# Clinical Cases: Endocrine Pharmacology

## Case 1: Thyroid Storm Management

### Patient Demographics
- **Age:** 32 years
- **Sex:** Female
- **Occupation:** Marketing executive

### Chief Complaint
"I feel like my heart is racing out of my chest and I can't stop sweating."

### History of Present Illness
A 32-year-old woman with known Graves' disease presents to the emergency department with palpitations, fever, agitation, and profuse sweating. She was diagnosed with Graves' disease 8 months ago and was started on methimazole 10 mg three times daily. She admits she stopped taking her medication 3 weeks ago because she "felt fine" and was worried about side effects she read about online. Two days ago she developed an upper respiratory infection and started taking over-the-counter cold medications. Today she developed high fever, racing heart, tremors, nausea, vomiting, and diarrhea. Her husband notes she has been confused and agitated.

### Past Medical History
- Graves' disease (diagnosed 8 months ago)
- No prior thyroid storm
- No allergies

### Physical Examination
- **Vital Signs:** T 39.8C (103.6F), HR 148 bpm (irregular), BP 170/60 mmHg (wide pulse pressure), RR 24/min
- **General:** Diaphoretic, agitated, tremulous, appears acutely ill
- **HEENT:** Lid lag, proptosis (exophthalmos), stare; thyroid diffusely enlarged, non-tender, bruit present
- **Cardiovascular:** Tachycardic, irregularly irregular (atrial fibrillation), hyperdynamic precordium
- **Neurologic:** Agitated, disoriented to time; fine tremor of outstretched hands
- **Skin:** Warm, moist, flushed

### Workup
- **TSH:** <0.01 mIU/L (undetectable)
- **Free T4:** 7.8 ng/dL (normal 0.8-1.8)
- **Free T3:** 18.2 pg/mL (normal 2.3-4.2)
- **ECG:** Atrial fibrillation with rapid ventricular response (148 bpm)
- **CXR:** No acute cardiopulmonary process
- **BMP:** Glucose 142 mg/dL; otherwise normal
- **CBC:** WBC 11,200 with normal differential
- **Burch-Wartofsky Score:** 65 (highly suggestive of thyroid storm; >45 indicates storm)

### Diagnosis
**Thyroid Storm** (life-threatening thyrotoxicosis) precipitated by:
1. Medication non-adherence (stopped methimazole)
2. Acute illness (URI - infectious trigger)

### Treatment Plan

**IMMEDIATE MANAGEMENT - Multi-Modal Approach:**

**1. BLOCK NEW HORMONE SYNTHESIS - Thionamides:**
- **Propylthiouracil (PTU) 500-1000 mg loading dose, then 250 mg every 4 hours**
- PTU preferred over methimazole in thyroid storm because it ALSO blocks peripheral T4 to T3 conversion
- Mechanism: Inhibits thyroid peroxidase (TPO), blocking iodine organification and coupling

**2. BLOCK HORMONE RELEASE - Iodine (MUST give AFTER thionamide):**
- **Potassium iodide (SSKI) 5 drops every 6 hours** OR
- **Lugol's solution 10 drops every 8 hours**
- Wait at least 1 hour after PTU before giving iodine
- Mechanism: Wolff-Chaikoff effect - high iodine acutely inhibits hormone release
- **CRITICAL:** If given before thionamide, iodine will provide substrate for MORE hormone synthesis

**3. BLOCK PERIPHERAL CONVERSION (T4 to T3):**
- **Hydrocortisone 100 mg IV every 8 hours** (or dexamethasone 2 mg IV every 6 hours)
- Glucocorticoids block 5'-deiodinase (T4 to T3 conversion)
- Also address potential relative adrenal insufficiency in severe thyrotoxicosis
- PTU also contributes to blocking peripheral conversion

**4. BLOCK PERIPHERAL EFFECTS - Beta-Blocker:**
- **Propranolol 60-80 mg PO every 4-6 hours** (or IV if unable to take PO)
- Controls tachycardia, hypertension, tremor, agitation
- Propranolol also has mild effect on blocking T4 to T3 conversion
- Alternative: Esmolol drip if need rapid titration or concern for beta-blocker intolerance

**5. SUPPORTIVE CARE:**
- ICU admission
- IV fluids (high metabolic rate causes significant fluid losses)
- Cooling blankets for hyperthermia (avoid aspirin - displaces T4 from binding proteins)
- Acetaminophen for fever
- Treat underlying precipitant (antibiotics if infection suspected)
- Rate control for atrial fibrillation

**ORDER OF ADMINISTRATION:**
1. Beta-blocker (immediate symptom control)
2. PTU (block synthesis)
3. Wait 1 hour
4. Iodine (block release)
5. Glucocorticoid (block conversion, adrenal support)

### Medication Mechanisms Summary

| Drug | Mechanism | Timing |
|------|-----------|--------|
| PTU | Blocks TPO (synthesis) + blocks T4-to-T3 conversion | First-line, give immediately |
| Methimazole | Blocks TPO only (no peripheral conversion block) | Alternative if PTU unavailable |
| Iodine | Wolff-Chaikoff effect (blocks release) | AFTER thionamide (1+ hour) |
| Propranolol | Beta-blockade + mild T4-to-T3 block | Immediate |
| Glucocorticoids | Blocks T4-to-T3 conversion; adrenal support | With other therapies |

### Clinical Course
- HR improved to 95 bpm within 6 hours of beta-blocker
- Temperature normalized by 24 hours
- Mental status cleared by 48 hours
- Converted to sinus rhythm after 3 days
- Transitioned to oral methimazole after stabilization
- Referred for definitive therapy (radioactive iodine vs surgery)

### Follow-up Plan
- Continue PTU until stable, then transition to methimazole 10-20 mg BID
- Taper glucocorticoids
- Definitive therapy planning: RAI vs thyroidectomy
- Emphasize medication adherence
- Monitor for agranulocytosis (rare but serious thionamide side effect) - check CBC if fever/sore throat

### Clinical Pearl
Thyroid storm is a medical emergency with mortality rates of 10-30% even with treatment. The key to management is a multi-pronged approach: block synthesis (thionamides), block release (iodine - but AFTER thionamides), block peripheral conversion (glucocorticoids, PTU), and block peripheral effects (beta-blockers). PTU is preferred over methimazole in thyroid storm specifically because PTU also inhibits peripheral T4-to-T3 conversion. Iodine must be given at least 1 hour after thionamides to prevent providing substrate for increased hormone synthesis. Common precipitants include infection, medication non-adherence, surgery, trauma, and iodine load (CT contrast). All patients with Graves' disease should be counseled about the importance of medication adherence and recognizing warning signs.

### Clinical Image
![Graves Disease Eye Findings](case_01_image.jpg)

*Clinical photograph demonstrating exophthalmos (proptosis) and lid retraction characteristic of Graves' ophthalmopathy. These findings result from autoimmune inflammation and expansion of orbital tissues.*

**Image Source:** Wikimedia Commons - "Proptosis and lid retraction from Graves' Disease"
**License:** CC BY-SA 4.0
**URL:** https://commons.wikimedia.org/wiki/File:Proptosis_and_lid_retraction.jpg

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## Case 2: Adrenal Crisis in a Patient on Chronic Glucocorticoids

### Patient Demographics
- **Age:** 58 years
- **Sex:** Male
- **Occupation:** Accountant

### Chief Complaint
"I feel extremely weak and dizzy. I think I'm going to pass out."

### History of Present Illness
A 58-year-old man with polymyalgia rheumatica on chronic prednisone therapy presents with acute weakness, dizziness, nausea, vomiting, and abdominal pain. He has been taking prednisone 15 mg daily for 2 years for polymyalgia rheumatica. One week ago, his rheumatologist tapered his prednisone from 15 mg to 5 mg daily because his symptoms were well-controlled. Three days ago, he developed acute gastroenteritis with vomiting and diarrhea, and he has been unable to keep his prednisone down. This morning, he felt so weak he could barely get out of bed. His wife notes he appears confused.

### Past Medical History
- Polymyalgia rheumatica (2 years, on chronic prednisone)
- Type 2 diabetes
- Hypertension
- No history of adrenal disease

### Medications (Prior to Illness)
- Prednisone 5 mg daily (recently tapered from 15 mg)
- Metformin 1000 mg BID
- Lisinopril 20 mg daily

### Physical Examination
- **Vital Signs:** BP 78/52 mmHg, HR 112 bpm, T 37.2C, orthostatic (unable to stand)
- **General:** Appears acutely ill, lethargic, weak
- **Skin:** No hyperpigmentation (unlike primary adrenal insufficiency)
- **Cardiovascular:** Tachycardic, regular rhythm, weak peripheral pulses
- **Abdomen:** Diffuse tenderness, hypoactive bowel sounds
- **Neurologic:** Lethargic but arousable, oriented x 2

### Workup
- **BMP:** Na 128 mEq/L (low), K 5.4 mEq/L (high-normal), Glucose 58 mg/dL (low), Cr 1.4 mg/dL
- **CBC:** WBC 4,200 (eosinophils mildly elevated at 8%)
- **Random cortisol:** 2.1 mcg/dL (inappropriately low for acute stress; should be >18-20)
- **ACTH:** 8 pg/mL (low-normal) - suggests secondary/tertiary adrenal insufficiency
- **Lactate:** 3.2 mmol/L (elevated)

### Diagnosis
**Adrenal Crisis (Acute Adrenal Insufficiency)** secondary to:
1. HPA axis suppression from chronic glucocorticoid therapy
2. Rapid glucocorticoid taper
3. Acute physiologic stress (gastroenteritis) without stress-dose steroids
4. Inability to absorb oral steroids due to vomiting

### Pathophysiology
- Chronic exogenous glucocorticoids suppress the hypothalamic-pituitary-adrenal (HPA) axis
- Adrenal glands atrophy and cannot mount appropriate cortisol response to stress
- Rapid taper or acute illness without stress dosing precipitates crisis
- Secondary adrenal insufficiency (from exogenous steroids) differs from primary:
  - ACTH is low (not elevated)
  - Typically no hyperpigmentation
  - Mineralocorticoid function often preserved (aldosterone regulated by renin-angiotensin, not ACTH)

### Treatment Plan

**IMMEDIATE RESUSCITATION:**
1. **IV Access and Fluids:**
   - Normal saline bolus 1-2 L over first hour
   - D5NS if hypoglycemic
   - Aggressive fluid resuscitation (patients are often severely volume depleted)

2. **Stress-Dose Glucocorticoids:**
   - **Hydrocortisone 100 mg IV bolus IMMEDIATELY**
   - Then hydrocortisone 50 mg IV every 6 hours (or 200 mg/24h continuous infusion)
   - Hydrocortisone preferred because it has mineralocorticoid activity
   - Alternative: Dexamethasone 4 mg IV if diagnostic testing pending (doesn't interfere with cortisol assay)

3. **Identify and Treat Precipitant:**
   - IV antiemetics for nausea
   - Supportive care for gastroenteritis
   - Evaluate for infection (though fever may be absent in adrenal crisis)

4. **Monitor:**
   - Continuous telemetry
   - Serial electrolytes (Na, K, glucose)
   - Hemodynamic monitoring

**WHY HYDROCORTISONE?**
- At stress doses (100+ mg/day), hydrocortisone provides sufficient mineralocorticoid effect
- No need for separate fludrocortisone during acute crisis
- If using dexamethasone (no mineralocorticoid activity), may need fludrocortisone

### Glucocorticoid Equivalencies and Properties

| Glucocorticoid | Equivalent Dose | Relative Glucocorticoid Potency | Relative Mineralocorticoid Potency | Duration |
|----------------|-----------------|--------------------------------|-----------------------------------|----------|
| Hydrocortisone | 20 mg | 1 | 1 | Short |
| Prednisone | 5 mg | 4 | 0.8 | Intermediate |
| Methylprednisolone | 4 mg | 5 | 0.5 | Intermediate |
| Dexamethasone | 0.75 mg | 25 | 0 | Long |
| Fludrocortisone | - | 10 | 125 | - |

### Recovery and Transition

**After Stabilization (24-48 hours):**
1. Taper IV hydrocortisone as clinical status improves
2. Transition to oral hydrocortisone 20 mg AM / 10 mg PM (or prednisone equivalent)
3. Taper gradually back to maintenance dose over days to weeks
4. Do NOT rapidly return to previous low dose

**STRESS DOSING EDUCATION (Critical):**

| Situation | Stress Dose |
|-----------|-------------|
| Minor illness (cold, mild GI) | Double or triple daily dose for 2-3 days |
| Moderate illness (fever >38C, flu) | Triple dose; consider IM/IV if vomiting |
| Major surgery | Hydrocortisone 100 mg IV pre-op, then 50 mg q8h x 24-48h, taper |
| Severe illness/trauma | Hydrocortisone 100 mg IV q8h until stable |
| Unable to take oral | IM hydrocortisone 100 mg; emergency injection kit at home |

### Prevention and Patient Education

1. **Medical alert bracelet:** Must wear at all times
2. **Emergency injection kit:** Prescribe hydrocortisone 100 mg IM for home use
3. **Sick day rules:** Double/triple dose during illness; seek care if vomiting
4. **Gradual tapers:** Never stop chronic steroids abruptly
5. **Inform all providers:** Patient on chronic steroids needs stress dosing for procedures
6. **HPA axis recovery:** Takes 6-12 months after stopping chronic steroids; may need coverage during this period

### Clinical Pearl
Any patient on glucocorticoids equivalent to prednisone >5 mg daily for >3 weeks has potential HPA axis suppression and is at risk for adrenal crisis if steroids are stopped abruptly or during physiologic stress. The triad of hypotension, hyponatremia, and hypoglycemia in a patient on chronic steroids should prompt immediate consideration of adrenal crisis - treat empirically with IV hydrocortisone before waiting for confirmatory labs. Chronic glucocorticoid-induced adrenal insufficiency is SECONDARY (pituitary suppression), so ACTH is low and hyperpigmentation is absent. At physiologic stress doses of hydrocortisone (>50 mg/day), additional mineralocorticoid is not needed. Patient education about sick day rules and medical alert identification is essential to prevent future crises.

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