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COMLEX-USA Level 1 (Comprehensive Osteopathic
Medical Licensing Examination of the United
States – Level 1) QUESTIONS AND VERIFIED
ANSWERS LATEST UPDATE
COMLEX-USA Level 1 (Comprehensive Osteopathic Medical Licensing Examination of the United States –
Level 1) coverage in summarized point form, followed by 250 MCQs with rationales in random order,
based on the NBOME examination blueprint (updated 2024), and standard osteopathic and biomedical
science principles.
EXAM COVERAGE (SUMMARIZED POINTS)
• Domain 1 – Osteopathic Principles & Practices (OPP) – 16%: OMM techniques (HVLA, muscle
energy, counterstrain, Chapman‘s reflexes, facilitated positional release, myofascial release, BLT,
Still technique), somatic dysfunction (TART), structural examination, cranial osteopathy,
osteopathic manipulative treatment indications/contraindications, lymphatic techniques,
viscerosomatic and somatovisceral reflexes, postural assessment, gait analysis, palpatory
diagnosis, Fryette‘s principles (type I/II mechanics), inherent motility, patient history for somatic
dysfunction.
• Domain 2 – Human Development / Behavior / Psychiatry – 12%: Erikson‘s psychosocial stages,
Piaget‘s cognitive development, defense mechanisms, major depressive disorder, bipolar,
anxiety disorders (GAD, panic, phobias), PTSD, obsessive-compulsive disorder, somatic symptom
disorders, eating disorders, child and adolescent psychiatry, substance use disorders,
schizophrenia spectrum, organic brain syndromes, doctor-patient relationship, ethical principles,
death and dying (Kübler-Ross).
• Domain 3 – Gross Anatomy & Embryology – 9%: Brachial plexus (roots/trunks/cords/branches),
lumbosacral plexus, cranial nerves (CN I-XII) including nuclei and functions, autonomic nervous
system, blood supply of brain (Circle of Willis), muscular compartments of extremities,
mediastinum, retroperitoneum, inguinal canal (Hesselbach‘s triangle), peritoneal folds, heart
anatomy, lung anatomy, embryology of heart, neural tube defects, branchial arches,
diaphragmatic hernia, GI tract development, renal development, congenital anomalies,
lymphatic drainage of breast (axillary/supraclavicular), portal system, hepatic lobule
microanatomy.
• Domain 4 – Pathology & Pathophysiology – 25%: Cell injury (necrosis, apoptosis), inflammation
(acute/chronic/granulomatous), hemodynamic disorders (edema, hyperemia, congestion,
hemorrhage, thrombosis, embolism, infarction), shock (cardiogenic, hypovolemic, septic,
neurogenic), neoplasia (benign vs. malignant, dysplasia, anaplasia, metastasis, tumor suppressor
genes (p53, Rb), oncogenes), immunopathology (Type I-IV hypersensitivity, autoimmunity,
immunodeficiency), infectious disease pathology (bacterial, viral, fungal, parasitic), specific
organ pathology (CVD, pulmonary, renal, GI, hepatobiliary, endocrine, reproductive,
musculoskeletal, skin, CNS), environmental pathology, nutritional disorders, genetic disorders.
• Domain 5 – Pharmacology – 13%: Autonomic drugs (cholinergic, adrenergic), cardiovascular
drugs (antiarrhythmics, antihypertensives, diuretics, anticoagulants, antiplatelets, statins), CNS
drugs (antidepressants, antipsychotics, anxiolytics, anticonvulsants, anesthetics, opioids,
stimulants), antimicrobials (antibiotics by mechanism, antivirals, antifungals, antiparasitics),
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chemotherapy agents (antineoplastics, mechanisms, side effects), endocrine drugs (insulin, oral
hypoglycemics, thyroid drugs, corticosteroids), GI drugs, respiratory drugs, toxicology
(acetaminophen, salicylates, opioid overdose, alcohol withdrawal, anticholinergic toxidrome).
• Domain 6 – Microbiology & Immunology – 10%: Bacterial classification (Gram+ cocci/rods,
Gram- cocci/rods, anaerobes, spirochetes, atypical), medically important bacteria (Staph, Strep,
Neisseria, Enterobacteriaceae, Pseudomonas, Clostridium, Borrelia, Treponema, Rickettsia,
Mycobacteria), viral classification (DNA/RNA, enveloped/non-enveloped), important viruses
(Herpes, HIV, Hepatitis, Influenza, Respiratory viruses, Arboviruses, Rabies, Papillomavirus),
fungal pathogens (Candida, Aspergillus, Cryptococcus, Histoplasma, Coccidioides, Blastomyces),
parasitic pathogens (malaria, toxoplasma, giardia, entamoeba, helminths), immune system
components (innate and adaptive, B cells, T cells, antibodies, MHC, complement, cytokines),
vaccination schedules, sterilization/disinfection, laboratory diagnosis.
• Domain 7 – Physiology & Biochemistry – 13%: Cellular physiology (transport, signaling, action
potential), autonomic physiology, cardiovascular physiology (cardiac cycle, EKG, baroreceptors,
Starling curve, blood pressure regulation), respiratory physiology (ventilation/perfusion
matching, O2/CO2 transport, acid-base), renal physiology (GFR, reabsorption, secretion, RAAS,
acid-base regulation), GI physiology (motility, secretion, digestion, absorption), endocrine
physiology (hypothalamic-pituitary axis, thyroid, adrenal, pancreas, calcium homeostasis),
neurophysiology (synaptic transmission, sensory/motor pathways, reflexes, sleep, EEG), muscle
physiology (smooth, skeletal, cardiac), biochemical pathways (glycolysis, TCA, oxidative
phosphorylation, gluconeogenesis, glycogen metabolism, fatty acid oxidation, cholesterol
synthesis, amino acid metabolism), vitamins and coenzymes, molecular biology (DNA
replication, transcription, translation, repair mechanisms, gene regulation), enzyme kinetics.
QUESTIONS 1–250
1. A 55-year-old male with a history of hypertension presents with acute-onset tearing chest pain
radiating to the back. Blood pressure is 160/90 in the right arm and 100/60 in the left arm. Which of the
following is the most likely diagnosis?
A) Acute myocardial infarction
B) Pulmonary embolism
C) Aortic dissection
D) Pericarditis
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Rationale: Pulse differential (blood pressure difference between arms) with tearing chest pain radiating
to the back is classic for aortic dissection, often type A involving the ascending aorta.
2. Which of the following Fryette‘s principles describes Type I mechanics of the vertebral column?
A) Neutral mechanics: side-bending and rotation occur in opposite directions
B) Neutral mechanics: side-bending and rotation occur in the same direction
C) Non-neutral mechanics: side-bending and rotation occur in the same direction
D) All motions are coupled in the same direction regardless of neutral
Rationale: Fryette‘s Principle I: When the spine is in a neutral position (not flexed or extended), side-
bending and rotation occur in opposite directions (e.g., side-bend left, rotate right).
3. A patient presents with fever, pharyngitis, and cervical lymphadenopathy. A rapid strep test is
positive. Which antibiotic is the first-line treatment?
A) Amoxicillin
B) Azithromycin
C) Ciprofloxacin
D) Doxycycline
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Rationale: Amoxicillin or penicillin V are first-line for Group A Strep pharyngitis. Azithromycin is used
for penicillin-allergic patients.
4. A 25-year-old woman has multiple episodes of palpitations, sweating, and a sense of impending
doom. These episodes occur suddenly and last 10-15 minutes. Between episodes, she is completely
asymptomatic. What is the most likely diagnosis?
A) Generalized anxiety disorder
B) Panic disorder
C) Social anxiety disorder
D) Specific phobia
Rationale: Panic disorder is characterized by recurrent, unexpected panic attacks (sudden episodes of
intense fear with somatic symptoms) with concern about future attacks.
5. A patient with chronic alcohol use presents with nystagmus, ataxia, and confusion. Which vitamin
deficiency is most likely?
A) Vitamin B12 (cobalamin)
B) Vitamin B1 (thiamine)
COMLEX-USA Level 1 (Comprehensive Osteopathic
Medical Licensing Examination of the United
States – Level 1) QUESTIONS AND VERIFIED
ANSWERS LATEST UPDATE
COMLEX-USA Level 1 (Comprehensive Osteopathic Medical Licensing Examination of the United States –
Level 1) coverage in summarized point form, followed by 250 MCQs with rationales in random order,
based on the NBOME examination blueprint (updated 2024), and standard osteopathic and biomedical
science principles.
EXAM COVERAGE (SUMMARIZED POINTS)
• Domain 1 – Osteopathic Principles & Practices (OPP) – 16%: OMM techniques (HVLA, muscle
energy, counterstrain, Chapman‘s reflexes, facilitated positional release, myofascial release, BLT,
Still technique), somatic dysfunction (TART), structural examination, cranial osteopathy,
osteopathic manipulative treatment indications/contraindications, lymphatic techniques,
viscerosomatic and somatovisceral reflexes, postural assessment, gait analysis, palpatory
diagnosis, Fryette‘s principles (type I/II mechanics), inherent motility, patient history for somatic
dysfunction.
• Domain 2 – Human Development / Behavior / Psychiatry – 12%: Erikson‘s psychosocial stages,
Piaget‘s cognitive development, defense mechanisms, major depressive disorder, bipolar,
anxiety disorders (GAD, panic, phobias), PTSD, obsessive-compulsive disorder, somatic symptom
disorders, eating disorders, child and adolescent psychiatry, substance use disorders,
schizophrenia spectrum, organic brain syndromes, doctor-patient relationship, ethical principles,
death and dying (Kübler-Ross).
• Domain 3 – Gross Anatomy & Embryology – 9%: Brachial plexus (roots/trunks/cords/branches),
lumbosacral plexus, cranial nerves (CN I-XII) including nuclei and functions, autonomic nervous
system, blood supply of brain (Circle of Willis), muscular compartments of extremities,
mediastinum, retroperitoneum, inguinal canal (Hesselbach‘s triangle), peritoneal folds, heart
anatomy, lung anatomy, embryology of heart, neural tube defects, branchial arches,
diaphragmatic hernia, GI tract development, renal development, congenital anomalies,
lymphatic drainage of breast (axillary/supraclavicular), portal system, hepatic lobule
microanatomy.
• Domain 4 – Pathology & Pathophysiology – 25%: Cell injury (necrosis, apoptosis), inflammation
(acute/chronic/granulomatous), hemodynamic disorders (edema, hyperemia, congestion,
hemorrhage, thrombosis, embolism, infarction), shock (cardiogenic, hypovolemic, septic,
neurogenic), neoplasia (benign vs. malignant, dysplasia, anaplasia, metastasis, tumor suppressor
genes (p53, Rb), oncogenes), immunopathology (Type I-IV hypersensitivity, autoimmunity,
immunodeficiency), infectious disease pathology (bacterial, viral, fungal, parasitic), specific
organ pathology (CVD, pulmonary, renal, GI, hepatobiliary, endocrine, reproductive,
musculoskeletal, skin, CNS), environmental pathology, nutritional disorders, genetic disorders.
• Domain 5 – Pharmacology – 13%: Autonomic drugs (cholinergic, adrenergic), cardiovascular
drugs (antiarrhythmics, antihypertensives, diuretics, anticoagulants, antiplatelets, statins), CNS
drugs (antidepressants, antipsychotics, anxiolytics, anticonvulsants, anesthetics, opioids,
stimulants), antimicrobials (antibiotics by mechanism, antivirals, antifungals, antiparasitics),
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chemotherapy agents (antineoplastics, mechanisms, side effects), endocrine drugs (insulin, oral
hypoglycemics, thyroid drugs, corticosteroids), GI drugs, respiratory drugs, toxicology
(acetaminophen, salicylates, opioid overdose, alcohol withdrawal, anticholinergic toxidrome).
• Domain 6 – Microbiology & Immunology – 10%: Bacterial classification (Gram+ cocci/rods,
Gram- cocci/rods, anaerobes, spirochetes, atypical), medically important bacteria (Staph, Strep,
Neisseria, Enterobacteriaceae, Pseudomonas, Clostridium, Borrelia, Treponema, Rickettsia,
Mycobacteria), viral classification (DNA/RNA, enveloped/non-enveloped), important viruses
(Herpes, HIV, Hepatitis, Influenza, Respiratory viruses, Arboviruses, Rabies, Papillomavirus),
fungal pathogens (Candida, Aspergillus, Cryptococcus, Histoplasma, Coccidioides, Blastomyces),
parasitic pathogens (malaria, toxoplasma, giardia, entamoeba, helminths), immune system
components (innate and adaptive, B cells, T cells, antibodies, MHC, complement, cytokines),
vaccination schedules, sterilization/disinfection, laboratory diagnosis.
• Domain 7 – Physiology & Biochemistry – 13%: Cellular physiology (transport, signaling, action
potential), autonomic physiology, cardiovascular physiology (cardiac cycle, EKG, baroreceptors,
Starling curve, blood pressure regulation), respiratory physiology (ventilation/perfusion
matching, O2/CO2 transport, acid-base), renal physiology (GFR, reabsorption, secretion, RAAS,
acid-base regulation), GI physiology (motility, secretion, digestion, absorption), endocrine
physiology (hypothalamic-pituitary axis, thyroid, adrenal, pancreas, calcium homeostasis),
neurophysiology (synaptic transmission, sensory/motor pathways, reflexes, sleep, EEG), muscle
physiology (smooth, skeletal, cardiac), biochemical pathways (glycolysis, TCA, oxidative
phosphorylation, gluconeogenesis, glycogen metabolism, fatty acid oxidation, cholesterol
synthesis, amino acid metabolism), vitamins and coenzymes, molecular biology (DNA
replication, transcription, translation, repair mechanisms, gene regulation), enzyme kinetics.
QUESTIONS 1–250
1. A 55-year-old male with a history of hypertension presents with acute-onset tearing chest pain
radiating to the back. Blood pressure is 160/90 in the right arm and 100/60 in the left arm. Which of the
following is the most likely diagnosis?
A) Acute myocardial infarction
B) Pulmonary embolism
C) Aortic dissection
D) Pericarditis
, Page 3 of 134
Rationale: Pulse differential (blood pressure difference between arms) with tearing chest pain radiating
to the back is classic for aortic dissection, often type A involving the ascending aorta.
2. Which of the following Fryette‘s principles describes Type I mechanics of the vertebral column?
A) Neutral mechanics: side-bending and rotation occur in opposite directions
B) Neutral mechanics: side-bending and rotation occur in the same direction
C) Non-neutral mechanics: side-bending and rotation occur in the same direction
D) All motions are coupled in the same direction regardless of neutral
Rationale: Fryette‘s Principle I: When the spine is in a neutral position (not flexed or extended), side-
bending and rotation occur in opposite directions (e.g., side-bend left, rotate right).
3. A patient presents with fever, pharyngitis, and cervical lymphadenopathy. A rapid strep test is
positive. Which antibiotic is the first-line treatment?
A) Amoxicillin
B) Azithromycin
C) Ciprofloxacin
D) Doxycycline
, Page 4 of 134
Rationale: Amoxicillin or penicillin V are first-line for Group A Strep pharyngitis. Azithromycin is used
for penicillin-allergic patients.
4. A 25-year-old woman has multiple episodes of palpitations, sweating, and a sense of impending
doom. These episodes occur suddenly and last 10-15 minutes. Between episodes, she is completely
asymptomatic. What is the most likely diagnosis?
A) Generalized anxiety disorder
B) Panic disorder
C) Social anxiety disorder
D) Specific phobia
Rationale: Panic disorder is characterized by recurrent, unexpected panic attacks (sudden episodes of
intense fear with somatic symptoms) with concern about future attacks.
5. A patient with chronic alcohol use presents with nystagmus, ataxia, and confusion. Which vitamin
deficiency is most likely?
A) Vitamin B12 (cobalamin)
B) Vitamin B1 (thiamine)
