucocorticoid replacement (hydrocortisone)
2. Levothyroxine (started after cortisol replacement is established)
3. Consider estrogen/progesterone for bone protection
4. Long-term monitoring of all pituitary axes
5. Education about stress dosing of glucocorticoids

### Clinical Pearl
Sheehan syndrome occurs due to ischemic necrosis of the enlarged, hyperemic pituitary gland of pregnancy when there is significant postpartum hemorrhage and hypotension. The pituitary approximately doubles in size during pregnancy due to lactotroph hyperplasia, making it vulnerable to hypoperfusion. The classic triad is failure to lactate, amenorrhea, and features of hypopituitarism. The inability to lactate is often the first recognized sign, as prolactin deficiency prevents milk production.

### Clinical Image
![Empty Sella MRI](case_02_image.jpg)

*Sagittal T1-weighted MRI showing an empty sella with CSF filling the sella turcica and flattened pituitary tissue.*

**Image Source:** Radiopaedia - "Empty sella syndrome"
**License:** CC BY-NC-SA 3.0
**URL:** https://radiopaedia.org/cases/empty-sella-syndrome

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## Case 3: Pituitary Apoplexy

### Patient Demographics
- **Age:** 48 years
- **Sex:** Male
- **Occupation:** Construction supervisor

### Chief Complaint
"I have the worst headache of my life and I can't see properly."

### History of Present Illness
A 48-year-old man with no significant past medical history presents to the emergency department with sudden onset of severe headache that began 3 hours ago while lifting heavy equipment at work. The headache is described as "thunderclap" in nature, with associated nausea, vomiting, and progressive visual changes. He reports seeing double and notes that his right eyelid is drooping. His wife states he seems confused compared to his baseline.

### Physical Examination
- **Vital Signs:** BP 88/52 mmHg, HR 110 bpm, Temp 37.8°C
- **General:** Diaphoretic, appears acutely ill
- **HEENT:**
  - Right ptosis with dilated pupil (CN III palsy)
  - Restricted eye movements on right
  - Visual field testing limited by mental status but appears to have decreased temporal fields bilaterally
- **Neurologic:** Oriented to person only, meningismus present
- **Cardiovascular:** Tachycardia, regular rhythm

### Workup
- **Laboratory Studies:**
  - Sodium: 132 mEq/L
  - Glucose: 68 mg/dL
  - Cortisol (random): 3.1 μg/dL (inappropriately low for acute stress)
  - Prolactin: 156 ng/mL (elevated)
- **CT Head:** Sellar mass with hemorrhage
- **MRI Pituitary:** 2.0 cm pituitary mass with areas of hemorrhage and necrosis, suprasellar extension with optic chiasm compression

### Diagnosis
**Pituitary apoplexy** (hemorrhagic infarction of a pituitary adenoma)

### Treatment
1. **Immediate:** IV hydrocortisone 100 mg bolus (critical before any other intervention)
2. **Fluid resuscitation** for hypotension
3. **Urgent neurosurgical consultation** for transsphenoidal decompression given:
   - Visual impairment
   - Altered mental status
   - Cranial nerve palsy
4. Post-operative hormone evaluation and replacement as needed

### Clinical Pearl
Pituitary apoplexy is a medical and often surgical emergency. The sudden hemorrhage or infarction within a pituitary adenoma (often previously undiagnosed) causes rapid expansion with compression of surrounding structures. The clinical presentation includes sudden severe headache, visual loss, ophthalmoplegia (due to cavernous sinus involvement), and altered mental status. Acute adrenal insufficiency may occur and is life-threatening. Immediate glucocorticoid administration should not be delayed for diagnostic testing. Surgery is indicated urgently when there is significant visual impairment or altered consciousness.

### Clinical Image
![Pituitary Apoplexy CT](case_03_image.jpg)

*Axial CT scan showing hemorrhage within an enlarged pituitary gland (pituitary apoplexy).*

**Image Source:** Radiopaedia - "Pituitary apoplexy"
**License:** CC BY-NC-SA 3.0
**URL:** https://radiopaedia.org/cases/pituitary-apoplexy-1