Step 1 Basics (USMLE)

4.11 Antibody Review

Rheumatology review for the USMLE Step 1 Exam.

ANA Principles

• ANA (Anti-Nuclear Antibody):
  • Non-specific antibody.
  • Reacts against nuclear antigens, including proteins, DNA, RNA, and nucleic acid-protein complexes.
  • Includes a group of antibodies such as anti-dsDNA, anti-histone, SSA/Ro, SSB/La, Scl-70, anti-aminoacyl-tRNA synthetase (Jo-1).
  • Found in 20-30% of the general public without connective tissue disorder symptoms.
• ANA+ individuals may or may not have a rheumatologic disorder.
• Further workup is needed in ANA+ cases to determine the specific disorder.

Antibodies by Disease Process

• Systemic Lupus Erythematosus (SLE)

  • Anti-dsDNA antibody.
  • Anti-Smith antibody.

• Drug-Induced Lupus

  • Anti-histone antibody.

• Diffuse vs. Limited Scleroderma

  • Diffuse: Anti-Scl-70 (anti-topoisomerase I).
  • Limited: Anti-centromere (often called CREST syndrome, with CREST standing for centromere).

• Sjogren's Syndrome

  • Anti-SSA (Ro).
  • Anti-SSB (La), which usually occurs in the presence of SSA.
  • SSA is considered the Sjogren-specific antibody, leading to the presence of SSB.

• Rheumatoid Arthritis (RA)

  • Anti-CCP (Cyclic Citrullinated Peptide).
  • RF (Rheumatoid Factor) is non-specific.

Thanks for listening!

4.10 Gout and Pseudogout

Rheumotology review for the USMLE Step 1 Exam.

Gout

• Caused by uric acid crystal deposition due to purine metabolism.
• Triggers inflammation when crystals precipitate in cooler joint fluid.
• Presents with severe, red, and swollen monoarticular joints, often in the big toe.
• Diagnosis through synovial fluid analysis.
• Acute treatment: colchicine, NSAIDs, and glucocorticoids.
• Preventive treatment: allopurinol, febuxostat, probenecid, and lifestyle changes.

Pseudogout

• Resulting from calcium pyrophosphate crystal deposition, often due to ATP breakdown.
• Manifests with painful, swollen joints, typically affecting multiple upper extremity joints, especially the knee.
• Diagnosis through synovial fluid analysis.
• Acute treatment resembles gout management.
• No direct preventive treatment to lower calcium pyrophosphate levels.

Thanks for listening!

4.09 Rheumatologic Emergencies

Rheumatology review for USMLE Step 1 Exam

Giant Cell Arteritis (GCA)

• A large vessel vasculitis, mainly in older individuals.
• Symptoms: headache, jaw claudication, vision loss.
• Ischemia from granulomas in large vessels causes vision loss.
• Immediate high-dose corticosteroids are crucial.

Scleroderma Renal Crisis

• A complication of scleroderma.
• Symptoms: finger edema, skin tightening, sudden hypertension, rising creatinine.
• Renal artery fibrosis leads to high blood pressure.
• Treat with IV ACE inhibitor, not steroids.

Acute Transverse Myelitis in SLE

• Inflammation of the spinal cord in lupus.
• Symptoms: bilateral numbness, tingling, weakness.
• Treat with corticosteroids.

Catastrophic Antiphospholipid Syndrome (CAPS)

• A rare, life-threatening form of APS.
• Symptoms: unexplained miscarriages, unexplained clots, multiorgan failure.
• Treat with anticoagulation followed by immune suppression

1.06 Systolic Heart Murmurs

Cardiovascular system review for the USMLE STEP 1 Exam

• Heart murmurs are caused by turbulent blood flow in the heart

• There are 4 different types of systolic murmurs: ventricular septal defect (VSD), patent ductus arteriosus (PDA), aortic stenosis, and mitral or tricuspid regurgitation

• PDA produces a constant, machine-like murmur

• VSD produces a harsh holosystolic murmur

• Aortic stenosis produces a crescendo-decrescendo systolic ejection murmur

• Mitral and tricuspid regurgitation produce a holosystolic high pitched "blowing" murmur

• Mitral valve prolapse produces a mid-systolic click followed by a late systolic murmur

• Aortic regurgitation produces a decrescendo diastolic murmur

• Mitral stenosis produces a rumbling diastolic murmur

5.13 OCD and Related Disorders

Psych review for the USMLE Step 1 Exam

• Obsessive Compulsive Disorder (OCD): Unwanted thoughts (obsessions) and repetitive behaviors (compulsions). Treat with CBT + SSRIs/SNRIs.
• Tic Disorders: Tourette Syndrome involves multiple motor and at least one vocal tic. Treat with Habit Reversal Therapy.
• Body Dysmorphic Disorder: Preoccupation with minor flaws, treat with SSRIs and CBT.
• Trichotillomania: Hair pulling disorder, treat with Habit Reversal Training and sometimes SSRIs.
• PANDAS: Pediatric disorder after strep infection, sudden OCD-like symptoms. Treat with antibiotics, CBT, and SSRIs.

5.12 Anxiety Related Disorders

Psychiatry review for the USMLE Step 1 Exam

• Anxiety is a normal response to threats or stressors in the environment
• Anxiety disorders occur when anxiety causes significant distress or impairment in functioning
• Generalized Anxiety Disorder (GAD) involves persistent and excessive worry about various aspects of daily life for at least 6 months, accompanied by physical symptoms
• Treatment for GAD typically involves a combination of cognitive-behavioral therapy (CBT) and selective serotonin reuptake inhibitors (SSRIs)
• Panic Disorder is diagnosed in individuals who experience spontaneous panic attacks and fear future attacks
• Panic attacks are acute episodes of intense anxiety and physical symptoms
• Treatment for Panic Disorder involves CBT and SSRIs, with SSRIs being the first-line medication
• Agoraphobia is the fear of being in public places where escape may be difficult and often follows a traumatic event
• CBT and SSRIs are the recommended treatment for Agoraphobia
• Social Anxiety Disorder (Social Phobia) involves fear of scrutiny or embarrassment in social situations
• Public speaking can be a significant trigger for individuals with social anxiety disorder
• Beta blockers can be used to treat social anxiety disorder by reducing physical symptoms
• Treatment for social anxiety disorder usually involves CBT, SSRIs, or beta blockers.

5.11 Eating and Feeding Disorders

Psychiatry Review for the USMLE Step 1 Exam

• Eating Disorders:

  • Main disorders: bulimia nervosa, anorexia nervosa, and binge eating disorder.
  • Bulimia and anorexia share anxiety and compensatory behaviors.
  • Anorexia: low body weight, fear of gaining weight, treatment involves slow refeeding.
  • Bulimia: normal weight, signs of forced vomiting, treated with CBT and SSRIs.
  • Binge Eating Disorder: uncontrollable eating, negative emotions, SSRIs and CBT for treatment.

• Feeding Disorders:

  • Occur in children, not related to body image.
  • Common disorders: avoidant/restrictive food intake disorder, rumination disorder, and pica.
  • Avoidant/Restrictive Food Intake Disorder: avoidance or restriction of food intake.
  • Pica: eating non-nutritious substances, common in young children.
  • Rumination Disorder: regurgitation without associated symptoms.

5.10 Mood Disorders (Depression and Bipolar)

Psychiatry Review for the USMLE Step 1 exam

• Mood disorders are persistent disruptions in emotion, categorized into bipolar disorders and depressive disorders.
• Bipolar disorders are characterized by manic or hypomanic episodes, while depressive disorders feature periods of depression.
• Major Depressive Disorder (MDD) is characterized by feelings of sadness, guilt, worthlessness, and anhedonia lasting for at least two weeks.
• SIG E CAPS is an acronym used to remember the symptoms of depression: Sleep changes, Interest loss, Guilt, Energy loss, Concentration difficulties, Appetite changes, Psychomotor retardation, and Suicidal ideation.
• In MDD, at least 5 of the SIG E CAPS symptoms must persist for more than 2 weeks.
• Persistent Depressive Disorder (dysthymia) is a chronic, low-grade form of MDD that lasts for at least two years.
• Mania is a symptom common to all bipolar disorders, characterized by elevated or irritable mood and increased activity or energy.
• Mania lasting for at least 1 week is called a manic episode, while hypomania is a less severe form lasting longer than 4 days.
• The symptoms of mania can be remembered using the mnemonic DIG FAST: Distractibility, Irritable mood/insomnia, Grandiosity, Flight of ideas, Agitation/increased activity, Speedy thoughts/speech, and Thoughtlessness.
• Bipolar I involves manic episodes, and bipolar II involves hypomanic episodes and major depressive episodes.
• Bipolar I requires at least one manic episode, while bipolar II requires depressive episodes.
• Mood stabilizers such as lithium, valproate, carbamazepine, and lamotrigine are used to treat bipolar disorders. Litium is the best (notable exeptions however).
• Antidepressants are contraindicated for bipolar patients due to the risk of flipping into mania.
• The risk of suicide is high in bipolar patients, with 25-50% attempting suicide and 10-15% dying by suicide.
• Cyclothymia is a less common form of bipolar disorder characterized by cycling between hypomania and mild depression over many years.

5.09 Schizophrenia

Psychiatry review for the USMLE Step 1 Exam

• Epidemiology:
  • Slight male predilection (1.4:1 male to female ratio).
  • Men present between 18-25, women between 28-35.
  • Affects about 0.5% of the population.
• Symptoms:
  • Positive symptoms: hallucinations, delusions, disorganized behavior and speech.
  • Negative symptoms: flat affect, anhedonia, apathy, alogia, lack of interest in socialization.
  • Cognitive symptoms: impairments in attention, executive function, working memory.
• Diagnosis:
  • Criteria: two or more symptoms lasting over a month.
  • Schizophreniform disorder if symptoms last less than 1 month.
• Pathophysiology:
  • Excess dopamine in prefrontal cortical pathway (negative symptoms).
  • Excess dopamine in mesolimbic pathway (positive symptoms).
  • Other neurotransmitters may also play a role (especially serotonin excess).
• Treatments:
  • Antipsychotics (D2 receptor antagonists).
  • First-generation antipsychotics: haloperidol, chlorpromazine (more side effects).
  • Second-generation antipsychotics (atypical antipsychotics): aripiprazole, olanzapine, quetiapine, risperidone (lower extrapyramidal side effects, higher metabolic side effects).
• Outcomes:
  • Rule of thirds: one-third full recovery, one-third improved with mild symptoms, one-third require high-level care.

5.08 Cluster C Personality Disorders

Psychiatry review for the USMLE Step 1 Exam

• Introduction:

  • Cluster C personality disorders = anxious/worried.
  • Disorders: avoidant, obsessive-compulsive, dependent.
  • Distinguish from normal traits.

• Avoidant Personality Disorder:

  • Inhibited, introverted, anxious.
  • Fear of rejection, low self-esteem.
  • Characteristics: avoidance, preoccupation with criticism/rejection, social ineptness.
  • Treatment: Anti-anxiety drugs may help temporarily.

• Obsessive-Compulsive Personality Disorder:

  • Perfectionism, inflexibility, diligence.
  • Not OCD; need for control, not obsessions/compulsions.
  • Characteristics: details, work focus, rigidity.
  • Example: Mark, unemployed with attention to detail.

• Dependent Personality Disorder:

  • Excessive reliance on others for support/decisions.
  • Linked to early medical/psychiatric conditions.
  • Characteristics: decision-making, fear of disapproval, reliance.
  • Example: Bob, farm laborer dependent on mother.

• Conclusion:

  • Cluster C = anxiety-driven.
  • Understand characteristics, not specific diagnoses.
  • Examples show impact on lives.