Endocrinology Book

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HyperthyroidismAka: Thyrotoxicosis

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  1. See Also
    1. Subclinical Hyperthyroidism
    2. Grave's Disease
    3. Thyroid Storm
  2. Epidemiology
    1. Lifetime Prevalence (US): 0.5%
      1. Women: 2%
      2. Men 0.2%
      3. Turnbridge (1977) Clin Endocrinol 7:481
  3. Causes
    1. Stimulatory Causes (positive Radioactive Iodine scan)
      1. Grave's Disease (60-80% of hyperthyroidism cases)
      2. Trophoblastic Tumors activate TSH receptors via HCG (Choriocarcinoma)
      3. Pituitary TSH-secreting tumor
    2. Non-Stimulatory Causes
      1. Toxic Multinodular Goiter (5%)
      2. Toxic Thyroid Adenoma (Plummer's Disease)
      3. Exogenous Thyroid hormone source
      4. Thyroiditis
        1. Subacute Thyroiditis
        2. Acute Thyroiditis (Bacterial infection)
        3. Postpartum Thyroiditis (lymphocytic Thyroiditis)
      5. Tumors (rare)
        1. Metastatic follicular Thyroid Cancer
        2. Ovarian Cancer producing Thyroxine (struma ovarii)
      6. Medication-Induced Hyperthyroidism
        1. See Medications Affecting Thyroid Function
    3. Combined Stimulatory and Non-Stimulatory Causes (positive Radioactive Iodine scan)
      1. Nodular Goiter with superimposed stimulation
  4. Symptoms
    1. Nervousness or alertness
    2. Emotional lability (Anxiety, Irritability)
    3. Palpitations
    4. Insomnia
    5. Tremor
    6. Muscle Weakness
    7. Frequent Bowel Movements, Diarrhea
    8. Excessive Sweating
    9. Weight loss despite increased appetite
    10. Heat intolerance
    11. Oligomenorrhea or Amenorrhea
  5. Signs
    1. Anxious, restless, fidgeting patient
    2. Dermatologic
      1. Warm, moist and velvety
      2. Palmar erythema
      3. Hair fine and silky
      4. Fingernails
        1. Onycholysis (Plummer's Nails)
        2. Brown Nail Discoloration
    3. Neuromuscular
      1. Fine Tremor of fingers, Tongue
      2. Hyperkinesia
      3. Rapid speech
      4. Quadriceps weakness
    4. Eye changes
      1. Stare
      2. Widened palpebral fissures
      3. Infrequent blinking
      4. Chemosis
      5. Lid lag
      6. Proptosis (Exophthalmos)
      7. Periorbital edema
    5. Cardiovascular
      1. Increased Blood Pressure
        1. Systolic Hypertension
        2. Wide Pulse Pressure
      2. Arrhythmia
        1. Atrial Fibrillation
        2. Tachycardia
      3. Auscultation
        1. Loud S1 Heart Sound
        2. Loud S2 Heart Sound
        3. Systolic Murmur
      4. Cardiac hypertrophy
  6. Labs
    1. See Thyroid Function Testing
    2. Serum Thyroid Stimulating Hormone (TSH) suppressed
    3. Serum Free Thyroxine (Free T4) elevated
    4. Non-specific lab changes (variably present)
      1. Complete Blood Count (CBC)
        1. Anemia
        2. Granulocytosis and Lymphocytosis
      2. Electrolytes
        1. Hypercalcemia
      3. Liver Function Tests
        1. Liver transaminases (AST,ALT) increased
        2. Alkaline Phosphatase increased
  7. Diagnostics
    1. Thyroid Uptake Scan
      1. Differentiate hyperthyroidism causes
      2. Identify hot and cold Nodules
    2. Thyroid Ultrasound
      1. Differentiate solid from cystic Nodules
    3. If solid cold Nodule:
      1. Fine needle biopsy
      2. CT Head & Neck (evaluate for metestatic disease)
  8. Evaluation
    1. Step 1: Check TSH
      1. TSH Normal: No hyperthyroidism
      2. TSH Suppressed: Go to Step 2 below
      3. TSH Increased: Check Free T4
        1. Normal or Low: Consider Hypothyroidism
        2. Free T4 High: Secondary Hyperthyroidism (rare)
          1. Obtain MRI or CT of pituitary gland
    2. Step 2: Check Free T4 (for suppressed TSH)
      1. Free T4 High: Go to Step 3
      2. Free T4 Normal: Measure serum Free T3
        1. Normal T3: Follow for transient cause resolution
        2. Free T3 high: Go to Step 3
          1. T3 toxicosis (seen in 10-15% cases)
    3. Step 3: Thyroid Uptake Scan (Primary Hypothyroidism)
      1. Thyroid Uptake Scan with low uptake
        1. Single "Cold" Nodule: Possible Thyroid Cancer
        2. Diffusely low uptake: Go to Step 4
      2. Thyroid Uptake Scan with high uptake
        1. Diffusely high uptake: Grave's Disease
        2. Single "Hot" Nodule: Toxic Thyroid Adenoma
        3. Multiple "Hot" Nodules: Toxic Multinodular Goiter
    4. Step 4: Check Thyroglobulin (scan with low uptake)
      1. Thyroglobulin Low: Exogenous hormone source
      2. Thyroglobulin High
        1. Thyroiditis
        2. Ectopic Thyroid hormone production (e.g. ovary)
        3. Excess iodide exposure
  9. Management
    1. See Hyperthyroidism Management
  10. References
    1. Haddard (1998) Postgrad Med 104(1):42
    2. Hennessey (1996) Am Fam Physician 54(4):1315
    3. Reid (2005) Am Fam Physician 72:623
    4. Singer (1995) JAMA 273(10):808
    5. Slatosky (2000) Am Fam Physician 61(4):1047

Hyperthyroidism (C0020550)

Definition (MSH)Hypersecretion of THYROID HORMONES from the THYROID GLAND. Elevated levels of thyroid hormones increase BASAL METABOLIC RATE.
Definition (CSP)excessive functional activity of the thyroid gland.
Definition (NCI)Too much thyroid hormone. Symptoms include weight loss, chest pain, cramps, diarrhea, and nervousness.
ConceptsDisease or Syndrome (T047)
ICD9242.9
EnglishHyperthyroidism, Overactive Thyroid
Spanishhipertiroidismo
CreditsDerived from the NIH UMLS (Unified Medical Language System)


Thyrotoxicosis (C0040156)

Definition (MSH)A hypermetabolic syndrome caused by excess THYROID HORMONES which may come from endogenous or exogenous sources. The endogenous source of hormone may be thyroid HYPERPLASIA; THYROID NEOPLASMS; or hormone-producing extrathyroidal tissue. Thyrotoxicosis is characterized by NERVOUSNESS; TACHYCARDIA; FATIGUE; WEIGHT LOSS; heat intolerance; and excessive SWEATING.
ConceptsDisease or Syndrome (T047)
ICD9242, 242.9
EnglishThyrotoxicoses, Thyrotoxicosis, Thyrotoxicosis with or without goiter, Thyrotoxicosis with or without goitre
Spanishhipertiroidismo con o sin bocio, tirotoxicosis, tirotoxicosis con o sin bocio
CreditsDerived from the NIH UMLS (Unified Medical Language System)



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