11.1 Major Depressive Disorder & Medical Mimics

ABIM Internal Medicine Exam

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1 Chapter 0: The ABIM Exam, Blueprint & Study Strategy

0.1 Exam Format, Question Types & the 2026 Blueprint 0.2 Eligibility, Registration, Fees & Exam-Day Logistics 0.3 Scoring, the Passing Standard & Score Reports 0.4 Building a Blueprint-Weighted Study Plan

2 Chapter 1: Cardiovascular Disease (14% of Exam)

1.1 Ischemic Heart Disease & Acute Coronary Syndromes 1.2 Antithrombotic Therapy, Secondary Prevention & Mechanical Complications of MI 1.3 Atrial Fibrillation, Atrial Flutter & Stroke Prevention 1.4 Supraventricular Tachycardias, Ventricular Arrhythmias & Bradycardias 1.5 Heart Failure: Classification, Staging & Guideline-Directed Medical Therapy 1.6 Device Therapy, HFpEF & the Cardiomyopathies 1.7 Valvular Heart Disease & Endocarditis Prophylaxis 1.8 Pericardial Disease & Acute Aortic Syndromes 1.9 Hypertension: Classification, Diagnosis & Secondary Causes 1.10 Hypertensive Crises & Dyslipidemia 1.11 Adult Congenital Heart Disease & Coarctation of the Aorta 1.12 Syncope: Reflex, Orthostatic & Cardiac Causes 1.13 Cardiac Physical Examination, Murmurs & Antithrombotic Selection

3 Chapter 2: Endocrinology, Diabetes & Metabolism (9% of Exam)

2.1 Diabetes Mellitus: Diagnosis, Glycemic Targets & Pharmacotherapy 2.2 Insulin Therapy, Hyperglycemic Emergencies & Chronic Complications 2.3 Thyroid Function Testing & Hypothyroidism 2.4 Thyrotoxicosis, Thyroid Storm & Thyroid Nodules 2.5 Adrenal & Pituitary Disorders 2.6 Hypercalcemia, Hypocalcemia & Disorders of Mineral Metabolism 2.7 Osteoporosis & Paget Disease of Bone 2.8 Ovarian, Testicular & Reproductive Endocrine Disorders 2.9 Hypoglycemia, Endocrine Tumors, Polyglandular Syndromes & Severe Hypertriglyceridemia

4 Chapter 3: Gastroenterology & Hepatology (9% of Exam)

3.1 Esophageal Disease 3.2 Stomach & Duodenal Disease and Gastrointestinal Hemorrhage 3.3 Inflammatory Bowel Disease 3.4 Celiac Disease & Irritable Bowel Syndrome 3.5 Diverticular Disease & Colorectal Cancer Screening 3.6 Viral Hepatitis, Steatotic & Alcohol-Associated Liver Disease 3.7 Cirrhosis & the Complications of Portal Hypertension 3.8 Acute Pancreatitis 3.9 Chronic Pancreatitis & Biliary Tract Disease 3.10 Inherited, Autoimmune & Drug-Induced Liver Disease 3.11 Small Intestinal Disease, Ischemia & Gastrointestinal Complications of HIV

5 Chapter 4: Infectious Disease (9% of Exam)

4.1 Lower Respiratory Tract Infections & Sepsis Syndromes 4.2 Viral Respiratory Pathogens & Tuberculosis 4.3 Central Nervous System Infections 4.4 Skin, Soft Tissue, Bone & Joint Infections 4.5 Infective Endocarditis & Cardiovascular Infection 4.6 Clostridioides difficile & Catheter-Related Bloodstream Infection 4.7 HIV Diagnosis, Antiretroviral Therapy & Prevention 4.8 Opportunistic Infections & Sexually Transmitted Infections 4.9 Fever of Unknown Origin, Neutropenic Fever & Toxic Shock 4.10 Travel-Related Illness, Vector-Borne Disease & Outbreaks 4.11 Infection Prevention, Nosocomial Infection & Postexposure Prophylaxis 4.12 Rheumatic Fever, Poststreptococcal Disease, Enteric & Hepatic Infections

6 Chapter 5: Pulmonary Disease (9% of Exam)

5.1 COPD: Diagnosis, GOLD Classification & Initial Pharmacotherapy 5.2 Interventions That Reduce COPD Mortality & Exacerbation Management 5.3 Asthma: Diagnosis, Stepwise Therapy & Status Asthmaticus 5.4 Interstitial Lung Disease & Idiopathic Pulmonary Fibrosis 5.5 Sarcoidosis, Hypersensitivity Pneumonitis & Occupational Lung Disease 5.6 Pulmonary Embolism: Diagnosis, Risk Stratification & Anticoagulation 5.7 Pulmonary Hypertension & Sleep-Disordered Breathing 5.8 Acute Respiratory Distress Syndrome & Mechanical Ventilation 5.9 Pleural Disease, Empyema & Pneumothorax 5.10 Bronchiectasis, Cystic Fibrosis & Restrictive Lung Disease 5.11 Evaluation of Cough, Dyspnea, Hemoptysis & the Solitary Pulmonary Nodule

7 Chapter 6: Rheumatology & Orthopedics (9% of Exam)

6.1 Rheumatoid Arthritis: Diagnosis & Systemic Manifestations 6.2 Antirheumatic Pharmacotherapy & the Spondyloarthropathies 6.3 Gout: Pathophysiology & Acute Management 6.4 Urate-Lowering Therapy & Calcium Pyrophosphate Deposition Disease 6.5 Osteoarthritis 6.6 Systemic Lupus Erythematosus 6.7 Systemic Sclerosis, Sjogren Syndrome & Inflammatory Myopathies 6.8 The Vasculitides 6.9 Regional Musculoskeletal Syndromes, Back Pain & Sports Injuries 6.10 Other Primary Rheumatic Disorders & Mixed Connective Tissue Disease 6.11 Osteonecrosis & Metabolic Bone Disease

8 Chapter 7: Hematology (6% of Exam)

7.1 Approach to Anemia & the Microcytic Anemias 7.2 Macrocytic, Normocytic & Hemolytic Anemias 7.3 Hemoglobinopathies, Thalassemias & Paroxysmal Nocturnal Hemoglobinuria 7.4 Platelet Disorders, Thrombocytopenia & the Bleeding Patient 7.5 Coagulation Factor Disorders, Thrombophilia & Anticoagulant Reversal 7.6 Acute Leukemias, Chronic Leukemias & Myeloproliferative Neoplasms 7.7 Lymphomas & Plasma Cell Disorders 7.8 Myelodysplastic Syndrome, Myeloproliferative Neoplasms & Porphyria 7.9 Transfusion Medicine & Late Complications of Transplantation

9 Chapter 8: Medical Oncology (6% of Exam)

8.1 Breast, Lung, Colorectal & Prostate Cancer 8.2 Oncologic Emergencies 8.3 Genitourinary & Gynecologic Malignancies 8.4 Head and Neck, Bone & Soft Tissue Cancer and Cancer of Unknown Primary 8.5 Complications of Cancer & Its Treatment 8.6 Cancer Prevention, Survivorship & Psychosocial Care

10 Chapter 9: Nephrology & Urology (6% of Exam)

9.1 Acute Kidney Injury: Staging, Etiology & Urine Microscopy 9.2 Glomerular Disorders & Nephrotic Syndrome 9.3 Nephritic Syndromes, RPGN & Indications for Renal Replacement Therapy 9.4 Chronic Kidney Disease: Staging & Progression Retardation 9.5 Complications of Chronic Kidney Disease: Anemia, CKD-MBD & Acidosis 9.6 Hyponatremia, Hypernatremia & Water Balance 9.7 Potassium Disorders & Systematic Acid-Base Analysis 9.8 Renal Tubular Acidosis & Nephrolithiasis 9.9 Prostate Disorders, Urinary Incontinence & Other Urologic Conditions 9.10 Cystic Kidney Disease, Obstructive Uropathy, Tubulointerstitial Disease & Hematuria

11 Chapter 10: Neurology (4% of Exam)

10.1 Acute Ischemic Stroke: Syndromes & Reperfusion 10.2 Transient Ischemic Attack, Secondary Prevention & Hemorrhagic Stroke 10.3 Headache & Facial Pain 10.4 Seizures, Epilepsy & Movement Disorders 10.5 Multiple Sclerosis & Neuromuscular Junction Disorders 10.6 Motor Neuron Disease & Acute Peripheral Neuropathy 10.7 Cranial Neuropathies & Neuro-Ophthalmology 10.8 Peripheral Neuropathies, CNS Tumors & Other Neurologic Disorders

12 Chapter 11: Psychiatry & Behavioral Health (4% of Exam)

11.1 Major Depressive Disorder & Medical Mimics 11.2 Antidepressant Pharmacotherapy & Treatment-Resistant Depression 11.3 Bipolar Disorder, Mood Stabilizers & Lithium Toxicity 11.4 Anxiety, Stress-Related & Obsessive-Compulsive Disorders 11.5 Alcohol Use Disorder & Withdrawal 11.6 Pharmacotherapy for Alcohol & Opioid Use Disorder 11.7 Toxidromes, Psychiatric Emergencies & Suicide Risk Assessment 11.8 Psychotic, Somatic Symptom, Factitious & Personality Disorders 11.9 Eating Disorders, Sleep Disorders & Sexual Health

13 Chapter 12: Dermatology (3% of Exam)

12.1 Dermatitis, Papulosquamous & Inflammatory Dermatoses 12.2 Acne, Rosacea & Cutaneous Infections 12.3 Herpes Zoster & Autoimmune Blistering Diseases 12.4 Nodules, Tumors & Cutaneous Oncology 12.5 Dermatologic Emergencies & Severe Cutaneous Adverse Reactions 12.6 Pigment Disorders, Alopecia, Nail Disease & Photosensitivity 12.7 Vascular Dermatoses, Environmental Injury & Cutaneous Signs of Systemic Disease

14 Chapter 13: Obstetrics & Gynecology / Women's Health (3% of Exam)

13.1 Contraception, Preconception Care & Teratogenicity 13.2 Hypertensive Disorders of Pregnancy & Gestational Diabetes 13.3 Thyroid Disease & Venous Thromboembolism in Pregnancy 13.4 Menopause & Menopausal Hormone Therapy 13.5 Abnormal Uterine Bleeding, Endometrial Disease & Gynecologic Cancer Screening 13.6 Breast Disorders & Diseases of the Vulva and Vagina 13.7 Menstrual Disorders, Fibroids, Endometriosis & Early Pregnancy Complications

15 Chapter 14: Geriatric Syndromes (3% of Exam)

14.1 Comprehensive Geriatric Assessment & Frailty 14.2 Falls, Gait Assessment & Polypharmacy 14.3 Urinary Incontinence & Pressure Injuries in Older Adults 14.4 Mild Cognitive Impairment, Dementia & Its Subtypes 14.5 Delirium & the Pharmacotherapy of Cognitive Disorders 14.6 Palliative Care, Hospice & Advance Care Planning 14.7 Chronic Wounds, Nutrition, Swallowing, Constipation & Hip Fracture 14.8 Sensory Impairment, Dizziness, Elder Mistreatment & Care Settings

16 Chapter 15: Allergy & Immunology (2% of Exam)

15.1 Anaphylaxis: Recognition & Emergency Management 15.2 Urticaria & Angioedema 15.3 Drug Allergy, Desensitization & Adult Immunodeficiency 15.4 Food Allergy, Insect Venom Hypersensitivity, Serum Sickness & Contrast Reactions 15.5 Rhinitis, Conjunctivitis, Eosinophilic & Mast Cell Disorders

17 Chapter 16: Preventive Medicine, Immunization & Clinical Epidemiology

16.1 The USPSTF Framework & Evidence-Based Cancer Screening 16.2 Cardiovascular & Metabolic Screening and Primary Prevention 16.3 Adult Immunization & Vaccines in Special Populations 16.4 Clinical Epidemiology, Biostatistics & Study Design

18 Chapter 17: Miscellaneous - Ethics, Patient Safety & Quality Improvement (2% of Exam)

17.1 Principles of Bioethics & Decisional Capacity 17.2 Informed Consent, Treatment Refusal & Special Scenarios 17.3 Surrogate Decision-Making, Advance Directives & Confidentiality 17.4 Patient Safety Science, Medical Error & Diagnostic Reasoning 17.5 Quality Improvement Methods, Health Disparities & Health Equity

19 Chapter 18: Perioperative Medicine & Medical Consultation

18.1 Preoperative Cardiovascular Risk Assessment 18.2 Preoperative Pulmonary Risk & Perioperative Medication Management 18.3 Perioperative Anticoagulation, Bridging & Postoperative Complications

20 Chapter 19: Ophthalmology (1% of Exam)

19.1 The Acute Red Eye & Ophthalmic Emergencies 19.2 Painless Vision Loss & Chronic Ophthalmic Disease 19.3 Uveitis, Scleritis & Orbital Disease

21 Chapter 20: Otolaryngology & Dental Medicine (1% of Exam)

20.1 Dizziness, Vertigo & Epistaxis 20.2 Ear Disorders, Hearing Loss & Upper Respiratory Infections 20.3 Oral Cavity, Salivary Gland, Laryngeal & Taste and Smell Disorders

11.1 Major Depressive Disorder & Medical Mimics

Key Takeaways Explain This Topic AI

Depression and suicide, bipolar disorder and other mood disorders are the enumerated blueprint topics under mood disorders.

Diagnosis requires at least five symptoms over two weeks including depressed mood or anhedonia, with functional impairment.

Hypothyroidism, vitamin B12 deficiency, anemia, obstructive sleep apnea, substance use and medication effects must be excluded before attributing symptoms to primary depression.

Every patient being considered for an antidepressant should be screened for a history of mania or hypomania, because monotherapy can precipitate a manic episode.

Suicide risk assessment is a required element of every depression evaluation, including access to lethal means.

Last updated: August 2026

Psychiatric and behavioral health disorders represent one of the most common reasons for primary care visits and internal medicine hospital consultations. Over 20% of primary care patients meet criteria for a depressive or anxiety disorder. For the ABIM Internal Medicine examination, internists must master the diagnostic criteria, rule out organic medical and pharmacologic mimics, select initial pharmacotherapy based on patient comorbidity profiles, execute structured treatment algorithms for inadequate response, manage mood stabilizers and their toxicities in bipolar disorder, and treat anxiety and trauma-related conditions.

1. Major Depressive Disorder (MDD): Diagnostic Criteria & Medical Mimics
DSM-5 Diagnostic Criteria

Major Depressive Disorder is diagnosed when a patient experiences at least 5 of the 9 diagnostic symptoms during the same 2-week period , representing a clear change from previous functioning. At least one of the symptoms must be either (1) Depressed mood or (2) Loss of interest or pleasure (anhedonia) . DSM-5 Diagnostic Mnemonic: "SIG E. CAPS"

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S — Sleep changes (insomnia [initial, middle, or terminal] or hypersomnia)
I — Interest lost (anhedonia — markedly diminished pleasure in almost all activities)
G — Guilt (excessive, inappropriate feelings of worthlessness or guilt)
E — Energy loss (persistent fatigue or loss of energy nearly every day)
C — Concentration impairment (diminished ability to think, concentrate, or make decisions)
A — Appetite / Weight changes (significant weight loss/gain [>5% in a month] or appetite shifts)
P — Psychomotor agitation or retardation (observable by others, not merely subjective restlessness)
S — Suicidal ideation (recurrent thoughts of death, passive ideation, or specific suicide plan/attempt)
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Requirement: >= 5 symptoms for >= 2 consecutive weeks, including depressed mood or anhedonia.

Exclusions: Not attributable to physiological effects of a substance or another medical condition.

Clinical Screening Tools

PHQ-2 (Patient Health Questionnaire-2): Ultra-brief 2-question initial screening tool assessing depressed mood and anhedonia over the past 2 weeks (scored 0-6). A score of >=3 has a sensitivity of 83% and specificity of 92% for MDD and mandates immediate full evaluation with the PHQ-9.

PHQ-9 (Patient Health Questionnaire-9): Validated 9-item diagnostic and severity tool (scored 0-27):

1 to 4: Minimal depression (no pharmacotherapy required)
5 to 9: Mild depression (supportive counseling, lifestyle modification, watchful waiting)
10 to 14: Moderate depression (psychotherapy and/or first-line antidepressant pharmacotherapy)
15 to 19: Moderately severe depression (pharmacotherapy +/- psychotherapy)

20 to 27: Severe depression (immediate pharmacotherapy + psychotherapy; evaluate for hospitalization / suicide risk)

Organic Medical Mimics & Required Diagnostic Evaluation

Before diagnosing primary MDD, secondary medical and pharmacologic etiologies must be systematically evaluated and excluded:

Medical Condition / Organ System Pathophysiology & Clinical Clues Diagnostic Evaluation Management / Board Distinction

Hypothyroidism Decreased metabolic rate, psychomotor slowing, apathy, cold intolerance, constipation, dry skin, delayed relaxation of deep tendon reflexes (Woltman sign) Serum TSH (elevated), Free T4 (low) Levothyroxine replacement resolves depressive symptoms; do not start antidepressants until thyroid status is normalized

Anemia & Iron Deficiency Profound fatigue, exertional dyspnea, pallor, restless legs, pica, poor concentration CBC (low Hb/Hct, microcytosis/macrocytosis), Serum Ferritin (<30-45 ng/mL indicates iron deficiency) Iron repletion (oral ferrous sulfate or IV iron sucrose/ferric carboxymaltose) restores energy and cognitive stamina

Vitamin B12 Deficiency Macrocytic anemia, symmetric subacute combined degeneration (dorsal column loss: vibration/proprioception loss; lateral corticospinal: spasticity), memory loss, depression Serum Vitamin B12 (<200 pg/mL; check Methylmalonic Acid [MMA] and Homocysteine if borderline 200-400 pg/mL) Parenteral cyanocobalamin / oral high-dose B12; prevents irreversible neuropsychiatric and spinal cord damage

Obstructive Sleep Apnea (OSA) Daytime hypersomnolence, morning headaches, loud snoring, witnessed apneas, hypertension, obesity (BMI >30 kg/m²) STOP-BANG questionnaire , In-lab Polysomnography (PSG) or Home Sleep Apnea Testing (AHI >=5 with symptoms or >=15) CPAP therapy directly improves mood, cognitive function, and daytime alertness; antidepressants alone fail to resolve symptoms

Medication-Induced Depression Temporal onset of depressive symptoms within weeks to months of initiating or escalating a culprit pharmacologic agent Clinical medication reconciliation Key Culprit Drugs: ; - Systemic Corticosteroids (prednisone, dexamethasone); - Beta-Blockers (lipophilic agents: propranolol); - Interferon-alpha (high incidence of severe depression/suicidality; pre-screen); - Varenicline (smoking cessation; monitor neuropsychiatric symptoms); - Isotretinoin (acne vulgaris); - Oral Contraceptives / GnRH agonists (leuprolide)

Loading diagram... Major Depressive Disorder: Primary Care Treatment, Optimization, and Augmentation Algorithm

4. Other Mood Disorders in the Blueprint

The mood disorders subsection explicitly names other mood disorders (psychogenic erectile dysfunction, premenstrual dysphoric disorder) alongside depression and bipolar disorder.

Premenstrual dysphoric disorder

A severe, functionally impairing mood disorder confined to the luteal phase , distinct from ordinary premenstrual syndrome by the severity of the affective symptoms and the degree of impairment.

Diagnostic requirements:

At least five symptoms in the final week before menses , improving within a few days of onset of menses and minimal or absent in the week after menses

At least one core affective symptom: marked affective lability, marked irritability or anger, markedly depressed mood, or marked anxiety or tension

Plus additional symptoms such as anhedonia, difficulty concentrating, lethargy, appetite change, hypersomnia or insomnia, a sense of being overwhelmed, and physical symptoms including breast tenderness and bloating

Confirmation by prospective daily symptom ratings over at least two cycles — this is the requirement most often omitted, and retrospective recall substantially over-diagnoses the condition

Significant interference with work, school or relationships

The essential differential is premenstrual exacerbation of an underlying disorder. In premenstrual dysphoric disorder the symptom-free interval after menses is genuinely symptom-free; in premenstrual exacerbation of major depression, bipolar disorder, an anxiety disorder or a personality disorder, symptoms are present throughout the cycle and merely worsen premenstrually. Prospective charting is what distinguishes them , and treating a premenstrual exacerbation as premenstrual dysphoric disorder leaves the underlying illness untreated.

Treatment:

Selective serotonin reuptake inhibitors are first-line and are unusually effective here: unlike in major depression, the response occurs within a day or two , which permits luteal-phase-only or symptom-onset dosing as an alternative to continuous therapy.

Combined oral contraceptives, particularly continuous or extended-cycle regimens, are an option.

GnRH agonists with add-back therapy are reserved for refractory cases.

Cognitive behavioral therapy, exercise and calcium supplementation have supporting evidence.

Psychogenic erectile dysfunction

Also named in this subsection. It is suggested by preserved nocturnal and early-morning erections and by situational rather than global loss of function, with abrupt onset often tied to a relationship or life event. Organic causes produce gradual, global loss. Because depression, anxiety and antidepressant therapy all contribute, the evaluation should assess mood, medications and relationship factors alongside the vascular, neurologic and endocrine causes covered under male reproductive health.