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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Hematology

Anemia Workup

Systematic MCV-based approach: microcytic (iron deficiency #1), normocytic (chronic disease, hemolysis, bleeding), macrocytic (B12/folate, MDS, alcohol). Every anemia deserves a reticulocyte count.

🔍 Overview

Overview

Anemia = Hgb < 13 (men) or < 12 (women). Affects ~25% of hospitalized patients. The approach is MCV-driven: Microcytic (MCV < 80): iron deficiency (#1 worldwide), thalassemia, anemia of chronic disease (can be micro or normo), sideroblastic, lead poisoning. Normocytic (MCV 80-100): anemia of chronic disease/inflammation (#1 inpatient), acute blood loss, hemolysis, CKD (EPO deficiency), mixed deficiency. Macrocytic (MCV > 100): B12/folate deficiency, MDS, alcohol/liver disease, hypothyroidism, medications (methotrexate, hydroxyurea, AZT). The reticulocyte count is the most underordered and most important second test -it tells you whether the marrow is responding appropriately (high retic = destruction/loss) or failing (low retic = production problem).

🧪 Workup

Workup

Step 1 -CBC + reticulocyte count + peripheral smear
- Reticulocyte index > 2%: marrow is responding → blood LOSS or DESTRUCTION (hemolysis)
- Reticulocyte index < 2%: marrow failure → production problem
Step 2 -MCV-based workup:
- Microcytic: Iron studies (ferritin, TIBC, serum iron, transferrin sat). Ferritin < 30 = iron deficiency (in inflammation: ferritin < 100 is likely iron deficient). Thalassemia: Mentzer index (MCV/RBC < 13 = thalassemia trait), Hgb electrophoresis.
- Normocytic: BMP (CKD), CRP/ESR (chronic disease), hemolysis labs (LDH, haptoglobin, indirect bili, DAT), reticulocyte count. If hemolysis: Coombs positive = autoimmune (AIHA). Coombs negative = mechanical (TTP, DIC, valve), PNH, G6PD, sickle cell.
- Macrocytic: B12 + folate (if equivocal: methylmalonic acid for B12, homocysteine for both). TSH. LFTs. Peripheral smear (hypersegmented neutrophils = megaloblastic). Consider bone marrow biopsy if unexplained (MDS).
Iron studies interpretation:
- Iron deficiency: ferritin ↓, TIBC ↑, iron ↓, TfSat < 20%
- Chronic disease: ferritin ↑ (or normal), TIBC ↓, iron ↓, TfSat 15-20%
- Iron deficiency + chronic disease: ferritin 30-100 (unreliably elevated by inflammation), TIBC variable. Check soluble transferrin receptor (sTfR) -elevated = true iron deficiency even with inflammation.

🚨 Management

Management

Iron deficiency anemia:
- Oral: ferrous sulfate 325 mg (65 mg elemental Fe) every other day on empty stomach with vitamin C IRON-MIDE, 2020. Every-other-day dosing is as effective as daily (hepcidin rebound). Avoid with PPIs, calcium, coffee.
- IV iron: if oral intolerant, CKD, inflammatory bowel disease, Hgb < 7, or pre-surgical. Iron sucrose 200 mg × 5 doses or ferric carboxymaltose 750 mg × 2 or low-molecular-weight iron dextran 1000 mg × 1 (single dose, monitor for anaphylaxis × 1h).
- Always find the source: premenopausal women → menstrual loss. Men or postmenopausal → GI source until proven otherwise (EGD + colonoscopy). Celiac screening if no GI source found.
B12 deficiency: IM cyanocobalamin 1000 mcg daily × 7d → weekly × 4wk → monthly lifelong. High-dose oral (1000-2000 mcg/day) is an alternative for compliant patients without malabsorption.
Anemia of chronic disease: Treat underlying condition. EPO-stimulating agents (epoetin alfa, darbepoetin) for CKD (target Hgb 10-11, not higher [TREAT, CREATE]). IV iron if concurrent iron deficiency (TfSat < 20%, ferritin < 100).
Transfusion: Hgb < 7 (restrictive threshold TRICC, 1999). < 8 if ACS or symptomatic. 1 unit at a time → recheck.

💊 Medications

Medications

Drug	Dose	Route	Notes
Ferrous sulfate	325 mg (65 mg elemental) every other day	PO	Empty stomach + vitamin C for absorption. Every-other-day = daily efficacy with fewer GI SEs. Avoid PPIs, Ca, coffee. IRON-MIDE, 2020
Epoetin alfa	50-300 IU/kg TIW	SQ	CKD anemia (target Hgb 10-11). VTE risk if Hgb > 11. Iron replete first (TfSat > 20%, ferritin > 100). TREAT, 2009

Monitoring

🏥 Rounds

Pimp Questions

❓ What is the most important second test after CBC in anemia workup?

Reticulocyte count. It differentiates production problems (low retic: marrow failure, nutrient deficiency) from destruction/loss (high retic: hemolysis, bleeding). Calculate the reticulocyte index (RI) = retic % × (patient Hgb / normal Hgb) ÷ maturation factor. RI > 2 = appropriate marrow response. RI < 2 = inadequate. Most underordered test in anemia workup.

❓ How do you diagnose iron deficiency in a patient with concurrent inflammation?

Ferritin is an acute phase reactant -inflammation falsely elevates it. A "normal" ferritin of 60 in a patient with CRP of 80 may actually represent iron deficiency. Rules: (1) ferritin < 30 = iron deficient regardless of inflammation. (2) Ferritin 30-100 with inflammation = likely iron deficient. (3) Best additional test: soluble transferrin receptor (sTfR) -elevated in true iron deficiency, NOT affected by inflammation. TfSat < 20% also supports iron deficiency.

❓ Why should oral iron be taken every other day rather than daily?

IRON-MIDE, 2020 demonstrated that every-other-day dosing is as effective as daily for iron repletion. The mechanism: an oral iron dose triggers hepcidin release (iron-regulatory hormone) that peaks at 24h and blocks iron absorption for ~48h. A second daily dose is largely not absorbed and only causes GI side effects (nausea, constipation). Every-other-day dosing allows hepcidin to fall between doses → better absorption per dose with fewer side effects.

❓ When must you find the source of iron deficiency anemia?

Always in men and postmenopausal women -GI malignancy (colon cancer) until proven otherwise. Get EGD + colonoscopy. In premenopausal women, menstrual loss is the most common cause, but if heavy menstruation doesn't explain the severity, or if there are GI symptoms → scope. Also consider: celiac disease (anti-TTG), gastric bypass (iron absorption site bypassed), chronic NSAID use (GI erosions).

❓ What peripheral smear findings help differentiate causes of anemia?

Target cells: thalassemia, iron deficiency, liver disease. Schistocytes: TTP, DIC, mechanical valve hemolysis. Spherocytes: autoimmune hemolysis (AIHA), hereditary spherocytosis. Hypersegmented neutrophils: B12/folate deficiency (megaloblastic). Teardrop cells + leukoerythroblastic: myelofibrosis/marrow infiltration. Sickle cells: SCD. Rouleaux: myeloma, inflammation. Bite cells/Heinz bodies: G6PD deficiency.

Clinical Examples

📋 Case 1, Iron Deficiency with Occult GI Malignancy

Patient: 62-year-old postmenopausal woman presents with fatigue and exertional dyspnea over 3 months. No overt bleeding. PMH: GERD on omeprazole.

Key findings: Hgb 7.8, MCV 68, ferritin 6, TIBC 480, TfSat 5%, reticulocyte index 0.4%. Smear: microcytic hypochromic RBCs, pencil cells. FIT positive.

Management:

Transfuse 1 unit pRBC (symptomatic, Hgb < 7 threshold) TRICC, 1999
IV iron (ferric carboxymaltose 750 mg x 2 doses)
EGD + colonoscopy: cecal mass found, biopsy confirmed adenocarcinoma

Teaching point: New iron deficiency anemia in a man or postmenopausal woman = GI malignancy until proven otherwise. Never just replace iron without finding the source.

📋 Case 2, B12 Deficiency Mimicking Leukemia

Patient: 45-year-old woman with history of gastric bypass presents with fatigue, paresthesias in feet, and unsteady gait for 6 months.

Key findings: Hgb 8.0, MCV 118, WBC 3.2, platelets 110 (pancytopenia). Smear: macro-ovalocytes, hypersegmented neutrophils. B12 undetectable, methylmalonic acid markedly elevated.

Management:

IM cyanocobalamin 1000 mcg daily x 7 days, then weekly x 4 weeks, then monthly lifelong
Monitor for reticulocyte crisis at day 5-7
Monitor potassium and phosphate (drop during rapid erythropoiesis)

Teaching point: Severe B12 deficiency causes pancytopenia mimicking leukemia. Always check B12 before bone marrow biopsy. Hypersegmented neutrophils are pathognomonic for megaloblastic anemia. Neurologic damage may be irreversible.

📋 Case 3, Mixed Anemia of Chronic Disease + Iron Deficiency

Patient: 58-year-old man with rheumatoid arthritis on methotrexate admitted for flare. Hgb 9.4, MCV 82.

Key findings: Ferritin 85 (ambiguous in inflammation), TIBC 220 (low), TfSat 15%, CRP 68, soluble transferrin receptor (sTfR) elevated at 4.2. Reticulocyte index 0.8.

Management:

Elevated sTfR confirms concurrent iron deficiency despite "normal" ferritin
IV iron sucrose 200 mg x 5 doses (oral poorly absorbed in active inflammation)
Treat underlying RA flare to reduce hepcidin-mediated iron sequestration

Teaching point: Ferritin is an acute phase reactant. A "normal" ferritin of 85 with CRP of 68 likely represents iron deficiency. In inflammation, ferritin less than 100 is suggestive of concurrent iron deficiency. sTfR is the best differentiating test.

Sample Presentation

Mrs. Martinez is a 52-year-old postmenopausal woman presenting with fatigue × 3 months. No bleeding, no melena. PMH: GERD on omeprazole. Labs: Hgb 8.2, MCV 72, ferritin 8, TIBC 450, TfSat 8%, reticulocyte index 0.5%.

Key Points: Classic iron deficiency anemia -microcytic, low ferritin, high TIBC, low TfSat, low retic (production problem). Postmenopausal woman = GI source until proven otherwise. Needs EGD + colonoscopy. Start oral iron (every other day with vitamin C). Consider IV iron if oral intolerant or Hgb < 7. Celiac screen (anti-TTG) if GI workup negative. PPI may impair iron absorption.

Reticulocyte count at day 5-7 -after starting B12 or iron. Expected "retic crisis" = brisk reticulocytosis confirming marrow response.
CBC + reticulocyte at 2-4 weeks -Hgb should begin rising. If not → reassess diagnosis, compliance, concurrent iron deficiency.
Ferritin at 8-12 weeks -on oral iron. Target ferritin > 100 (or > 200 in CKD). Continue oral iron 3-6 months after Hgb normalizes to replete stores.
K⁺, PO₄ -drop during rapid erythropoiesis (B12 repletion, EPO therapy). Monitor and replace.
Iron studies before EPO -functional iron deficiency is #1 cause of EPO resistance. TfSat < 20% or ferritin < 100 → give IV iron.
Hemolysis markers -if autoimmune: DAT, LDH, haptoglobin, reticulocyte count. Trending LDH is the simplest way to monitor hemolytic activity.

Monitoring

📋 Summary

Summary

Step 1

CBC + reticulocyte count + peripheral smear. Retic high = loss/destruction. Low = production.

Microcytic

Iron studies. Ferritin < 30 = iron deficient. Ferritin 30-100 with inflammation = likely iron deficient. Mentzer < 13 = thalassemia.

Normocytic

CKD (EPO), chronic disease (CRP), hemolysis (LDH, hapto, DAT), bleeding (retic + guaiac).

Macrocytic

B12 + folate + TSH + LFTs. Hypersegmented neutrophils = megaloblastic. MDS if unexplained.

Iron Rx

Oral: every other day + vitamin C. IV if intolerant/CKD/severe. Always find the source.

Pearl

Reticulocyte count is the most underordered test. Ferritin is an acute phase reactant. Smear is free and diagnostic.

📄 One Pager

One-Pager

Anemia Workup

MCV → Retic → Smear

Algorithm

Step 1: CBC + retic + smear. Step 2: MCV-based labs (micro → iron studies; normo → hemolysis labs + CKD; macro → B12/folate). Step 3: Bone marrow if unexplained.

Iron Studies Cheat Sheet

IDA: ferritin ↓, TIBC ↑, TfSat ↓. ACD: ferritin ↑, TIBC ↓, TfSat low-normal. IDA+ACD: ferritin 30-100, check sTfR. Hemolysis: LDH ↑, haptoglobin ↓, retic ↑, DAT±.

Trials

TRICC 1999 (restrictive transfusion) · IRON-MIDE 2020 (every-other-day iron) · TREAT 2009 (EPO in CKD)