When to intubate in GCS?

GCS ≤ 8 requires intubation for airway protection. The patient cannot protect their own airway at this level of consciousness. Motor score is the most prognostically important component.

What is the best initial fluid for sepsis resuscitation?

Lactated Ringer's (LR) is the preferred resuscitation fluid. The SMART trial (2018) showed balanced crystalloids reduced death, new renal failure, and persistent renal dysfunction compared to normal saline.

When to start vasopressors in septic shock?

Start norepinephrine (first-line vasopressor) if MAP remains < 65 mmHg after initial 30 mL/kg crystalloid resuscitation, or earlier if patient is profoundly hypotensive. Do not delay pressors to complete full fluid resuscitation.

Why can serum uric acid be normal during acute gout?

During acute inflammation, IL-6 increases renal urate excretion and redistributes urate from plasma to tissues. Up to 40% of acute gout flares have normal serum uric acid. Joint aspiration with polarized microscopy is needed for definitive diagnosis.

How do you distinguish lupus flare from infection in SLE?

Key clues: CRP is low/normal in flare but elevated in infection. Complement (C3/C4) drops in flare but is normal/elevated in infection. Procalcitonin is elevated in bacterial infection but normal in flare. Anti-dsDNA rises in flare, stable in infection.

What is the difference between DKA and HHS?

DKA features acidosis (pH 600), hyperosmolality (> 320), and minimal ketosis -typically in Type 2 DM. DKA requires insulin drip; HHS requires aggressive fluid resuscitation first.

When to give tPA in acute ischemic stroke?

IV alteplase (tPA) can be given within 4.5 hours of last known well time in eligible patients. CT head must rule out hemorrhage first. For large vessel occlusion, mechanical thrombectomy can be performed up to 24 hours with favorable imaging.

What antibiotics for community-acquired pneumonia?

Inpatient non-ICU: ceftriaxone + azithromycin. ICU: ceftriaxone + azithromycin (add vancomycin if MRSA risk). Outpatient healthy: amoxicillin. Outpatient with comorbidities: augmentin + azithromycin or respiratory fluoroquinolone. Duration: 5 days if clinically stable for 48 hours.

How to interpret iron studies?

Iron deficiency: low ferritin (< 30), high TIBC, low iron, low transferrin saturation (< 20%). Anemia of chronic disease: normal/high ferritin (acute phase reactant), low TIBC, low iron. A ferritin of 50-100 in an inflamed patient may still represent iron deficiency.

What is the correction rate for hyponatremia?

Correct sodium no more than 8 mEq/L in 24 hours to avoid osmotic demyelination syndrome (ODS). For symptomatic severe hyponatremia with seizures, give 3% hypertonic saline 100-150 mL bolus over 10-20 minutes. If overcorrected, use D5W + DDAVP rescue protocol.

When to start antibiotics in meningitis?

Within 30-60 minutes. Do NOT delay antibiotics for LP or CT. Draw blood cultures, start empiric antibiotics (vancomycin + ceftriaxone ± ampicillin if > 50 or immunocompromised), then perform LP when possible. Dexamethasone should be given before or with the first antibiotic dose.

DOACs vs warfarin in antiphospholipid syndrome?

DOACs are contraindicated in APS. The TRAPS trial (2018) showed rivaroxaban was inferior to warfarin with more thrombotic events in triple-positive APS patients. Warfarin with INR target 2-3 is the standard for APS, indefinitely.

How to manage scleroderma renal crisis?

ACE inhibitors (captopril) are life-saving -start immediately and titrate aggressively. Do NOT hold for rising creatinine. Steroids > 15 mg prednisone per day precipitate scleroderma renal crisis. ARBs are NOT a substitute -evidence is only for ACEi.

What are the 4 pillars of heart failure treatment?

Guideline-directed medical therapy (GDMT) for HFrEF: (1) ARNI or ACEi/ARB, (2) beta-blocker (carvedilol, metoprolol succinate, or bisoprolol), (3) MRA (spironolactone or eplerenone), (4) SGLT2 inhibitor (dapagliflozin or empagliflozin). All four should be initiated and titrated to target doses.

RoundsRx

Dashboard

Overview

Recent

Rotations

Quick Reference

Antibiotic Guide Analgesia Guide Sedation Guide Bowel Regimen Electrolyte Replacement Pain Management & Conversions Drug Interactions Anticoag Reversal IV Fluid Guide Inotropes Guide Vasopressors Insulin Guide Code Blue & Rapid Response Procedures Guide ECG Interpretation Lab Interpretation Radiology Quick Ref GCS Pocket Card Admission Orders & I-PASS Landmark Trials

Tools

💎 Clinical Pearls 🧠 Pimp Me Quiz 🧮 Clinical Calculators 📰 What's New 🎓 Intern Survival Guide ✅ Rounding Checklists 🩺 Procedure Guides ⚡ Electrolyte Replacement 💧 IV Fluids Guide 🩸 Transfusion Guide 💓 ECG Pattern Guide 🧪 Lab Interpretation Guide 📱 QR Poster 🔗 Resources 🎙️ Channels & Podcasts 🎮 Medical Games 🏛️ Famous Cases 🎬 Media Library

ℹ️ About

Available offline

Endocrine

Hypothyroidism

Most common endocrine disorder. Hashimoto's thyroiditis is the #1 cause in iodine-sufficient areas. Levothyroxine replacement -simple in concept, nuanced in practice.

🔍 Overview

Overview

Hypothyroidism = insufficient thyroid hormone production. Primary (> 95%): thyroid gland failure -TSH high, FT4 low. Central (< 5%): pituitary or hypothalamic disease -TSH low/normal, FT4 low. Hashimoto's thyroiditis (chronic autoimmune) is the #1 cause in iodine-sufficient countries. Other causes: post-RAI, post-thyroidectomy, post-radiation, medications (amiodarone, lithium, checkpoint inhibitors), iodine deficiency (worldwide), infiltrative (sarcoidosis, hemochromatosis). Prevalence: 5-10% (overt + subclinical). Subclinical hypothyroidism: TSH elevated (4.5-10), FT4 normal. Treatment controversial -treat if: TSH > 10, symptoms, pregnancy/planning pregnancy, positive TPO antibodies with TSH > 7. Symptoms: fatigue, cold intolerance, weight gain, constipation, dry skin, hair loss, menorrhagia, depression, myalgias, delayed DTRs.

🧪 Workup

Workup

TSH -most sensitive test. Elevated in primary hypothyroidism. Normal/low in central hypothyroidism (misleading -always check FT4 if clinical suspicion).
Free T4 -low confirms hypothyroidism. TSH high + FT4 low = primary overt hypothyroidism. TSH high + FT4 normal = subclinical.
TPO antibodies (anti-thyroid peroxidase) -positive in Hashimoto's (~95%). Useful for: (1) confirming etiology, (2) predicting progression from subclinical → overt, (3) informs treatment decisions in subclinical hypothyroidism.
Anti-thyroglobulin antibodies -positive in ~60% of Hashimoto's. Less specific than TPO.
Lipid panel -hypothyroidism causes hyperlipidemia (elevated LDL). May normalize with treatment. Don't start statins until euthyroid.
CBC -normocytic or macrocytic anemia is common
BMP -hyponatremia (impaired free water excretion), elevated Cr (decreased renal perfusion)
CK -elevated from hypothyroid myopathy (can be markedly elevated, mimicking rhabdomyolysis)
If central hypothyroidism suspected: check FT4 (not just TSH), pituitary MRI, assess other pituitary axes (ACTH/cortisol, FSH/LH, GH, prolactin). Must rule out adrenal insufficiency before starting T4 (same principle as myxedema coma).

🚨 Management

Management

Levothyroxine (T4): Standard replacement. Full dose: 1.6 mcg/kg/day. Start lower in elderly or cardiac patients: 12.5-25 mcg daily → increase by 12.5-25 mcg q6-8 weeks.
How to take: On empty stomach, 30-60 min before breakfast (or at bedtime, ≥ 3h after last meal). Separate from calcium, iron, PPIs, soy, coffee by ≥ 4 hours (all impair absorption).
Dose adjustments:
- Check TSH at 6-8 weeks (TSH has a long half-life -don't recheck sooner).
- Target TSH 0.5-2.5 mIU/L for most adults. Elderly (> 70): target 3-6 (higher TSH is protective, over-replacement → AF + osteoporosis).
- Pregnancy: target TSH < 2.5 in 1st trimester. Levothyroxine dose typically increases 25-50% during pregnancy. ATA, 2017

Monitoring

💊 Medications

Medications

Drug	Dose	Route	Notes
Levothyroxine (T4)	1.6 mcg/kg/day (full dose); start 25-50 mcg in elderly	PO	Standard of care. Empty stomach, 30-60 min before breakfast. Separate from Ca, Fe, PPI by 4h. Half-life 7 days → steady state in 6 wk. ATA, 2014
Liothyronine (T3)	5-25 mcg daily (divided BID-TID)	PO	NOT routine. Short half-life → TID dosing. Consider only if persistent symptoms on adequate T4 with normal TSH. Variable absorption.
IV levothyroxine	50-100% of oral dose	IV	For patients who cannot take PO (ICU, post-surgical). 100% bioavailable vs ~70% PO. For myxedema coma: loading dose 200-400 mcg.

🏥 Rounds

Pimp Questions

❓ Why must you wait 6-8 weeks to recheck TSH after a levothyroxine dose change?

Levothyroxine has a half-life of 7 days. It takes approximately 5 half-lives (35 days) to reach steady state. Checking TSH sooner gives a misleading result because the new dose hasn't equilibrated yet. If you increase dose and recheck at 2 weeks, the TSH may still appear elevated → you increase again → overcorrection → iatrogenic hyperthyroidism.

❓ What medications interfere with levothyroxine absorption?

Must separate by ≥ 4 hours: (1) Calcium (supplements and antacids), (2) Iron, (3) PPIs/H2 blockers (need gastric acid for T4 absorption), (4) Soy products, (5) Cholestyramine (binds T4 in gut), (6) Sucralfate, (7) Coffee (reduces absorption by ~30%). Practical advice: take levothyroxine first thing in morning with water only, eat/take other meds ≥ 30-60 min later.

❓ When do you treat subclinical hypothyroidism?

Always treat: TSH > 10, pregnant or planning pregnancy, goiter. Strongly consider treating: TSH 7-10 with positive TPO antibodies (high progression rate to overt hypothyroidism, ~5% per year), symptoms suggestive of hypothyroidism, hyperlipidemia that may improve with treatment. Observe: TSH 4.5-7 without symptoms or risk factors. Elderly > 70: higher TSH may be physiologically normal -treating can cause harm (AF, fractures).

❓ Why should levothyroxine dose be increased in pregnancy?

Pregnancy increases T4 demand by 25-50% due to: (1) increased TBG (estrogen-mediated → more T4 bound, less free), (2) increased plasma volume (dilution), (3) placental deiodinase (degrades T4), (4) fetal thyroid doesn't function until week 12 -fetus depends entirely on maternal T4 for neurodevelopment. Maternal hypothyroidism → lower fetal IQ, neurodevelopmental delay. Increase dose empirically by 2 extra tablets per week when pregnancy confirmed. ATA, 2017

❓ What is the #1 cause of persistently elevated TSH in a patient on levothyroxine?

Non-compliance. Before increasing the dose, always ask: (1) Are you taking it daily? (2) On empty stomach, 30-60 min before eating? (3) Are you taking calcium, iron, or PPIs near the dose? (4) Any new medications? A common pattern: patient takes T4 intermittently, TSH remains elevated → dose is increased → patient takes it consistently for a few days before the lab → TSH normalizes temporarily → cycle repeats.

Clinical Examples

📋 Case 1, New Diagnosis of Hashimoto's Hypothyroidism

Patient: 38F with fatigue, weight gain (12 lb/6 months), constipation, cold intolerance, and menorrhagia. TSH 62 mIU/L, FT4 0.3 ng/dL. TPO Ab 580 IU/mL. No goiter.

Key findings: Overt primary hypothyroidism (elevated TSH + low FT4). Hashimoto thyroiditis confirmed by strongly positive TPO antibodies. Symptomatic.

Management:

Levothyroxine 1.6 mcg/kg/day (full replacement dose in young, healthy patient), ~88 mcg daily
Take on empty stomach, 30-60 min before breakfast. Avoid calcium, iron, PPI within 4 hours
Recheck TSH in 6-8 weeks (steady state requires 5-6 half-lives; T4 t½ = 7 days)
Goal TSH 0.5-2.5 mIU/L (lower half of normal range for symptomatic patients)
Screen for associated autoimmune conditions: celiac (10% co-occurrence), B12 deficiency, adrenal insufficiency

Teaching point: In young, healthy patients, start full replacement dose immediately. In elderly or cardiac patients, start low (25-50 mcg) and titrate slowly, rapid correction can precipitate angina or arrhythmia.

📋 Case 2, Hypothyroidism in Pregnancy

Patient: 32F with known Hashimoto's on levothyroxine 75 mcg daily. Newly pregnant (6 weeks). Pre-pregnancy TSH 1.8. Current TSH 4.2, FT4 0.8 ng/dL.

Key findings: TSH above pregnancy target (< 2.5 in first trimester per ATA 2017). Fetal thyroid doesn't function until week 12, fetus depends entirely on maternal T4 for neurodevelopment.

Management:

Increase levothyroxine by ~25-30%: add 2 extra tablets per week (75 mcg × 9/week instead of 7) ATA, 2017
Target TSH < 2.5 mIU/L in first trimester, < 3.0 in second/third trimester
Recheck TSH every 4 weeks through mid-pregnancy, then once at 30 weeks
Maternal hypothyroidism → lower fetal IQ and neurodevelopmental delay
Postpartum: return to pre-pregnancy dose, recheck TSH at 6 weeks postpartum

Teaching point: Pregnancy increases T4 demand by 25-50% due to increased TBG, plasma volume expansion, and placental deiodinase. The "2 extra tablets per week" rule is a practical way to increase dose ~30% immediately.

📋 Case 3, Myxedema Coma

Patient: 72F brought by EMS. Found unresponsive at home. Temp 33.2°C, HR 42, BP 82/50, RR 8. Known hypothyroidism, ran out of levothyroxine 3 months ago. Na 118, glucose 48.

Key findings: Myxedema coma: hypothermia + bradycardia + AMS + hypotension in the setting of severe hypothyroidism. Precipitated by medication non-compliance. Mortality 30-60%.

Management:

IV levothyroxine 200-400 mcg loading dose → 1.6 mcg/kg/day IV (gut absorption unreliable in critical illness)
Stress-dose hydrocortisone 100 mg IV q8h (must rule out concurrent adrenal insufficiency before giving T4, T4 increases cortisol clearance)
Passive rewarming only (active warming → vasodilation → cardiovascular collapse)
D50 for hypoglycemia, hypertonic saline only if Na < 120 with seizures
ICU admission, intubate if GCS ≤ 8, avoid sedatives (prolonged metabolism)

Teaching point: Always give stress-dose steroids BEFORE or WITH IV levothyroxine in myxedema coma. If undiagnosed adrenal insufficiency coexists (Schmidt syndrome), T4 alone can precipitate adrenal crisis.

Sample Presentation

Mrs. Johnson is a 45-year-old woman with 6 months of fatigue, 10 lb weight gain, constipation, cold intolerance, and hair thinning. PMH: nothing. No medications. Exam: dry skin, periorbital puffiness, bradycardia (HR 56), delayed DTR relaxation. No goiter. Labs: TSH 48 mIU/L (elevated), Free T4 0.4 ng/dL (low), TPO Ab 420 IU/mL (strongly positive).

Key Points: Classic overt primary hypothyroidism from Hashimoto's thyroiditis (positive TPO antibodies). Start levothyroxine ~100 mcg daily (estimated 1.6 × 65 kg). Fasting, 30-60 min before breakfast. Recheck TSH in 6-8 weeks. Target TSH 0.5-2.5. Also check lipids (likely elevated -will improve with treatment).

TSH at 6-8 weeks after any dose change -do NOT recheck sooner (TSH equilibration takes 4-6 weeks). Adjust by 12.5-25 mcg increments.
Annual TSH once stable on appropriate dose
Pregnancy: TSH monthly through first trimester, then q4-6 weeks. Increase dose 25-50% as early as 4-6 weeks gestation. ATA, 2017
Central hypothyroidism: Monitor Free T4 (NOT TSH -TSH is unreliable when the pituitary is the problem). Target FT4 in upper half of reference range.
Elderly (> 70): Target TSH 3-6. Do NOT over-replace -subclinical hyperthyroidism from excess T4 → AF, osteoporosis, fractures.
Drug interactions: Reassess dose when starting/stopping calcium, iron, PPIs, estrogen (increases TBG → need more T4), phenytoin/carbamazepine (increase T4 metabolism).
Lipid panel -recheck 3-6 months after achieving euthyroidism (hyperlipidemia often normalizes).

Monitoring

📋 Summary

Summary

Diagnosis

TSH high + FT4 low = primary overt. TSH high + FT4 normal = subclinical. Check TPO Ab.

Treatment

Levothyroxine 1.6 mcg/kg/day. Empty stomach, 30-60 min before food. Separate Ca, Fe, PPI by 4h.

Monitoring

TSH at 6-8 weeks after dose change. Target 0.5-2.5 (elderly: 3-6). Annual once stable.

Subclinical

Treat if: TSH > 10, pregnant, goiter, symptoms + TPO positive, TSH 7-10 + TPO positive.

Pregnancy

Increase dose 25-50% early. Target TSH < 2.5 first trimester. Monthly TFTs.

Pearl

#1 cause of refractory elevated TSH = non-compliance. Central hypothyroidism: monitor FT4, not TSH.

📄 One Pager

One-Pager

Hypothyroidism

Simple drug, nuanced dosing

Levothyroxine Rules

1.6 mcg/kg/day. Empty stomach, 30-60 min before food. Separate Ca/Fe/PPI by 4h. Start low in elderly/cardiac (25 mcg). Recheck TSH at 6-8 weeks. Target 0.5-2.5.

Subclinical Decision

TSH > 10 → treat. TSH 7-10 + TPO+ → treat. Pregnant → treat (target < 2.5). Elderly → often observe (higher TSH may be normal).

Trials

ATA Hypothyroidism Guidelines 2014 · ATA Thyroid in Pregnancy 2017