Updated: 11/30/2019

Selective Serotonin Reuptake Inhibitors (SSRIs)

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  • A 64-year-old female was brought to her primary care physician by her daughter due to poor appetite. When eliciting a history, you learn that the patient no longer finds joy in her hobbies, has feelings of worthlessness, is unable to sleep, and has issues concentrating. In addition to psychotherapy, the patient is prescribed sertraline.
  • SSRIs are commonly considered first-line treatment for depression
    • likely through increasing serotonergic activity
    • usually takes 3-8 weeks for therpeutic effects to occur  
  • Drugs
    • citalopram
    • escitalopram
    • fluoxetine
    • fluvoxamine
    • paroxetine
    • sertraline
  • Mechanism
    • likely through decreasing the serotonin reuptake pump in presynaptic neurons
      • this in turn increases synaptic serotonin availability and serotonin receptor occupancy in postsynaptic neurons
      • serotonin reuptake receptor selectivity → relatively benign side-effects
    • cytochrome P450 inhibitor
      • citalopram and escitalopram are the SSRI of choice if you're concerned about drug-to-drug interactions
  • Clinical use
    • major depressive disorder (MDD, first-line treatment)
    • obsessive-compulsive disorder
    • post traumatic stress disorder
    • panic disorder
    • generalized anxiety disorder
    • bulimia nervosa
    • binge eating disorder
    • social phobias
    • hoarding disorder 
  • Toxicity
    • much milder than other depression therapies
    • weight gain
      • fluoxetine has lowest risk
    • can cause QTc prolongation
    • anxiety, agitation, and insomnia
    • GI distress
    • sexual dysfunction (anorgasmia)
      • can use alternative antidepressants such as bupropion and mirtazapine
    • serotonin syndrome
      • anxiety, restlessness, disorientation, autonomic manifestations (i.e., diaphoresis, hyperthermia, hypertension), and neuromuscular hyperactivity (i.e., myoclonus, hyperreflexia, muscle rigidity, tremor)
    • SSRI discontinuation syndrome
      • with abrupt discontinuation of the medication
      • fluoxetine is less likely to cause symptoms post abrupt discontinuation

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Questions (2)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2

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(M2.PY.17.4867) A 25-year-old female is brought to the physician by her mother who is concerned about her recent behaviors. The mother states that her daughter has been collecting “useless items” in her apartment over the last year. When she tried to persuade her daughter to throw away several years’ worth of old newspapers, her daughter had an angry outburst and refused to speak to her for two weeks. The patient reluctantly admits that she keeps “most things just in case they become useful later on.” She also states that she has felt less interested in seeing friends because she does not want them to come over to her apartment. She has also not been sleeping well, as her bed has become an additional storage space and she must sleep on her futon instead. The patient states that she is sometimes bothered by the messiness of her apartment, but otherwise doesn't think anything is wrong with her behavior. Physical exam is unremarkable. Which of the following is the best next step in management? Review Topic | Tested Concept

QID: 109614

Cognitive behavioral therapy for obsessive-compulsive disorder




Admission to psychiatric facility




High dose SSRI for hoarding disorder




Tricyclic antidepressant for hoarding disorder




Intervention by patient’s mother to declutter the home



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