Post on 10-Oct-2014
USMLE Step 1 High Yield Summary
USMLE Step 1 High Yield Summary
A Crunch Time Cram The following pages contain high yield information designed for review in the days just
preceding the Step 1 examination.
MOST COMMON
Often on the USMLE exam, the student finds two responses that could potentially answer a
question. The NBME is testing the student to identify the more common of the two responses;
for example, the more common cause, site, or type. Below is a high yield summary of the most
common characteristics of the various disorders listed in this text.
Nervous System
Most Common…
Aneurysm of Circle of
Willis
Anterior communicating artery; bitemporal hemianopsia
Blindness Diabetic retinopathy
Blindness—preventable Chlamydia trachomatis
Bacterial meningitis—
elderly Streptococcus pneumoniae
Bacterial meningitis—
newborns E. coli
Bacterial meningitis—
toddlers
Haemophilus influenza type b
Bacterial meningitis—
young adults Neisseria meningitidis
Cancer of the brain—child Medulloblastoma (cerebellum)
Cancer of the brain—adult Astrocytoma (including glioblastoma multiforme), then
metastasis, meningioma, schwannoma
Dementia 1. Alzheimer's 2. Multi-infarct dementia
Demyelinating disease Multiple sclerosis
Location of adult brain
tumors Above tentorium
Location of childhood
brain tumors
Below tentorium (Mnemonic: Children are short, they cannot reach
above the tentorium)
Mental retardation 1. Down syndrome or Fragile X 2. Fetal alcohol syndrome
Motor neuron disease Amyotrophic lateral sclerosis (ALS)
Viral encephalitis HSV
USMLE Step 1 High Yield Summary
Cardiovascular System
Most Common…
Acute mitral insufficiency—children Kawasaki disease
Aneurysm Abdominal aorta
AV fistula Penetrating knife wound
Cancer of the heart—adults Metastases
Cancer of the heart—primary—adults Myxoma “Ball Valve”
Cancer of the heart—primary—kids Rhabdomyoma
Cardiomyopathy Dilated (congestive) cardiomyopathy
Cause of acute endocarditis Staphylococcus aureus
Cause of subacute endocarditis Streptococcus viridans
Congenital cardiac anomaly Ventricular septal defect (membranous >
muscular)
Congenital early cyanosis Tetralogy of Fallot
Coronary artery thrombosis Left anterior descending
Death in HTN 1. Acute mitral insufficiency 2. Lenticulostriate stroke
3. Renal failure (benign nephrosclerosis)
Death in the United States Ischemic heart disease
Heart murmur Mitral valve prolapsed
Heart valve in bacterial endocarditis Mitral
Heart valve in bacterial endocarditis in IV drug
users
Tricuspid
Heart valve involved in rheumatic fever Mitral > Aortic
Hypertension 1. Essential (95%)
2. Renal disease
Hypertension—children Renal disease; cystic disease, Wilms tumor
Hypertension—young women Oral contraceptives
Myocarditis Coxsackie B virus
Right heart failure Left heart failure
Secondary hypertension Renal disease
Sites of atherosclerosis Abdominal aorta > coronary > popliteal >
carotid
Vasculitis (of medium and small arteries) Temporal arteritis
Respiratory System
Most Common…
Cause of pneumonia in debilitated,
hospitalized patient
Klebsiella
Cause of epiglottitis Haemophilus influenza type b
Cause of IV drug user
bacteremia/pneumonia Staphylococcus aureus
USMLE Step 1 High Yield Summary
Cause of opportunistic infection of
AIDS Pneumocystis carinii is most common overall
Death in Alzheimer patients Pneumonia
Fatal genetic defect in Caucasians Cystic fibrosis
Pneumonia—community—typical 1. Streptococcus pneumoniae
2. H. influenza
3. Klebsiella
Pneumonia—hospital acquired 1. Klebsiella
2. Pseudomonas
3. E. coli
Pneumonia—community—atypical 1. Mycoplasma 2. Legionella
Pulmonary HTN COPD
SIADH Small cell carcinoma of the lung
Tracheoesophageal fistula Lower esophagus communicates with trachea, upper
esophagus ends in blind pouch
Gastrointestinal System
Most Common…
Bug in food poisoning Staphylococcus aureus
Bug in GI tract 1. Bacteroides 2. E. coli
Cancer of the appendix Carcinoid—rarely metastasizes
Cancer of the esophagus Leiomyoma
Cancer of the esophagus—
malignant
Squamous cell carcinoma (60%) > adenocarcinoma (40%)
Cancer of the liver Metastasis; lung > GI
Cancer of the liver—primary,
benign
Cavernous hemangioma
Cancer of the liver—primary Hepatocellular carcinoma
Cancer of the mouth Squamous cell carcinoma or mucoepidermoid
carcinoma
Cancer of the mouth—upper lip Basal cell carcinoma
Cancer of the nasal cavities Squamous cell carcinoma
Cancer of the pancreas Adenocarcinoma (usually in the head of pancreas)
Cancer of the salivary glands Pleomorphic adenoma
Cancer of the small bowel Carcinoid—frequent metastasis from ileum
Cancer of the spleen—benign Cavernous hemangioma
USMLE Step 1 High Yield Summary
Cancer of the stomach Gastric adenocarcinoma (intestinal type or diffuse type)
Cirrhosis Alcohol
Congenital GI anomaly Meckel diverticulum
Diarrhea—children Rotavirus
Dietary deficiency Iron
GI obstruction 1. Adhesions 2. Indirect inguinal hernia
Intussusception Terminal ileum into cecum
Liver disease Alcoholic liver disease
Liver infection Viral hepatitis—HVA
Lysosomal storage disease Gaucher disease
Portal hypertension Cirrhosis
Protozoal diarrhea Giardia
Site of diverticula Sigmoid colon
Surgical emergency Acute appendicitis
Worm infection in the United States 1. Pinworm 2. Ascaris
Renal System
Most Common…
Amyloidosis Immunologic (Bence Jones protein in multiple myeloma is also called
the amyloid light chain)
Death in SLE patients Lupus nephropathy type IV (diffuse proliferative)
End-stage renal disease Diabetes
Glomerulonephritis IgA nephropathy (aka Berger's)
Nephrotic syndrome—
adults
Membranous glomerulonephritis
Nephrotic syndrome—
kids Minimal change disease
Renal failure Acute tubular necrosis
Endocrine System
Most Common…
Addison disease 1. Autoimmune 2. Infection
Cancer of the adrenal medulla—
adults Pheochromocytoma
Cancer of the adrenal medulla—kids Neuroblastoma
Cancer of the pituitary 1. Prolactinoma 2. Somatotropic “acidophilic” adenoma
Cancer of the thyroid Papillary carcinoma
Congenital adrenal hyperplasia 1. 21-Hydroxylase deficiency 2. 11-hydroxylase deficiency
USMLE Step 1 High Yield Summary
Cushing's 1. Exogenous steroid therapy 2. Primary ACTH tumor
3. Adrenal adenoma
4. Ectopic ACTH tumor
Enzyme deficiency 21 hydroxylase—95% of congenital adrenal
hyperplasia
Hypercalcemia Hyperparathyroidism
Hyperparathyroidism—primary 1. Solitary adenomas 2. Parathyroid hyperplasia
3. Parathyroid carcinoma
Hyperparathyroidism—secondary Hypocalcemia due to chronic renal failure
Hyperthyroidism Graves disease
Hypopituitarism—adults Nonfunctioning pituitary adenoma
Hypopituitarism—kids Craniopharyngioma
Hypothyroidism Hashimoto thyroiditis
Peripheral neuropathy Diabetes mellitus
Thyroid disease Goiter
Reproductive System
Most Common…
Breast mass (premenopausal) Fibrocystic change (premenopausal)
Breast mass (postmenopausal) Breast carcinoma
Cancer in gynecologic—malignancy Endometrial carcinoma
Cancer in men Prostate carcinoma
Cancer in women Leiomyoma (fibroids)
Cancer in women—malignant Breast carcinoma
Cancer of the breast Infiltrating ductal adenocarcinoma
Cancer of the ovary—benign Serous cystadenoma
Cancer of the ovary—malignant Serous cystadenocarcinoma
Cancer of the placenta—benign Cavernous hemangioma
Cancer of the testicles Seminoma
Cancer that invades the female GU tract Endometrial adenocarcinoma
Cause of PID Neisseria gonorrhoeae or Chlamydia
Chromosomal disorder Down syndrome
Hernia Indirect
Opportunistic infection in AIDS Pneumocystis carinii
Sexually transmitted disease Chlamydia
Musculoskeletal System
USMLE Step 1 High Yield Summary
Most Common…
Bacterial arthritis in young Adults N. gonorrhea
Cancer of the bone Metastases from breast and prostate
Cancer of the bone—primary—adults Multiple myeloma
Cancer of the connective tissue—benign Lipoma
Cancer of the skin Basal cell carcinoma
Carpal bone dislocation Lunate
Carpal bone fx Scaphoid
Disk herniation L4-L5
The Hematopoietic and Lymphoreticular System
Most Common…
Cancer—leukemia—14 y old ALL
Cancer—leukemia—60 y old CLL
Cancer—leukemia—15-39 y
old AML
Cancer—leukemia—40-60 y
old CML
Cancer in infancy Hemangioma
Cancer in children 1. Leukemia
2. Medulloblastoma of cerebellum
Cancer; malignant lymphoma
in children Burkitt lymphoma
Cancer; site of metastasis Regional Iymph nodes
Cancer; site of metastasis (2nd
most common) Liver
Cancer; genetic alteration p53
Hereditary bleeding disorder von Willebrand Disease
Single gene disorder Thalassemia
Type of hodgkin lymphoma Mixed cellularity versus lymphocytic predominance,
lymphocytic depletion, and nodular sclerosis
Type of nonhodgkin
lymphoma Follicular, small cleaved
USMLE Step 1 High Yield Summary
QUICK LISTS
The following Quick Lists contain high yield information organized by basic science subject.
Physiology
Quick List: Important Formulas
Formula Notes
Cardiac output CO = Rate of O2 Consumption/(Arterial O2
Content - Venous O2 Content)
CO = SV × HR
SV = Stroke volume
HR = Heart rate
Mean arterial
pressure
MAP = CO × TPR
MAP = 1/3 SBP + 2/3 DBP
CO = Cardiac output
TPR = Total peripheral
resistance
SBP = Systolic blood pressure
DBP = Diastolic blood
pressure
Stroke volume EDV - ESV EDV = End diastolic volume
ESV = End systolic volume
Ejection fraction SV/EDV × 100 SV = Stroke volume
EDV = End diastolic volume
Resistance 8ηL/πr4 η= Viscosity
L = length
r = radius
Net filtration
pressure
(PC - PI) - (πC - πI) PC = Hydrostatic capillary
pressure
PI = Hydrostatic interstitial
pressure
πC = Osmotic capillary
pressure
πI = Osmotic interstitial
pressure
USMLE Step 1 High Yield Summary
Glomerular
filtration rate
GFR = Kf (PGC - PBS) - (πGC - πBS)
GFR = Cinulin = Uinulin × V/Pinulin
Kf = filtration constant
PGC = Hydrostatic pressure in
glomerular capillaries
PBS = Hydrostatic pressure in
Bowman's space
πGC = Osmotic pressure in
glomerular capillaries
πBS = Osmotic pressure in
Bowman's space
Cinulin = Clearance of PAH
Uinulin = Urine concentration of
PAH
V = Urine flow rate
Pinulin = Plasma concentration
of PAH
Effective renal
plasma flow
CPAH = UPAH × V/PPAH CPAH = Clearance of PAH
UPAH = Urine concentration of
PAH
V = Urine flow rate
PPAH = Plasma concentration
of PAH
Renal blood flow RPF/(1-Hct) RPF = Renal plasma flow
Hct = Hematocrit
Filtration fraction GFR/RPF GFR = Glomerular filtration
rate
RPF = Renal plasma flow
USMLE Step 1 High Yield Summary
Free water
clearance
CH2O = V - Cosm, where
Cosm = Uosm V/Posm
CH2O = Clearance of water
Uosm = Urine osmolarity
Posm = Plasma osmolarity
V = Urine flow rate
Biostatistics
Quick List: Important Formulas
Formula
Sensitivity TP/(TP + FN)
Specificity TN/(TN + FP)
Positive predictive value TP/(TP + FP)
Negative predictive value TN/(TN + FN)
Prevalence TP + FN/(TP + FP + TN + FN)
Generally calculated by incidence × duration of disease
Incidence Generally calculated by number of new cases/susceptible population
Relative risk RR = [TP/(TP + FP)]/[FN/(FN + TN)]
Attributable risk AR = [TP/(TP + FP)]-[FN/(FN + TN)]
Genetics
Quick List: Inherited diseases
Mode of
inheritance Diseases
Autosomal
dominant
diseases
Adult polycystic kidney disease, familial hypercholesterolemia, Marfan
syndrome, Neurofibromatosis type 1, Neurofibromatosis type 2, Tuberous
sclerosis, von Hippel—Lindau disease, Huntington disease, Familial
adenomatous polyposis, Hereditary spherocytosis, Achondroplasia
Autosomal
recessive
diseases
Cystic fibrosis, albinism, alpha1-antitrypsin deficiency, phenylketonuria,
thalassemias, sickle cell anemia, glycogen storage disease,
mucopolysaccharidoses (except Hunter disease), sphingolipidoses (except
Fabry disease), infant polycystic kidney disease, hemochromatosis
X-linked
dominant
diseases
Hypophosphatemic rickets
X-linked
recessive
diseases
Bruton's agammaglobulinemia, Wiskott-Aldrich syndrome, Fragile X
syndrome, G6PD deficiency, ocular albinism, Lesch-Nyhan syndrome,
Duchenne muscular dystrophy, Hemophilia A and B, Fabry disease, Hunter
USMLE Step 1 High Yield Summary
syndrome
Mitochondrial
disease
Leber hereditary optic neuropathy, mitochondrial myopathies
Trisomies Down syndrome (Chromosome 21), Edward syndrome (Chromosome 18),
Patau syndrome (Chromosome 13)
Trinucleotide
repeat diseases
Huntington diease, myotonic dystrophy, Friedreich ataxia, fragile X syndrome
Pharmacology
Quick List: Important Formulas
Formula Notes
Volume of
distribution
Total drug in body/plasma concentration
Clearance Rate of elimination of drug/plasma
concentration
Half life 0.7 × Volume of distribution/Clearance
Loading dose Target plasma concentration × Volume of
distribution/Bioavailability
Bioavailability = 1, when
medication given IV
Maintenance
dose
Target plasma concentration ×
Clearance/Bioavailability
Bioavailability = 1, when
medication given IV
Quick List: Important Drug Side Effects based on Organ System (Figure 1)
USMLE Step 1 High Yield Summary
FIGURE 1 Important drug side effects based on organ system
USMLE Step 1 High Yield Summary
Quick List: Drugs to Avoid in Pregnancy
Drug Reason
Atorvastatin Congenital defects, termination of pregnancy
ACE inhibitors (captopril, enalapril, fosinopril,
lisinopril, and quinapril)
Fetal renal malformations
Aminoglycosides Ototoxicity
Chloramphenicol Gray baby syndrome
Erythromycin Acute cholestatic hepatitis (mother),
Embyrotoxic (clarithromycin)
Fluroquinolones Cartilage damage
Griseofulvin Teratogenic
Methysergide Oxytocic effects
Metronidazole Mutagenesis
Ribavirin Teratogenic
Sulfonamides Kernicterus
Tetracyclines Discolored teeth, inhibition of bone growth
Warfarin Teratogenic
Quick List: CYP-450 Interactions
Effect Agent Notes
Inhibitors Isoniazid, sulfonamides, cimetidine,
ketoconazole, erythromycin, grapefruit
juice
Inducers Quinidine, barbiturates, phenytoin,
rifampin, griseofulvin, carbamazepine,
St. John's wort
While induction is the more important effect,
quinidine can both induce and inhibit
different isoforms of CYP-450
Quick List: Antidotes
Toxic agent Treatment
Acetaminophen N-acetylcysteine
Amphetamine Ammonium chloride (acidify urine)
Anticholinesterases Atropine, pralidoxime
Anticholinergic Physostigmine salicylate
Antimuscarinic Physostigmine salicylate
Arsenic Dimercaprol (BAL), sucimer, Penicillamine
Benzodiazepines Flumazenil
Beta blockers Glucagon
Carbon monoxide 100% oxygen, hyperbaric oxygen
Copper Penicillamine
Cyanide Nitrite, hydroxocobalamin, thiosulfate
Digitalis Stop digoxin, normal potassium, lidocaine, anti-dig Fab fragments,
Mg2+
USMLE Step 1 High Yield Summary
Ethylene glycol
(antifreeze)
Ethanol, dialysis, fomepizole
Gold Dimercaprol (BAL), sucimer, Penicillamine
Heparin Protamine
Iron Deferoxamine
Lead CaEDTA, dimercaprol, succimer, penicillamine
Mercury Dimercaprol (BAL), sucimer
Methemoglobin Methylene blue
Methanol Ethanol, dialysis, fomepizole
Opioids Naloxone/natrexone
Organophosphates Atropine, pralidoxime
Salicylate Sodium bicarbonate (alkalinize urine)
Streptokinase Aminocaproic acid
Tricyclic antidepressants Sodium bicarbonate (serum alkalinization)
tPA Aminocaptoic acid
Warfarin Vitamin K, fresh frozen plasma
Microbiology
Quick List: Buzzwords for Microbiological Infections
Clinical characteristics Organism
Branching rods in oral infections Actinomyces israeli
Chancroid Haemophilus ducreyi
Clue cells Gardenella vaginitis
Cold agglutinins Mycoplasma pneumoniae
Currant jelly sputum Klebsiella
Dog or cat bite Pasteurella multocida
Erythema chronicum migrans Lyme disease
Ghon focus Primary tuberculosis
Jarisch—Herxheimer reaction Syphillis—treatment of an asymptomatic patient results in
rapid lysis leading to symptoms
Negri bodies Rabies
Owl's eye CMV
Pediatric infection Haemophilus influenzae
Pneumonia in cystic fibrosis or
burn infections
Pseudomonas aeruginosa
Rash on palms or soles Rocky Mountain Spotted fever, Secondary syphillis
Roth spots in retina Endocarditis
Slapped cheeks Erythema infectiosum
Splinter hemorrhages in finger
nails
Endocarditis
Strawberry tongue Scarlet fever
Suboccipital lymphadenopathy Rubella
USMLE Step 1 High Yield Summary
Sulfur granules Actinomyces israeli
Traumatic open wound Clostridium perfringens
Tabes dorsales Tertiary syphillis
Thumb sign on lateral X-ray Epiglottis (usually with Haemophilus influenzae)
Urethritis, conjunctivitis, arthritis Reiter syndrome
Quick List: Gram Stain Characteristics of Various Bacteria
Gram Stain
Characteristics Organisms
Gram positive cocci Staphylococcus (catalase +), Streptococcus (catalase -), Enterococcus
(catalase -)
Gram positive rods Clostridium (anaerobe), Corynebacterium, Listeria, Bacillius
Gram negative cocci Neisseria
Gram negative coccoid
rods
Haemophilus influenzae, Pasteurella, Brucella, Bordetella pertussis
Gram negative rods Lactose fermenters: Klebsiella (fast*), E. coli (fast), Enterobacter (fast),
Citrobacter (slow*), Serratia (slow)
Lactose nonfermenter: Shigella (oxidase -), Salmonella (oxidase -),
Proteus (oxidase -), Pseudomonas (oxidase +) *
Fast fermenter, Slow fermenter.