Updated: 9/25/2018

Cushing Syndrome

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Snapshot
  •  A 42-year-old obese woman who does not smoke presents with diastolic hypertension and menstrual irregularities. Physical exam shows a full, plethoric-appearing face, increased facial hair, truncal obesity, and purple striae around the abdomen. Scattered echymoses are present over the entire body. Labs show a Hgb of 18 g/dL and a WBC of 18,000/mm^3. The leukocyte differential shows an absolute neutrophillic leukocytosis. CXR is normal.
Introduction
  • A condition that refers to the manifestations of hypercortisolism
    • results in hyperplasia of the adrenal cortex
      • specifically the fasiculata
  • There are several types
    • iatrogenic Cushing's
      • patients taking steroids is the most common cause of Cushing's syndrome
    • pituitary adenoma (Cushing's disease)
      • most common pathogenic cause (70%)
      • majority of adenomas are benign
    • adrenal Cushing's 
      • adenoma of the adrenals
    • ectopic Cushing's
      • ectopic ACTH secretion
      • extremely high ACTH
      • most commonly from small cell carcinoma of the lung
        • less commonly thymic cancer
Presentation
  • Symptoms
    • depression and psychological changes
    • oligomenorrhea
    • growth retardation
    • weakness
      • catabolism of muscle for gluconeogenesis
    • symptoms of diabetes (polydipsia, polyuria, and dysuria)
  • Physical exam
    • diastolic hypertension
    • central obesity
    • muscle wasting
    • thin skin that easily bruises/purple abdominal striae
      • due to weakening of collagen
    • hirsutism
    • moon facies
    • buffalo hump
Evaluation
  • Labs
    • hyperglycemia
      • cortisol is gluconeogenic
    • hypokalemia
      • at high concentrations cortisol can have partial activity at the aldosterone receptor
    • screen for 24-hour free urinary cortisol as well as a serum cortisol level
      • high positive and negative predictive value
    • serum ACTH to localize lesion 
      • iatrogenic
        • ↓ ACTH
      • pituitary
        • ↑ ACTH
      • adrenal
        • ↓ ACTH
      • ectopic
        • ↑ ACTH
    • if ACTH is high, then use high dose dexamethasone suppression test 
      • pituitary
        • ↓ cortisol production (i.e. production is suppressible) 
      • ectopic
        • no change in cortisol (i.e. production is NOT suppressible)
 

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Questions (4)
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
Volume  
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
Urine  
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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(M1.EC.74) A 35-year-old Caucasian female presents to the hospital alarmed by her recent truncal weight gain, facial hair growth, and thinning skin. During the physical exam, the physician finds that the patient is hypertensive. Serum analysis reveals hyperglycemia. The physician suspects a pituitary adenoma. Which dexamethasone test result would help confirm the physician's suspicions? Review Topic

QID: 100375
1

Low-dose, increased ACTH; high-dose, increased ACTH

12%

(2/17)

2

Low-dose, increased ACTH; high-dose, decreased ACTH

12%

(2/17)

3

Low-dose, decrease in ACTH; high-dose, no change in ACTH

0%

(0/17)

4

Low-dose, no change in ACTH; high-dose, no change in ACTH

24%

(4/17)

5

Low-dose, no change in ACTH; high-dose, decreased ACTH

53%

(9/17)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 5

(M1.EC.90) A 50-year-old female is evaluated by her physician for recent weight gain. Physical examination is notable for truncal obesity, wasting of her distal musculature and moon facies. In addition she complains of abnormal stretch marks that surround her abdomen. The physician suspects pituitary adenoma. Which of the following high-dose dexamethasone suppression test findings and baseline ACTH findings would support his view? Review Topic

QID: 100391
FIGURES:
1

Cortisol suppression, normal baseline ACTH

13%

(10/75)

2

Cortisol suppression, high baseline ACTH

44%

(33/75)

3

No cortisol suppression, high baseline ACTH

20%

(15/75)

4

No cortisol suppression, low baseline ACTH

11%

(8/75)

5

Elevation of cortisol above pre-test levels, high baseline ACTH

9%

(7/75)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

(M1.EC.96) A 34-year-old Caucasian female presents with truncal obesity, a rounded "moon face", and a "buffalo hump". Serum analysis shows hyperglycemia. It is determined that a pituitary adenoma is the cause of these symptoms. Adrenal examination is expected to show? Review Topic

QID: 100397
1

Atrophy of the adrenal cortex

0%

(0/14)

2

Diffuse hyperplasia of the adrenal cortex

93%

(13/14)

3

Atrophy of the adrenal medulla

0%

(0/14)

4

Adrenal adenoma

7%

(1/14)

5

Atrophy of the adrenal gland

0%

(0/14)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 2
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