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.

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EmergentEndocrinology

Hypercalcemia

"Stones, bones, groans, thrones, and psychiatric overtones." Corrected Ca > 10.5 mg/dL. 90% caused by primary hyperparathyroidism or malignancy. Aggressive IVF is the first treatment for everything -then target the cause.

🔍 Overview

Severity

Level	Corrected Ca	Symptoms
Mild	10.5–12 mg/dL	Often asymptomatic. Fatigue, constipation.
Moderate	12–14 mg/dL	Polyuria, polydipsia, nausea, constipation, confusion, short QT on ECG.
Severe (hypercalcemic crisis)	> 14 mg/dL	AMS, stupor, coma, cardiac arrhythmias (short QT → Osborn waves → cardiac arrest), AKI, pancreatitis.

Always correct for albumin: Corrected Ca = measured Ca + 0.8 × (4.0 − albumin). Or check ionized calcium (more accurate, especially in ICU patients).

Differential -The Two Big Ones

Cause	% of Cases	PTH	Key Features
Primary hyperparathyroidism	~55% (most common overall, #1 outpatient cause)	↑ or inappropriately normal	Usually mild, chronic. Single adenoma (~85%). ↑ Ca, ↓ PO₄, ↑ urine Ca. Stones, osteoporosis.
Malignancy	~35% (#1 inpatient cause)	↓ (suppressed)	Usually severe, acute onset. Mechanisms: PTHrP secretion (squamous cell, RCC, breast → humoral hypercalcemia of malignancy), osteolytic metastases (breast, myeloma), calcitriol production (lymphoma).
Other (~10%)		Variable	Granulomatous disease (sarcoid → ↑ calcitriol), thiazides, lithium, vitamin D intoxication, milk-alkali syndrome, immobilization, thyrotoxicosis, Addison disease.

First lab after finding hypercalcemia: PTH. PTH high or normal → primary hyperparathyroidism. PTH low → malignancy or other cause → check PTHrP, vitamin D levels (25-OH and 1,25-OH), SPEP/UPEP.

🥛 Milk-Alkali Syndrome

Classic triad: hypercalcemia + metabolic alkalosis + AKI from excess calcium-containing alkali ingestion. Third most common cause of hypercalcemia in hospitalized patients (after malignancy and primary hyperparathyroidism), and easy to miss because patients describe their calcium carbonate as "antacids" or "Tums" rather than calcium.

Modern setup

Elderly woman taking calcium carbonate (Tums, OsCal, Caltrate) for osteoporosis or GERD, often > 5 g/day elemental calcium. Co-factors that tip her over: thiazide (reduces Ca excretion), volume depletion (NSAIDs, loop diuretics, GI loss), CKD, vitamin D supplementation. Modern incidence rose with widespread OTC calcium use; the historical 1920s "milk + bicarbonate for peptic ulcers" recipe is mostly extinct.

Mechanism (vicious cycle)

High oral Ca and alkali load → mild hypercalcemia + alkalosis.
Hypercalcemia causes renal vasoconstriction and nephrogenic DI → volume depletion → AKI.
AKI prevents the kidney from excreting the alkali load → alkalosis worsens.
Alkalosis further reduces urinary Ca excretion → hypercalcemia worsens.
Loop continues until the calcium source is removed.

Distinguishing labs (PTH suppressed)

Lab	Milk-alkali	vs Primary HPT	vs Malignancy
PTH	Low (suppressed by hyperCa)	High or inappropriately normal	Low (suppressed)
PTHrP	Normal	Normal	Often high (humoral hyperCa of malignancy)
Phosphate	Normal to high	Low (PTH wastes PO₄)	Variable
HCO₃^-	Elevated (metabolic alkalosis)	Normal or mildly low (hyperchloremic acidosis)	Normal
Creatinine	Elevated (AKI is part of the triad)	Often normal	Variable
25-OH / 1,25-OH vit D	Normal (unless coingested)	Variable	1,25 elevated in lymphoma and granulomatous disease

Treatment

Stop the calcium and alkali source immediately. Most cases resolve in 2–7 days.
IV NS 200–500 mL/hr to restore volume and enhance Ca excretion.
Avoid bisphosphonates in most cases. Bone turnover is already suppressed (no osteoclast-driven hyperCa to block), and there is real risk of rebound hypocalcemia once renal Ca handling recovers. Reserve for severe or refractory hypercalcemia.
Hold thiazides (reduce Ca excretion) and any vitamin D supplements.
Dialysis only if severe AKI with refractory hypercalcemia.
Counsel patient and family on safe calcium dosing (target < 1500 mg/day elemental Ca, with food, and separated from PPI).

Boards bait: Elderly woman, calcium carbonate for osteoporosis or "indigestion," now with confusion and AKI. PTH suppressed, phosphate normal-to-high, HCO₃^- elevated. Don't reach for bisphosphonates. Stop the Tums.

🚨 Management

Acute Hypercalcemia Treatment

Step	Drug	Dose	Onset	Notes
1. Volume	IV NS FIRST	200–500 mL/hr (aggressive -these patients are volume-depleted from hypercalcemia-induced nephrogenic DI)	Hours	Always start here. Volume expansion enhances renal Ca excretion. Target UOP 200–300 mL/hr. Most patients need 3–6 L in first 24h.
2. Calcitonin	Calcitonin (Miacalcin)	4 IU/kg SC/IM q12h	4–6 hours	Fastest onset. Inhibits osteoclasts + enhances renal Ca excretion. Effect is modest (↓ Ca by 1–2 mg/dL) and tachyphylaxis within 48h (receptors downregulate). Bridge to bisphosphonate.
3. Bisphosphonate	Zoledronic acid (Zometa) MOST EFFECTIVE	4 mg IV over 15 min	2–4 days	Potent osteoclast inhibitor. Best for malignancy-associated hypercalcemia. Effect lasts 2–4 weeks. Nephrotoxic -hold if Cr > 4.5. Alternative: pamidronate 60–90 mg IV over 2–4h.
4. Denosumab	Denosumab (Xgeva)	120 mg SC	4–10 days	RANKL inhibitor. Use if bisphosphonate-refractory or CKD (not renally cleared). Risk: severe rebound hypercalcemia when stopped.
Steroids	Hydrocortisone (Solu-Cortef) 200 mg IV/day	As needed	Days	Specific indications: granulomatous disease (sarcoid → steroids ↓ calcitriol production), lymphoma, vitamin D intoxication, myeloma. Ineffective for PTH-mediated or most solid tumor hypercalcemia.
Dialysis	Hemodialysis with low-Ca bath	Emergent	Immediate	Last resort for severe (> 18 mg/dL), symptomatic, refractory, or with AKI preventing bisphosphonate use.

Furosemide for hypercalcemia is largely obsolete. Old teaching was "saline + Lasix." Current evidence: loop diuretics only help if the patient is volume-overlo

🧪 Workup

Workup

PTH -the single most important test. Elevated/inappropriately normal = PTH-mediated (primary hyperparathyroidism 90%). Suppressed = PTH-independent (malignancy, granulomatous, vitamin D).
PTHrP -if PTH suppressed. Humoral hypercalcemia of malignancy (squamous cell lung, renal, breast). Elevated in ~80% of malignancy-associated hypercalcemia.
25-OH vitamin D -exogenous vitamin D toxicity
1,25-dihydroxy vitamin D -elevated in granulomatous disease (sarcoidosis, TB, histoplasmosis, lymphoma) -macrophage 1α-hydroxylase activity. Normal PTH, suppressed PTHrP.
SPEP/UPEP + free light chains -multiple myeloma (osteolytic lesions → calcium release). Must check in unexplained hypercalcemia, especially with bone pain + anemia + renal failure.
Corrected calcium = measured Ca + 0.8 × (4 − albumin). Or use ionized calcium (more accurate, not affected by albumin).
ECG -shortened QT interval. Severe: Osborn waves, bradycardia, heart block.
Cr + BUN -hypercalcemia causes nephrogenic DI → dehydration → prerenal AKI (most patients are significantly volume-depleted)
Phosphorus -low in hyperPTH (PTH causes phosphaturia). High in vitamin D toxicity, granulomatous disease, tumor lysis.

💊 Medications

Medications

Drug	Dose	Route	Notes
Normal saline	200-300 mL/hr	IV	FIRST and most important step. Most patients 3-6L depleted from hypercalcemia-induced nephrogenic DI. Restores GFR → renal calcium excretion.
Calcitonin	Endocrine Society, 2014 4 IU/kg IM/SQ q12h	IM/SQ	Fast onset (4-6h). Bridges to bisphosphonate effect. Modest drop (~1-2 mg/dL). Tachyphylaxis at 48h -stop after 2 days.
Zoledronic acid	Zoledronic Acid Hypercalcemia Trial, 2001 4 mg IV over 15 min	IV	Most potent long-term treatment. Onset 2-4 days, peak 4-7 days, lasts weeks. Avoid if CrCl < 35 (use denosumab instead). Monitor for osteonecrosis of jaw (rare).
Denosumab	Denosumab Hypercalcemia Trial, 2014 120 mg SQ	SQ	RANKL inhibitor. Use if renal impairment (not renally cleared) or bisphosphonate failure. Risk of severe rebound hypercalcemia if stopped.
Prednisone	20-40 mg daily	PO	Granulomatous disease and lymphoma ONLY. Blocks 1α-hydroxylase in macrophages. NOT effective for PTH-mediated or PTHrP-mediated.
Cinacalcet	30 mg BID	PO	Calcimimetic for primary hyperPTH (if not surgical candidate). Also parathyroid carcinoma. Lowers PTH → lowers Ca.
Furosemide (Lasix)	20-40 mg IV PRN	IV	ONLY after adequate hydration. Calciuresis. Do NOT give to dehydrated patient -worsens hypercalcemia.

📋 On Rounds

How do you distinguish hyperparathyroidism from malignancy as the cause?

PTH level. In primary hyperparathyroidism, PTH is elevated or inappropriately normal (should be suppressed by high calcium but isn't -the parathyroid adenoma is autonomously producing PTH). In malignancy, PTH is suppressed (low) because the hypercalcemia is driven by PTHrP, osteolytic metastases, or calcitriol -all of which suppress normal PTH via negative feedback.

Why does calcitonin lose effectiveness after 48 hours?

Tachyphylaxis from receptor downregulation. Calcitonin binds osteoclast calcitonin receptors, inhibiting bone resorption. With sustained exposure (> 48h), osteoclasts internalize and downregulate their calcitonin receptors -they become resistant to the drug. The clinical effect fades and calcium starts rising again. This is why calcitonin is a bridge agent -its fast onset (4–6h)

Why is furosemide no longer recommended for hypercalcemia treatment?

Old teaching: "NS + Lasix for hypercalcemia" -the idea was furosemide blocks calcium reabsorption in the Loop of Henle (calciuresis). Current evidence: furosemide is NOT recommended unless the patient is volume overloaded. Reasons: (1) Most hypercalcemia patients are severely volume depleted (hypercalcemia → nephrogenic DI → polyuria → dehydration). Giving furosemide before adequate volume repletion worsens dehydration → worsens hypercalcemia.

What is the approach to determining the etiology of hypercalcemia?

PTH is the branch point. Check PTH first. PTH elevated (or inappropriately normal): primary hyperparathyroidism (#1 cause of hypercalcemia in outpatients). Rarely: familial hypocalciuric hypercalcemia (FHH -check 24h urine calcium: FHH has low urine Ca, PHPT has high urine Ca), lithium-induced, parathyroid carcinoma. PTH suppressed (< 20): non-PTH-mediated.

What is the single most important test in the workup of hypercalcemia?

PTH. It's the diagnostic branch point. Elevated/normal PTH = PTH-mediated (90% primary hyperparathyroidism). Suppressed PTH = malignancy, granulomatous disease, or vitamin D toxicity.

Why should you NOT give furosemide as initial treatment for hypercalcemia?

Most patients are severely dehydrated from hypercalcemia-induced nephrogenic diabetes insipidus. Furosemide in a dehydrated patient worsens volume depletion and hypercalcemia. Rehydrate with NS first, then furosemide only if volume-overloaded.

A patient with sarcoidosis has hypercalcemia. Which medication treats it and why?

Prednisone -sarcoid macrophages express 1α-hydroxylase that converts 25-OH vitamin D to active 1,25-dihydroxy vitamin D. Steroids suppress this enzyme. Bisphosphonates are less effective because the mechanism is vitamin D-mediated, not bone resorption.

Why does calcitonin have tachyphylaxis at 48 hours?

Calcitonin receptors on osteoclasts become downregulated after 48h of continuous exposure. The Ca-lowering effect wanes. It's used only as a bridge while waiting for zoledronic acid to take effect (onset 2-4 days).

📣 Sample Presentation

One-Liner

"Mrs. Taylor is a 72-year-old with metastatic breast cancer presenting with confusion, constipation, and polyuria. Ca²⁺ 14.8 (corrected for albumin). PTH suppressed at 8. PTHrP pending."

Key Points to Cover on Rounds

Hypercalcemia of malignancy (PTH suppressed → not primary hyperparathyroidism). Most likely humoral hypercalcemia (PTHrP secretion from breast cancer). Treatment initiated: (1) NS at 250 mL/hr (volume expansion -first priority), (2) calcitonin 4 IU/kg IM q12h (fast onset, bridges to zoledronic acid, tachyphylaxis at 48h), (3) zoledronic acid 4 mg IV over 15 min (most effective long-term, onset 2-4 days). No furosemide unless volume overloaded. Ca trending 14.8→13.2→11.4 over 48h. Plan: oncology for disease-directed therapy, repeat Ca in 48h, denosumab if bisphosphonate fails.

Monitoring

Ionized calcium q6-12h during active treatment (more accurate than corrected Ca in critical illness, hypoalbuminemia, acid-base disorders)
BMP q12-24h -Cr (renal function during aggressive hydration), K⁺, Mg²⁺ (calcitonin can cause hypokalemia/hypomagnesemia)
Urine output q1-4h during initial hydration -target ≥ 100-150 mL/hr. Hypercalcemia causes nephrogenic DI → patients are severely volume-depleted
ECG -short QT interval, Osborn waves, bradycardia at very high levels. Monitor for QTc normalization
Repeat Ca²⁺ at 48h after zoledronic acid -onset 2-4 days, peak effect 4-7 days. Don't re-dose before day 7.
Phosphate -bisphosphonates can cause hypophosphatemia
Mental status -confusion, lethargy correlate with severity ("bones, stones, groans, psychiatric overtones")
Daily volume status -aggressive IVF can cause overload in CHF/CKD patients

⚡ Summary

Summary

Branch Point

Check PTH first. Elevated → primary hyperparathyroidism. Suppressed → malignancy (check PTHrP), granulomatous disease (check 1,25-D), meds.

Outpatient #1

Primary hyperparathyroidism (elevated PTH + elevated Ca). Parathyroid adenoma most common. Surgery if symptomatic or meets criteria.

Inpatient #1

Malignancy: humoral (PTHrP -squamous, RCC, breast), osteolytic (myeloma, breast mets), 1,25-D production (lymphoma).

Treatment Order

(1) NS 200-300 mL/hr (most important), (2) calcitonin (fast, bridges to bisphosphonate, tachyphylaxis at 48h), (3) zoledronic acid (most effective, onset 2-4 days). No furosemide unless overloaded.

Severe Ca > 14

Aggressive hydration + calcitonin + zoledronic acid. ICU if cardiac symptoms, AMS, or severe dehydration. ECG: short QT.

Symptoms

Stones (renal), bones (pain, fractures), groans (abdominal pain, constipation, pancreatitis), moans (AMS, depression), overtones (polyuria, dehydration).

📄 One Pager

Endocrine / Oncology · One Pager

Hypercalcemia

PTH is the branch point. Outpatient #1: primary hyperparathyroidism. Inpatient #1: malignancy. NS hydration first → calcitonin → zoledronic acid. No furosemide unless overloaded.

🧪 Etiology -PTH Branch

PTH elevated: primary hyperparathyroidism (parathyroid adenoma). PTH suppressed: malignancy (PTHrP → squamous, RCC, breast), granulomatous disease (sarcoid, TB → 1,25-D), vitamin D toxicity, lytic bone mets.

🚨 Treatment

(1) NS 200-300 mL/hr (most important -rehydrate first). (2) Calcitonin 4 IU/kg IM q12h (fast onset, bridges to bisphosphonate, tachyphylaxis at 48h). (3) Zoledronic acid 4 mg IV over 15 min (most effective, onset 2-4 days).

⚠️ Symptoms -Stones, Bones, Groans, Moans

Stones (renal), Bones (pain, fractures), Groans (constipation, abd pain, pancreatitis), Moans (depression, AMS), Overtones (polyuria, dehydration, short QT).

💊 Key Drugs

NS200-300 mL/hr

Calcitonin4 IU/kg IM q12h

Zoledronic acid4 mg IV over 15 min

Denosumab120 mg SQ (if bisphosphonate fails)

⚠️ Pitfalls

Furosemide for hypercalcemia (only if volume overloaded -most patients are dehydrated)
Not checking PTH first (the diagnostic branch point)
Delayed hydration
Missing malignancy as cause in hospitalized patients