Hypothyroidism
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# **HYPOTHYROIDISM — COMPLETE NOTE**
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## **1. DEFINITION**
Hypothyroidism is a clinical state resulting from **decreased production or action of thyroid hormones (T3, T4)**, leading to generalized slowing of metabolic processes.
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## **2. PATHOPHYSIOLOGY (FULL FLOW)**
* ↓ T3/T4 → ↑ TRH (hypothalamus) → ↑ TSH (pituitary) (primary hypo).
* Reduced thyroid hormone levels cause:
* ↓ Basal metabolic rate
* ↓ thermogenesis → cold intolerance
* ↓ lipid metabolism → ↑ LDL, ↑ triglycerides
* ↓ cardiac output → bradycardia, fatigue
* ↓ GI motility → constipation
* Mucopolysaccharide deposition → **myxedema**
* ↓ Erythropoiesis → normocytic anemia
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## **3. CAUSES**
### **Primary Hypothyroidism (95%)**
1. **Autoimmune (Hashimoto thyroiditis)** — most common
2. Iatrogenic:
* Post-thyroidectomy
* Post-radioiodine ablation
* Radiation of neck
3. Drugs:
* Amiodarone
* Lithium
* Interferon-α
* TKIs (sunitinib)
4. Iodine disorders:
* Deficiency (common worldwide)
* excess iodine (Wolff–Chaikoff effect)
5. Congenital:
* Thyroid agenesis/dysgenesis
* Dyshormonogenesis
6. Post-partum thyroiditis (hypo-phase)
7. Infiltrative disease:
* Riedel thyroiditis
* Hemochromatosis
* Amyloidosis
### **Secondary (Pituitary)**
* Pituitary tumor or surgery
* Sheehan syndrome
* Empty sella
### **Tertiary (Hypothalamic)**
* Trauma
* Tumors
* Irradiation
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## **4. CLINICAL FEATURES**
### **General**
* Fatigue, lethargy
* Weight gain (mild)
* Cold intolerance
* Depression
* Dry skin
* Hair loss, loss of lateral eyebrows
### **Cardiovascular**
* Bradycardia
* Pericardial effusion
* Diastolic hypertension
* ↑ LDL, ↑ cholesterol
### **Gastrointestinal**
* Constipation
* Decreased appetite
### **Neuromuscular**
* Myalgia, cramps
* Delayed tendon reflex relaxation
* Carpal tunnel syndrome
### **Reproductive**
* Menorrhagia
* Infertility
* ↓ libido
### **Dermatologic**
* Puffy face
* Non-pitting edema (myxedema)
* Dry, cool skin
### **Severe**
* **Myxedema coma** (life-threatening)
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## **5. INVESTIGATIONS**
### **Primary tests**
* **TSH** (elevated in primary)
* **Free T4** (low)
* ± Free T3 (not essential)
### **Autoimmune markers**
* Anti-TPO antibodies (high in Hashimoto)
* Anti-thyroglobulin antibodies
### **Lipid profile** → ↑ cholesterol, ↑ LDL
### **CBC** → normocytic normochromic anemia
### **CMP** → hyponatremia
### **ECG** → bradycardia
### **Ultrasound thyroid** (if goiter or nodules)
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## **6. DIFFERENTIAL DIAGNOSIS**
* Anemia (iron deficiency, B12 deficiency)
* Chronic fatigue syndrome
* Depression
* Heart failure
* PCOS
* Adrenal insufficiency
* Nephrotic syndrome (for edema)
* Myxedema from other causes
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# **7. MANAGEMENT (STEPWISE)**
## **A. General Principles**
* Replace thyroid hormone → **Levothyroxine (LT4)**
* Treat underlying cause
* Monitor TSH every 6–8 weeks
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## **B. LEVOTHYROXINE DETAILS (FULL PHARMACOLOGY)**
### **Indication**
* Primary, secondary, tertiary hypothyroidism
* Goiter management
* Post-thyroidectomy replacement
### **Mechanism of Action**
Synthetic T4 → converted to T3 in tissues → regulates gene transcription, metabolic activity, thermogenesis.
### **Adult Dosing**
* Young, healthy adults: **1.6 mcg/kg/day**
* Age > 60 / cardiac disease: **25–50 mcg/day**, titrate slowly
* Subclinical (TSH 5–10): 25–50 mcg/day (based on indication)
* Pregnancy:
* Increase dose by **30–50% immediately**
* Target TSH:
* 1st trimester: <2.5
* 2nd: <3
* 3rd: <3.5
### **Paediatric Dosing**
* Newborns: **10–15 mcg/kg/day**
* 1–5 yrs: 4–6 mcg/kg/day
* 6–12 yrs: 3–5 mcg/kg/day
* Adolescents: 2–4 mcg/kg/day
### **Pharmacokinetics**
* Absorption: 60–80% (empty stomach)
* Long half-life: ~7 days
* Interfered by calcium, iron, PPIs, soy, antacids
### **Common Adverse Effects** (usually overdose)
* Palpitations
* Heat intolerance
* Anxiety
* Tremor
### **Serious Adverse Effects**
* Atrial fibrillation
* Angina
* Osteoporosis (long-term high doses)
### **Contraindications**
* Uncorrected adrenal insufficiency
* Thyrotoxic crisis (not needed)
* Acute MI (caution)
### **Important Drug Interactions**
* ↓ absorption:
* Iron, calcium, aluminium antacids
* Sucralfate
* PPIs
* Cholestyramine
* ↑ metabolism:
* Rifampicin
* Carbamazepine
* Amiodarone: inhibits T4→T3 conversion
### **Monitoring Parameters**
* TSH every 6–8 weeks after dose change
* Once stable → every 6–12 months
* Lipid profile improvement
* Cardiac symptoms in elderly
### **Patient Counselling**
* Take LT4 **empty stomach**, morning, with water
* Avoid food for 30–60 minutes
* Avoid taking calcium/iron within 4 hours
* Do not switch brands frequently
* Continue lifelong unless reversible cause
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## **C. SPECIAL SITUATIONS**
### **Myxedema Coma (Emergency)**
* IV Levothyroxine 200–400 mcg loading
* IV hydrocortisone 100 mg q8h
* Passive rewarming
* Correct hyponatremia
* Support ventilation
### **Hypothyroidism in Pregnancy**
* Increase LT4 dose by 30–50%
* Monthly TSH monitoring
### **Subclinical Hypothyroidism**
Treat if:
* TSH >10
* Pregnancy or infertility
* Goiter or anti-TPO positive
* Symptomatic patient
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## **8. COMPLICATIONS**
* Hyperlipidemia → CAD
* Infertility
* Heart failure
* Cognitive decline
* Carpal tunnel syndrome
* Myxedema coma (rare but deadly)
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## **9. PREVENTION**
* Adequate dietary iodine (150 mcg/day adults)
* Monitor patients on lithium/amiodarone
* Screen high-risk: pregnancy, autoimmune disease, elderly
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# **SUMMARY FOR FAST REVISION (NEET PG STYLE)**
* **Primary hypo**: ↑TSH, ↓T4
* **Most common cause**: Hashimoto
* **Best test**: TSH
* **Treatment**: Levothyroxine (LT4)
* **Pregnancy**: +30–50% dose
* **Myxedema coma**: Emergency + IV LT4 + steroids
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Below are **35 high-yield, real-world, exam-quality + clinician-style case scenarios of HYPOTHYROIDISM** with **diagnosis, reasoning, management, and patient advice**.
Perfect for **NEET PG**, **ENDO practice**, and **your websites** (ErrorOn Space, RNT, NEETPG).
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## **CASE 1 — Classic Primary Hypothyroidism**
**Presentation:** 32-year-old female, fatigue, weight gain, constipation, dry skin.
**Investigations:** TSH 18 mIU/L, FT4 low. Anti-TPO positive.
**Diagnosis:** Autoimmune (Hashimoto).
**Management:** Levothyroxine 1.6 mcg/kg/day.
**Advice:** Take LT4 empty stomach; lifelong therapy.
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## **CASE 2 — Subclinical Hypothyroidism**
**Presentation:** 40-year-old male, mild lethargy.
**Labs:** TSH 6.5, normal FT4, Anti-TPO positive.
**Diagnosis:** Subclinical hypothyroidism.
**Management:** LT4 25–50 mcg/day (Anti-TPO positive).
**Advice:** Recheck TSH in 6–8 weeks.
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## **CASE 3 — Hypothyroidism Post-Radioiodine**
**Presentation:** 45-year-old woman treated for Graves disease with RAI 1 year ago.
**Labs:** TSH 22, FT4 low.
**Diagnosis:** Iatrogenic hypothyroidism.
**Management:** Start LT4 full dose.
**Advice:** Expect lifelong replacement.
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## **CASE 4 — Post-Thyroidectomy**
**Presentation:** 55-year-old post-total thyroidectomy.
**Diagnosis:** Surgical hypothyroidism.
**Management:** LT4 1.8 mcg/kg/day.
**Advice:** Never stop LT4; monitor TSH.
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## **CASE 5 — Hypothyroidism Misdiagnosed as Depression**
**Presentation:** 29-year-old female labelled as depression.
**Labs:** TSH 15, FT4 low.
**Diagnosis:** Hypothyroidism presenting with depressive symptoms.
**Management:** LT4 therapy.
**Advice:** Mood improves after correction of thyroid levels.
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## **CASE 6 — Hypothyroidism Presenting as Hyperlipidemia**
**Presentation:** 50-year-old with LDL 210 mg/dL.
**Labs:** TSH 28.
**Diagnosis:** Hypothyroidism-induced dyslipidemia.
**Management:** LT4 + repeat lipids after euthyroid achieved.
**Advice:** Statins only if LDL persists post-treatment.
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## **CASE 7 — Myxedema Coma**
**Presentation:** Elderly woman, confusion, hypothermia, bradycardia, hypotension.
**Diagnosis:** Myxedema coma (medical emergency).
**Management:**
* IV Levothyroxine: 200–400 mcg loading
* IV Hydrocortisone: 100 mg q8h
* Warm blankets
* Correct hyponatremia
**Advice:** Close ICU monitoring.
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## **CASE 8 — Pregnancy + Hypothyroidism**
**Presentation:** 28-year-old pregnant (8 weeks) with fatigue.
**Labs:** TSH 6.0 (cutoff <2.5 in 1st trimester).
**Diagnosis:** Maternal hypothyroidism.
**Management:** Increase LT4 dose by **30–50%** immediately.
**Advice:** Monthly TSH; crucial to prevent miscarriage & low IQ.
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## **CASE 9 — Postpartum Thyroiditis (Hypo-phase)**
**Presentation:** 3 months postpartum, fatigue, depression.
**Labs:** TSH 14, FT4 low.
**Diagnosis:** Postpartum thyroiditis (hypo phase).
**Management:** LT4 25–50 mcg/day if symptomatic.
**Advice:** May normalize in 6–12 months.
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## **CASE 10 — Lithium-Induced Hypothyroidism**
**Presentation:** Bipolar patient on lithium.
**Labs:** TSH 20, FT4 low.
**Diagnosis:** Drug-induced hypothyroidism.
**Management:** Continue lithium + start LT4.
**Advice:** Regular thyroid monitoring every 6 months.
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## **CASE 11 — Amiodarone-Induced Hypothyroidism**
**Presentation:** Arrhythmia patient on amiodarone.
**Labs:** TSH 30.
**Diagnosis:** Amiodarone-induced hypothyroidism.
**Management:** LT4; continue amiodarone if essential.
**Advice:** Check TSH every 6 months.
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## **CASE 12 — Congenital Hypothyroidism (Neonate)**
**Presentation:** Prolonged jaundice, hypotonia, large tongue.
**Labs:** TSH high, T4 low.
**Management:** **LT4: 10–15 mcg/kg/day immediately**
**Advice:** Prevents irreversible mental retardation.
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## **CASE 13 — Adolescent Hypothyroidism**
**Presentation:** 14-year-old girl, delayed puberty, weight gain.
**Diagnosis:** Primary hypothyroidism.
**Management:** LT4 2–4 mcg/kg/day.
**Advice:** Growth improves after euthyroid state.
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## **CASE 14 — Elderly Hypothyroidism**
**Presentation:** 72-year-old, fatigue + slowing of activities.
**Management:** LT4 **start 25 mcg/day**
**Advice:** Slow titration to avoid arrhythmias.
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## **CASE 15 — Hypothyroidism Masquerading as Heart Failure**
**Presentation:** Edema, dyspnea, bradycardia.
**Diagnosis:** Hypothyroidism → pericardial effusion.
**Management:** LT4 + follow echo.
**Advice:** Heart function improves after correction.
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## **CASE 16 — Refractory Hypothyroidism**
**Presentation:** LT4 150 mcg but TSH still high.
**Cause:** Poor absorption (PPIs, iron, calcium).
**Management:**
* Take LT4 alone, empty stomach
* Space iron/calcium by 4 hours
**Advice:** Avoid switching brands.
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## **CASE 17 — Hypothyroidism in CKD**
**Presentation:** CKD patient with fatigue.
**Management:** LT4; lower starting dose.
**Advice:** Monitor for fluid retention.
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## **CASE 18 — Hypothyroidism + Infertility**
**Presentation:** 30-year-old woman trying to conceive.
**Labs:** TSH 5.5
**Management:** LT4 to target TSH <2.5
**Advice:** Improves fertility.
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## **CASE 19 — Pituitary Tumor Causing Secondary Hypothyroidism**
**Presentation:** Low TSH + low FT4
**Diagnosis:** Secondary hypothyroidism
**Management:**
* **Rule out adrenal insufficiency FIRST**
* Then start LT4
**Advice:** MRI pituitary needed.
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## **CASE 20 — Hypothyroidism Misdiagnosed as PCOS**
**Presentation:** Irregular menses, weight gain.
**Labs:** TSH high.
**Management:** LT4 normalizes cycles.
**Advice:** Avoid unnecessary PCOS treatment.
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## **CASE 21 — Hypothyroidism + Depression**
**Presentation:** Low mood resistant to antidepressants.
**Labs:** TSH 12
**Management:** LT4
**Advice:** Mood improves in 3–6 weeks.
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## **CASE 22 — Hypothyroidism + Carpal Tunnel**
**Presentation:** Hand tingling.
**Diagnosis:** Hypothyroidism causing median nerve edema.
**Management:** LT4
**Advice:** Splint + thyroid correction resolves it.
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## **CASE 23 — Hypothyroidism in ICU Patient**
**Presentation:** Critically ill patient with low T3.
**Diagnosis:** Consider NTIS vs true hypothyroidism.
**Management:** Treat only if TSH elevated.
**Advice:** Avoid unnecessary LT4.
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## **CASE 24 — Hypothyroidism Triggered by Iodine Deficiency**
**Presentation:** Rural area, goiter.
**Management:** Iodized salt + LT4
**Advice:** Nutrition counselling.
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## **CASE 25 — Severe Constipation From Hypothyroidism**
**Presentation:** Chronic constipation.
**Management:** LT4 + fibre + hydration
**Advice:** Symptoms improve within weeks.
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## **CASE 26 — Hypothyroidism in Obesity**
**Presentation:** BMI 38; expecting weight loss pills.
**Management:** Correct thyroid first
**Advice:** LT4 is **not** for weight loss.
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## **CASE 27 — Hypothyroidism Causing Anemia**
**Presentation:** Normocytic anemia.
**Labs:** TSH high.
**Management:** LT4
**Advice:** Hemoglobin improves with correction.
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## **CASE 28 — Hypothyroidism + Hyponatremia**
**Presentation:** Na = 125 mmol/L
**Cause:** SIADH-like effect of hypothyroidism
**Management:** LT4 correction
**Advice:** Fluids restriction temporarily.
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## **CASE 29 — Hypothyroidism + Elevated CK**
**Presentation:** Muscle pain, CK 950 U/L.
**Diagnosis:** Hypothyroid myopathy
**Management:** LT4
**Advice:** Avoid statins until euthyroid.
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## **CASE 30 — Hypothyroidism + Memory Impairment**
**Presentation:** Forgetfulness
**Management:** Start LT4
**Advice:** Cognitive function improves in months.
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## **CASE 31 — Post-partum Woman Misdiagnosed as Anxiety**
**Presentation:** Fatigue, hair loss, anxiety.
**Labs:** TSH high.
**Management:** LT4
**Advice:** Distinguish from post-partum depression.
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## **CASE 32 — Adolescent with Goiter**
**Presentation:** Painless goiter
**Diagnosis:** Hashimoto
**Management:** LT4 reduces TSH & goiter
**Advice:** Regular follow-ups.
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## **CASE 33 — Subclinical Hypothyroidism + Cardiac Patient**
**Presentation:** TSH 7, stable angina
**Management:** LT4 low dose (12.5–25 mcg)
**Advice:** Slow titration to avoid ischemia.
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## **CASE 34 — Hypothyroidism in a Vegan**
**Presentation:** Taking soy-rich diet
**Issue:** Soy reduces LT4 absorption
**Management:** Increase LT4 dose or adjust timing
**Advice:** Take LT4 4 hours away from soy.
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## **CASE 35 — Hypothyroidism + Chronic Fatigue Syndrome**
**Presentation:** Persistent fatigue
**Labs:** TSH 8
**Management:** LT4
**Advice:** Full recovery may take 6–12 weeks.
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Below are **10 LONG, fully-developed, high-interest, real-world, clinician-level case scenarios** of **Hypothyroidism**, written in a way suitable for:
* **NEET PG / INI-CET**
* **Clinical practice**
* **Your medical education websites (RNT / NEETPG ErrorOn Space)**
* **Long-form teaching content + video scripts**
Each case includes **full presentation → history → examination → investigations → diagnosis → management → counselling**.
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# **CASE 1 — The Businesswoman Who Thought She Had “Burnout”**
### **Presentation**
A 38-year-old corporate manager complains of “burnout,” weight gain despite dieting, and inability to wake up refreshed for 6 months.
### **History**
* Gained 7 kg in 4 months
* Cold intolerance
* Depression-like symptoms
* Heavy menstrual bleeding
* No medications
* Mother has autoimmune disease
### **Examination**
* Puffy face, dry skin
* BMI 29
* Pulse: 58/min
* Delayed ankle jerk relaxation
* Mild diffuse thyroid enlargement
### **Investigations**
* TSH: **28 mIU/L**
* FT4: **low**
* Anti-TPO: **high (650 IU)**
* Lipids: LDL 190 mg/dL
* CBC: normocytic anemia
* USG thyroid: hypoechoic, heterogeneous
### **Diagnosis**
**Hashimoto Hypothyroidism with autoimmune background**
### **Management**
* Start **Levothyroxine 1.6 mcg/kg/day**
* Treat anemia
* Diet counseling
* Repeat TSH in 6–8 weeks
### **Advice**
* LT4 empty stomach
* Mood improves in 3–6 weeks
* Condition is lifelong; excellent prognosis with treatment
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# **CASE 2 — The College Girl With Severe Anxiety Attacks**
### **Presentation**
22-year-old college student with anxiety episodes, fatigue, and poor concentration.
### **History**
* 2 months of anxiety
* Periods irregular
* Gained 4 kg
* Hair fall
* No family history
### **Examination**
* Pulse: 62/min
* Cool extremities
* Dry skin
* Mild goiter
### **Investigations**
* TSH: 9.8
* FT4: low-normal
* Anti-TPO: positive
* Vitamin D: low
* ECG: normal
### **Diagnosis**
**Subclinical hypothyroidism presenting with anxiety**
### **Management**
* Levothyroxine 50 mcg/day
* Vitamin D replacement
* Stress-control strategies
### **Advice**
* Anxiety is thyroid-related, not psychiatric
* TSH target: <3
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# **CASE 3 — Myxedema Coma in Winter**
### **Presentation**
72-year-old woman found unconscious during winter with hypothermia.
### **History**
* Long-standing untreated hypothyroidism
* Recent pneumonia
* Not eating for 2 days
* No meds
### **Examination**
* Temp: 32°C
* BP: 90/60
* Pulse: 40/min
* Hypoventilation
* Generalized swelling
### **Investigations**
* TSH: 58
* FT4: very low
* ABG: CO₂ retention
* Serum sodium: 122
* ECG: low voltage
### **Diagnosis**
**Myxedema coma — life-threatening**
### **Management**
* ICU admission
* **IV Levothyroxine 300 mcg loading**
* **IV hydrocortisone 100 mg q8h**
* Passive rewarming
* Treat pneumonia
### **Advice**
* Lifelong follow-up required
* Educate family on danger signs
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# **CASE 4 — Postpartum Woman Misdiagnosed as Depression**
### **Presentation**
28-year-old mother, 3 months postpartum, complaining of fatigue and low mood.
### **History**
* Feeling always tired
* Weight gain
* Low milk production
* No thyroid history
* Recently had a viral illness postpartum
### **Examination**
* Pulse: 54/min
* Puffy face
* Dry skin
* Thyroid normal
### **Investigations**
* TSH: 32
* FT4: low
* Anti-TPO: positive
### **Diagnosis**
**Postpartum thyroiditis — hypothyroid phase**
### **Management**
* LT4 50 mcg/day
* Support breastfeeding
* Follow-up in 6 weeks
### **Advice**
* May return to normal in 6–12 months
* Watch for transition to hyperthyroid phase later
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# **CASE 5 — Hypothyroidism Presenting as Infertility**
### **Presentation**
34-year-old woman with 2-year infertility.
### **History**
* Irregular cycles
* Fatigue
* Cold intolerance
* Dry skin
* No prior evaluation
### **Examination**
* BMI 31
* Goiter present
* Pulse: 60
### **Investigations**
* TSH: 12
* FT4: low
* Anti-TPO: high
* Prolactin mildly elevated
### **Diagnosis**
**Hypothyroidism causing anovulation & infertility**
### **Management**
* Start LT4, target TSH < 2.5
* Lifestyle changes
* Re-evaluate fertility after 3 months
### **Advice**
* 40–60% regain ovulation naturally
* Continue LT4 throughout pregnancy
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# **CASE 6 — Secondary Hypothyroidism from Pituitary Tumor**
### **Presentation**
48-year-old male with fatigue, decreased libido, and headaches.
### **History**
* Progressive vision blurring
* Weight gain
* Erectile dysfunction
### **Examination**
* Bitemporal hemianopia
* Decreased body hair
* No goiter
### **Investigations**
* TSH: **low/normal**
* FT4: **low**
* Cortisol: low
* MRI brain: pituitary macroadenoma
### **Diagnosis**
**Secondary hypothyroidism due to pituitary adenoma**
### **Management**
* **Start hydrocortisone BEFORE LT4**
* Then start LT4 replacement
* Neurosurgical consult
### **Advice**
* Regular MRI follow-up
* Counselling for hormone replacement lifelong
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# **CASE 7 — Chronic Kidney Disease Patient With Sudden Decline**
### **Presentation**
60-year-old CKD stage 4 patient with worsening fatigue & breathlessness.
### **History**
* Reduced appetite
* Taking iron supplements + calcium
* On PPI for GERD
### **Examination**
* Pale
* Pulse 58
* Mild edema
### **Investigations**
* TSH: 25
* FT4: low
* Calcium supplement + PPI interfering with LT4
### **Diagnosis**
**Hypothyroidism from poor absorption of LT4 in CKD**
### **Management**
* Adjust LT4 timing
* Space calcium/iron by 4 hours
* Consider switching PPI
### **Advice**
* LT4 must be taken **alone** on empty stomach
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# **CASE 8 — Hypothyroidism Masquerading as Heart Disease**
### **Presentation**
52-year-old woman with chest heaviness and poor exercise tolerance.
### **History**
* No cardiac risk factors
* Fatigue, constipation
* Weight gain
* No known thyroid disorder
### **Examination**
* Pulse 56
* Pericardial rub absent
* Delayed reflexes
### **Investigations**
* TSH: 40
* FT4: very low
* Echocardiography: mild pericardial effusion
### **Diagnosis**
**Hypothyroidism causing pericardial effusion and cardiac symptoms**
### **Management**
* LT4 high-dose replacement
* Monitor effusion
* No need for pericardiocentesis unless tamponade
### **Advice**
* Effusion resolves within months
* Do not stop medications abruptly
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# **CASE 9 — Teenager With Severe Obesity but Hidden Hypothyroidism**
### **Presentation**
16-year-old girl brought for obesity treatment.
### **History**
* Gained 12 kg in a year
* Poor school performance
* Irregular periods
* Constipation
* Hair fall
### **Examination**
* BMI 33
* Dry, cool skin
* Thyroid enlarged
### **Investigations**
* TSH: 16
* FT4: low
* Anti-TPO: high
### **Diagnosis**
**Hypothyroidism contributing to adolescent obesity**
### **Management**
* LT4 weight-adjusted dosing
* Diet + exercise plan
* Menstrual cycle monitoring
### **Advice**
* Obesity will reduce slowly
* Thyroid correction improves school performance
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# **CASE 10 — Elderly Man With Repeated Falls**
### **Presentation**
70-year-old male brought after recurrent falls & confusion.
### **History**
* Slow movements
* Slurred speech
* On beta-blockers for hypertension
### **Examination**
* Bradycardia (50/min)
* Dry skin
* Mild pitting edema
* Cognitive slowing
### **Investigations**
* TSH: 35
* FT4: very low
* Sodium: 126 (hyponatremia)
### **Diagnosis**
**Severe hypothyroidism causing hyponatremia & cognitive dysfunction**
### **Management**
* LT4 low dose (due to age + heart disease)
* Slow titration
* Fluid restriction for hyponatremia
### **Advice**
* Fall-prevention strategies
* Cognition improves as thyroid normalizes
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