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Thyroid Disorders

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Thyroid Disorders Eric J Milie, D.O. Objectives Understand basic interactions of the hypothalamic-pituitary-thyroid axis Recognize the various causes of hypo- and ... – PowerPoint PPT presentation

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Title: Thyroid Disorders


1
Thyroid Disorders
  • Eric J Milie, D.O.

2
Objectives
  • Understand basic interactions of the
    hypothalamic-pituitary-thyroid axis
  • Recognize the various causes of hypo- and
    hyperthyroid
  • Differentiate between acute, subacute, and
    chronic thyroiditis in terms of clinical picture
    and treatment
  • Explain the work-up required for a patient with a
    solitary thyroid nodule

3
Thyroid Anatomy
  • Small gland located in anterior portion of neck
  • Attached to larynx
  • Two halves (lobes) connected by isthmus
  • Resembles a butterfly or bow-tie
  • From Greek word meaning shield
  • Each lobe roughly 4cm long, 1-2cm wide
  • Cannot normally be seen, barely palpable in
    healthy adult

4
Thyroid Anatomy continued
5
Function of Thyroid Gland
  • Secretes thyroid hormones, which regulate
    metabolism throughout the body
  • Two hormones secreted Thyroxine (T4) and
    Triiodothyronine (T3)

6
Thyroid Hormones
  • T4, the major hormone produced by the thyroid,
    has only slight effect on controlling bodys
    metabolism
  • T4 converted to T3 (active thyroid hormone)
    mainly in the liver and kidney
  • Many factors effect conversion rate, including
    bodys need from moment to moment and presence or
    absence of illness

7
Chemical Structure
8
Thyroid Hormones continued
  • T4 de-iodinated in liver and kidney, resulting in
    T3 and reverse T3 (inactive)
  • Thyroid hormones poorly soluble in water, so 99
    protein bound
  • Principle carrier is thyroxine binding globulin,
    a glycoprotein synthesized by the liver

9
Some Thyroid Hormone Responsibilities
  • Heart rate
  • Respiratory rate
  • Rate of caloric consumption
  • Skin maintenance
  • Growth
  • Fertility
  • Digestion
  • Heat regulation

10
Role of Iodine
  • Chief component of thyroid hormones, essential
    for their production
  • Iodine concentrated from blood via the
    Sodium-iodide symporter, so-called iodine trap
  • In areas where there is not sufficient levels of
    iodine (Great Lakes, Swiss Alps, Tasmania),
    iodine must be supplimented
  • In U.S., salt iodized, so iodine deficiency is
    rare

11
Sodium-Iodine Symporter
12
Thyroid Stimulating Hormone
  • Chief stimulator of thryoid hormone synthesis is
    TSH (Thyroid Stimulating Hormone), released from
    anterior pituitary
  • Most important controller of TSH secretion is
    Thyrotropin Releasing Hormone (TRH) from
    hypothalamic neurons
  • Secretion of TRH, and hence TSH, inhibited by
    high blood levels of thyroid hormones (negative
    feedback loop)

13
TRH-TSH-Thyroid Hormone Feedback Loop
14
Hypothalamic-Pituitary Axis
  • Feedback loop pat of so-called hypothalamic
    pituitary axis
  • As thyroid hormone levels in blood increase,
    negative feedback to hypothalamus and pituitary
  • Leads to shut-down of thyroid producing follicles
  • When circulating levels of thyroid hormone
    stabilize, process begins anew
  • Axis influenced by other factors, including
    environmental factors (cold exposure leads to
    increase in thyroid hormone production in rodent
    models)

15
Hypothalamic-Pituitary-Thyroid Axis
16
Goiter Formation as Dysfunction of
Hypothalmic-Pituitary-Thyroid Axis
  • Insufficient dietary intake of iodine leads to
    insufficient production of T3 and T4
  • Hypothalamus responds with increasing levels of
    circulating TRH
  • Causes pituitary to release more TSH
  • Secondary function of TSH is thyroid cell growth
  • Prolonged exposure to high levels of TSH results
    in goiter

17
Goiter
18
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19
Thyroid Gland- Diagnostic Studies
  • No single test is 100 accurate in diagnosing
    thyroid disease, so usually combination of two or
    more tests ordered
  • TSH level is most common test ordered for
    monitoring of thyroid function
  • High levels of TSH usually indicative of under
    active thyroid gland (hypothyroid)
  • Low levels usually indicative of over active
    thyroid gland (hyperthyroid)

20
Diagnostic Tests continued
  • Measurement of T4 by radioimmunoassay (RIA)
    reflects the amount of T4 circulating in the
    blood.
  • Usually combined with T3 uptake to give a free
    T4 level, which corrects for other medications
    which influence the routine T4 test

21
Diagnostic Tests continued
  • Thyroid Binding Globulin may be ordered for
    patients with unexplained elevations or
    deficiency of T4 and T3
  • Excess or deficiency of TBG will alter the
    measurement of T3 and T4, but not the action of
    the hormones
  • Hereditary trait can cause excessive or deficient
    levels of TBG

22
Iodine Uptake Scan
  • Radioactive iodine administered to patient
  • Iodine concentrated in the thyroid or excreted in
    the urine
  • Uptake measured at various time intervals
  • Does not measure hormone levels, merely avidity
    of thyroid for iodine and clearance rate relative
    to kidney function
  • Diseases resulting in excessive production of
    thyroid hormone generally associated with
    increased RAIU, diseases resulting in decreased
    production generally show decreased RAIU

23
RAIU continued
24
Thyroid Scan
  • Usually done at same time as RAIU
  • Useful in identifying nodules and defining if
    they are hot or cold
  • Measuring size of goiter prior to treatment
  • Follow-up in thyroid cancer patients after
    surgery
  • Locating thyroid tissue outside of neck, such as
    at base of tongue or in the chest

25
Thyroid Scan
  • Two types, camera scan and Computerized
    Rectilinear Thyroid scan
  • Camera scan most common, takes 5-10 minutes
  • CRT developed in the 1990s, improves clarity,
    more precisely identifies nodules, and provides
    information on both function and size

26
Camera Scan
Camera scan images showing hot nodule (left)
and cold nodule (right)
27
CRT
28
Thyroid Ultrasound
  • Screening tool for suspected thyroid nodule
  • Can identify if nodule is cystic or solid, but
    provides little help determining if it is benign
    or malignant
  • Can detect changes in nodules size
  • Useful in assisting with needle biopsy of thyroid

29
Thyroid Ultrasound
30
Ultrasound Characteristics Suggesting Benign
Nodule
  • Sharp edges around entire nodule (well
    circumscribed)
  • Nodule filled with fluid and not live tissue
    (cystic)
  • Multiple nodules throughout the thyroid
  • No blood flowing through nodule on Doppler
    (suggest cystic lesion)

31
Fine Needle Biopsy
  • Most reliable test to determine whether cold
    nodule cancerous or benign
  • Provides definitive diagnosis in up to 75 of
    biopsies
  • Further discussion later in presentation

32
Euthyroid Sick Syndrome Definition
  • Clinical condition in which patients suffering
    from severe non-thyroid illness are clinically
    euthyroid but biochemically dysthyroid

33
Euthyroid Sick Syndrome Precipitating Factors
  • Fasting
  • Starvation
  • Anorexia nervosa
  • Protein malnutrition
  • Surgical trauma
  • Hyperthermia
  • Myocardial infarction
  • Chronic renal failure
  • Diabetic ketoacidosis
  • Cirrhosis
  • Sepsis

34
Euthyroid Sick Syndrome Lab Findings
  • T4 concentration is normal or decreased
  • T4-binding to TBG is decreased
  • T3 concentration is decreased
  • rT3 concentration is increased
  • TSH concentration is normal
  • Thyroid scans usually normal

35
Euthyroid Sick Syndrome Pathogenesis
  • When people are sick or malnourished or have had
    surgery, the thyroid hormone T4 is not converted
    normally to the active T3 hormone
  • Large amounts of reverse T3 accumulate
  • Despite this abnormal conversion, the thyroid
    functions normally
  • No treatment is necessary, as thyroid function is
    preserved
  • Laboratory tests normalize once the underlying
    illness resolves

36
Hyperthyroid Definition
  • Condition of excess functional activity of the
    thyroid gland
  • Characterized by increased basal metabolism,
    goiter, and disturbances of the autonomic nervous
    system
  • Affects women 31 more than men

37
Hyperthyroid Types
  • Graves disease
  • Toxic nodular goiter (Plummers disease)
  • Toxic adenoma
  • Therapeutic induced hyperthyroid (Lugols,
    amiodarone, etc.)
  • Thyroiditis
  • Primary and/or metastatic follicular carcinoma
  • TSH producing tumor of the hypophysis

38
Hyperthyroid Common Symptoms and Signs
  • Heat intolerance, excessive sweating, and moist
    skin
  • Hyperactivity and tenseness
  • Weight loss (unintentional)
  • Fine tremors, palpitations, and tachycardia
  • Infiltrative dermopathy
  • Ocular signs, including lid lag, exophthalmus,
    and conjunctival injection
  • Generalized pruritis

39
Hyperthyroid Diagnostic Work-up
  • History and physical
  • Blood chemistries, including hormone levels and
    specific antibodies
  • Ultrasound
  • Thyroid scan
  • Fine needle biopsy (particularly with
    hyperthyroidism associated with nodularity)

40
Graves Disease
  • Autoimmune disease associated with the production
    of antibodies that bind to TSH receptors in the
    follicular cells of the thyroid and activate
    these cells to produce T4 and T3.
  • These antibodies therefore simulate TSH - TSH has
    no part in this hyperfunctioning

41
Graves Disease Pathophysiology
  • Most common form of adult hyperthyroidism
  • Peaks in 3rd and 4th generations
  • Clinical presentation includes all aforementioned
    signs and symptoms ocular and dermatological
    signs pathognomonic
  • Bilateral exophthalmos occurs in 40-50 of
    Graves patients- unilateral involvement is rare

42
Graves Disease continued
  • T3 and T4 concentrations increased
  • TSH level decreased
  • Autoimmune antibodies to TSH receptors
  • RAI and Tc-99m studies are increased
  • Scans usually show mildly enlarged thyroid which
    concentrates isotope evenly and intensely

43
Graves Disease- Therapy (Conservative)
  • Treatment with antithyroid drugs (Propranolol,
    propylthiouricil, methimazole)
  • Long term remission rate with conservative
    treatment is low (30-50)
  • Propranolol ß-blocker makes patient eumetabolic
    but not euthyroid
  • Other drugs block iodothyronine hormone synthesis

44
Graves Disease- Therapy Surgery
  • Treatment of choice if patient younger than 21
    years of age, is sensitive to iodine, or who have
    very large goiters
  • In good hands, recurrence rate is low (2-9)with
    a 3 incidence of hypothyroidism
  • Side effects vocal cord paralysis and
    hypoparathyroidism

45
Graves Disease- Therapy Radioactive Iodine-131
  • Therapy of choice for women past childbearing
    years and adult males
  • No proven increase in incidence of carcinoma,
    leukemia, etc.
  • 25 of patients will be hypothyroid one year
    after treatment incidence increases 2/year for
    the next 20 years

46
Graves Ophthalmopathy
  • Most frequent extrathyroidal manifestationof
    Graves disease
  • Fortunately, most patients with only minor
    involvement, amenable to non-aggressive treatment

47
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48
Graves Exophthalmos Picture
49
Management of Nonsevere Exophthalmos
Management of nonsevere Graves ophthalmopathy13 Management of nonsevere Graves ophthalmopathy13
Sign and/or symptom Therapeutic measure
Photophobia Foreign body sensation Eyelid retraction increased intraocular pressure Lag ophthalmos Mild diplopia Sunglasses Artificial tears and ointments ß-Blocking eyedrops Nocturnal taping of the eyes Prisms Correction of hyper- or hypothyroidism Elimination of risk factors (smoking) Reassurance on the natural history of the disease
50
Management of Severe Exophthalmos
Management of severe Graves ophthalmopathy13
Established methods Glucocorticoidsa. Oralb. Intravenousc. Local Supervoltage orbital radiotherapy a. Rehabilitative surgeryb. Orbital decompressionc. Extraocular muscle surgeryd. Eyelid surgery Novel treatments under investigation 1. Somatostatin Analogues 2. Octreotide 3. Lanreotide 4. Intravenous immunoglobulins 5. Nonestablished methods 6. Cyclosporinea 7. Plasmapheresis 8. Anecdotal treatments 9. Cyclophosphamide 10. Bromocriptine 11. Metradinazole
51
Infiltrative Dermopathy of Graves Disease
52
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53
Toxic Adenoma Definition
  • Autonomous hyperfunctioning nodule surrounded by
    normal functioning tissue
  • Rarely two or more adenomas exist in normally
    functioning thyroid
  • No clear cause neither antibodies nor TSH
    involved
  • Nodule must be 2.5-3cm in size to produce
    hyperthyroidism

54
Toxic Adenoma Presentation
  • Symptoms and signs of hyperthyroidism.
  • No exophthalmos.
  • No infiltrating dermopathy.
  • The thyroid gland may be enlarged, but is
    generally of normal size.
  • On palpation, a non-tender, mildly firm nodule is
    palpable.

55
Toxic Adenoma Diagnosis
  • T3 and T4 levels are elevated.
  • The TSH concentration is decreased.
  • Specific antibodies are absent.
  • On Radioisotope scan, the thyroid gland is
    usually of normal size.
  • One hot nodule - rest of the gland is cool

56
Toxic Adenoma Treatment
  • Unless contraindicated, radioactive iodine (131I)
    - higher doses are usually necessary.
  • Production of hypothyroidism is rare.

57
Toxic Adenoma Imaging
58
Toxic Multinodular Goiter (Plummers Disease)
  • enlarged multinodular goiter commonly found in
    areas of iodine deficiency in which patients with
    long-standing non-toxic goiter develop
    thyrotoxicosis
  • One or more of the nodules begin to hyperfunction
    autonomously
  • Encompasses a spectrum of different clinical
    entities ranging from a single hyperfunctioning
    nodule within an enlarged thyroid gland having
    additional non-functioning nodules to multiple
    hyperfunctioning areas (nodules) scattered
    throughout the gland barely distinguishable from
    non-functioning nodules and ordinary thyroid
    tissue

59
Plummers Disease Clinical Presentation
  • A middle-aged person with 10 - 15 years history
    of an enlarged gland.
  • The general symptoms and signs of
    hyperthyroidism.
  • Exophthalmos is absent.
  • Infiltrative dermopathy is absent.
  • The gland is enlarged and multinodular.

60
Plummers Disease Diagnosis
  • The serum T3 and T4 levels are raised.
  • The TSH concentration is decreased.
  • No auto-immune antibodies are present
  • Scan shows an enlarged, multinodular gland.
  • One, two or more nodules are hot (overactive) and
    in between cool and cold nodules

61
Plummers Disease Treatment
  • Similar to treatment for Graves disease
  • Plummers disease is more resistant to 131I
    therapy than Graves - apparently because the
    areas (nodules) of low activity at the time of
    therapy become active as the hyperactive nodules
    are destroyed and more TSH is released.
  • Induction of hypothyroidism is rare

62
Plummers Disease Imaging
63
Thyrotoxicosis Factitiae
  • syndrome of hyperthyroidism that results from an
    overdosage of thyroid hormone - T3 or T4.
  • Clinical signs and symptoms similar to other
    causes of hyperthyroidism
  • No exophthalmos or dermopathy

64
Thyrotoxicosis Factitiae Diagnosis
  • T3 therapy serum concentration of T3 is
    increased, serum T4 is decreased, and TSH
    concentration is decreased.
  • T4 therapy serum T3 concentration is increased,
    T4 concentration is increased, TSH level is
    decreased.
  • RAI uptake by thyroid is decreased
  • The thyroid gland is not enlarged.
  • Scan image shows a cool thyroid

65
Thyrotoxicosis Factitiae Treatment
  • Reduce or suspend T4 therapy.
  • Normalization may take 6 weeks or longer

66
Hamburger Thyrotoxicosis
  • Several outbreaks of thyrotoxicosis have been
    attributed to a practice, now banned in the US,
    called "gullet trimming
  • Meat in the neck region of slaughtered animals is
    ground into hamburger
  • Thyroid glands are reddish in color and located
    in the neck, it's not unusual for gullet trimmers
    to get thyroid glands into hamburger or sausage
  • Outbreak of thyrotoxicosis in Minnesota and South
    Dakota that was traced to thyroid-contaminated
    hamburger. A total of 121 cases were identified
    in nine counties, with the highest incidence in
    the county having the offending slaughter plant.
    The patients complained of sleeplessness,
    nervousness, headache, fatique, excessive
    sweating and weight loss

67
Iodine-precipitated Hyperthyroidism
  • With iodine deficiency production of T4 and T3
    decreases, so more TSH is released and thyroid
    stimulation increases, resulting in enlargement
    of the thyroid (goiter)
  • If iodine intake is increased in such a patient
    the enlarged gland may produce excess amounts of
    T3 and T4, and hyperthyroidism develops.
  • Excess iodine intake by euthyroids and
    hyperthyroids may suppress TSH secretion and thus
    produce hypothyroidism or it may produce
    hyperthyroidism by activating hormogenesis in
    patients with deranged special thyroidal systems,
    so-called Jod-Basedow phenomenon
  • Lastly, it may elicit hyperactivity in normal
    thyroid glands by deranging the function of the
    cells

68
Secondary Hyperthyroidism
  • This term refers to hyperthyroidism precipitated
    by excess TSH secretion by a pituitary tumour or
    by other tumours (e.g. choriocarcinoma, struma
    ovarii, etc.)
  • Clinical signs and symptoms same as other causes
    of hyperthyroidism, without exophthalmos
  • The T3, T4 and TSH concentrations are raised
  • The thyroid is enlarged and the isotope uptake is
    diffusely increased.

69
Hypothyroidism
  • condition where insufficient thyroid hormones are
    produced
  • Two main types are distinguished,. primary and
    secondary hypothyroidism
  • Primary hypothyroidism by far more common
  • Primary Hypothyroidism can be subdivided into
    hypothalamic-pituitary causes vs. thyroidal causes

70
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71
Hypothyroidism Causes Primary
1. Primary (thyroidal) hypothyroidism          
1. Loss of functional thyroid tissue
                    1. chronic autoimmune
thyroiditis                     2. reversible
autoimmune hypothyroidism (silent and postpartum
thyroiditis, cytokine-induced thyroiditis).
                    3. surgery and irradiation
(131I or external irradiation)                   
  4. infiltrative and infectious diseases,
subacute thyroiditis                     5.
thyroid dysgenesis           2. Functional
defects in thyroid hormone biosynthesis and
release                     1. congenital
defects in thyroid hormone biosynthesis
                    2. iodine deficiency and
iodine excess                     3. drugs
antithyroid agents, lithium, natural and
synthetic goitrogenic chemicals
72
Hypothyroidism Causes Secondary
2. Central (hypothalamic/pituitary) hypothyroidism           1. Loss of functional tissue                     1. tumors (pituitary adenoma, craniopharyngioma, meningioma, dysgerminoma, glioma, metastases)                    2. trauma (surgery, irradiation, head injury)                     3. vascular (ischemic necrosis, hemorrhage, stalk interrruption, aneurysm of internal carotid artery)                     4. infections (abcess, tuberculosis, syphilis, toxoplasmosis)                     5. infiltrative (sarcoidosis, histiocytosis, hemochromatosis)                     6. chronic lymphocytic hypophysitis                     7. congenital (pituitary hypoplasia, septooptic dysplasia, basal encephalocele)           2. Functional defects in TSH biosynthesis and release                     1. mutations in genes encoding for TRH receptor, TSHß, or Pit-                     2. drugs dopamine glucocorticoids L-thyroxine withdrawal 3. "Peripheral" (extrathyroidal) hypothyroidism                     1. Thyroid hormone resistance                    2. Massive infantile hemangioma

73
Hypothyroidism Signs and Symptoms
  • A dull facial expression, a hoarse voice, slow
    speech, a puffed face with swollen periorbital
    tissues. These changes are the result of
    mucopolysaccharide (hyaluronic acid and
    chondroitin sulphate) infiltration of the
    tissues.
  • The patient is cold-intolerant due to low
    metabolic rate.
  • Drooped eyelids and the hair is sparse the skin
    is coarse, dry, scaly and thick.
  • Modest weight gain.
  • Signs of intellectual impairment - frank
    psychosis (myxoedema madness) may develop.
  • A yellowish colour of the skin due to
    carotenaemia, and pruritis.11
  • Bradycardia, cardiac arrhythmia, etc.

74
Hypothyroid Lab Studies
  • Anemia normo-/micro-/macrocytic.
  • T4 and T3 concentrations are low, and TSH
    concentration is high in the primary type.
  • T4, T3 and TSH are low in the secondary type.
  • TRH and/or TSH tests differentiate between
    primary and secondary hypothyroidism.

75
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76
Thyroiditis
  • Inflammation of the thyroid gland
  • Classified as chronic, subacute, and acute
  • Can initially present as hyperthyroidism,
    ramification may result in hypothyroidism

77
Hashimotos Thyroiditis
  • A chronic inflammation of the thyroid with
    lymphocytic infiltration of the gland caused by
    autoimmune factors
  • Most common cause of primary hypothyroidism in
    North America
  • Women to men 81, rate increases in both sexes
    with age
  • A family history of thyroid disorders is common,
    and incidence is increased in patients with
    chromosomal disorders, including Turner's, Down,
    and Klinefelter's syndromes

78
Hashimotos Signs and Symptoms
  • Painless enlargement of the thyroid gland
  • Examination reveals a nontender goiter, smooth or
    nodular, firm, and more rubbery than the normal
    thyroid many patients have hypothyroidism when
    first seen
  • Other forms of autoimmune disease are common
  • There may be an increased incidence of thyroid
    neoplasia, particularly papillary carcinoma and
    thyroid lymphoma

79
Hashimotos Diagnosis
  • Laboratory findings early in the disease consist
    of normal T4 and TSH levels and high titers of
    thyroid peroxidase antibodies and less commonly
    anti-thyroglobulin antibodies
  • The thyroid radioactive iodine uptake may be
    increased, perhaps because of a defect in
    organification of iodide in conjunction with a
    gland that continues to trap iodine
  • Later in the disease, the patient develops
    hypothyroidism with decreased T4, decreased
    thyroid radioactive iodine uptake, and increased
    TSH

80
Hashimotos Treatment
  • usually requires lifelong replacement therapy
    with thyroid hormone to decrease goiter size and
    treat the hypothyroidism
  • Occasionally, the hypothyroidism is transient
  • The average oral replacement dose with
    L-thyroxine is 100-120 µg/day

81
Hashimotos
82
Subacute Thyroiditis (de Quervains Thyroiditis)
  • Acute inflammatory disease of the thyroid,
    probably caused by a virus
  • Frequently a history of mumps
  • The gland shows giant cell infiltration but
    lymphocyte infiltration is absent
  • Female patients outnumbered male patients in a
    ratio of 3-61
  • Although the disease has been described at all
    ages, it is rare in children

83
Subacute Thyroiditis Presentation
  • Condition is characterized by sudden onset of
    sore throat, tenderness of the neck and low grade
    fever
  • Disease may reach its peak within 3 to 4 days and
    subside and disappear within a week, but more
    typically, a gradual onset extends over 1 to 2
    weeks and continues with a fluctuating intensity
    for 3 to 6 weeks
  • Thyroid gland is typically enlarged two or three
    times the normal size or larger and is tender to
    palpation
  • The condition is often confused with pharyngitis
    or otitis media

84
Subacute Thyroiditis Presentation continued
  • Approximately one-half of the patients present
    during the first weeks of the illness, with
    symptoms of thyrotoxicosis, including
    nervousness, heat intolerance, palpitations,
    tremulousness, and increased sweating
  • As the disease process subsides, transient
    hypothyroidism occurs in about one-quarter of the
    patients
  • Ultimately thyroid function returns to normal and
    permanent hypothyroidism occurs in less than 10
    percent of the cases

85
Subacute Thyroiditis Diagnosis
  • History and clinical examination.
  • An elevated erythrocyte sedimentation rate.
  • The T4 level is elevated, the TSH is down.
  • The 131I-uptake is down in the presence of
    elevated T4, and a radioisotope scan (99mTcO4-)
    shows a cool thyroid or the thyroid is not
    visualized.

86
Subacute Thyroiditis Treatment
  • In some instances, no treatment is required
  • Mainstay of treatment is analgesia
  • Initial therapy with Aspirin or NSAIDs
  • May need to treat with corticosteroids
    (Typically, Prednisone 40mg daily to begin with,
    followed by a long taper of up to six weeks)
  • Relief of symptoms with treatment almost
    diagnostic
  • Alternatively oral cholecystographic agents (such
    as sodium ipodate or sodium iopanoate) may be
    used safely and effectively for the management of
    hyperthyroidism in these patients even when they
    have relapsed after corticosteroid therapy
  • The recurrent rate of subacute thyroiditis after
    cessation of prednisone therapy is about 20 but
    no difference has been found in routine
    laboratory data between recurrent and
    non-recurrent groups of patients
  • Levothyroxine administration may be useful in
    situations where the patient is not already
    hyperthyroid due to the release of thyroidal
    contents into the circulation

87
Subacute Thyroiditis Prognosis
  • In 90 or more of patients, there is a complete
    and spontaneous recovery and a return to normal
    thyroid function
  • However, the thyroid glands of patients with
    subacute thyroiditis may exhibit irregular
    scarring between islands of residual functioning
    parenchyma, although the patient has no symptom
  • Up to 10 of the patients may become hypothyroid
    and require permanent replacement with
    levothyroxine

88
Acute (Infectious) Thyroiditis
  • Thyroid extremely resistant to infection,
    therefore infectious thyroiditis rare
  • However, in certain situations, particularly in
    children a persistent fistula from the pyriform
    sinus may make the left lobe of the thyroid
    particularly susceptible to abscess formation
  • Occasionally, acute bacterial supporative
    thyroiditis occurs in children receiving cancer
    chemotherapy

89
Acute Thyroiditis Etiology
  • Virtually any bacteria can infect the thyroid
  • Strep, Staph, pneumococcus, salmonella,
    bacteroides, t. pallidum, pasturella, and
    mycobacterium all documented
  • In addition, fungal infections, including
    cryptococcus, have been reported
  • Most commonly, however, especially in children,
    infection of the thyroid gland is a result of
    direct extension from an internal fistula from
    the pyriform sinus

90
Acute Thyroiditis Etiology
91
Acute Thyroiditis Presentation
  • The dominant clinical symptom is pain in the
    region of the thyroid gland which may
    subsequently enlarge and become hot and tender
  • The patient is unable to extend the neck and
    often sits with the neck flexed in order to avoid
    pressure on the thyroid gland
  • Swallowing is painful
  • There are usually signs of infection in
    structures adjacent to the thyroid, local
    lymphadenopathy as well as temperature elevation
    and, if bacteremia occurs, chills
  • Gas formation has been noted with suppurative
    thyroiditis
  • Pediatric presentation more typical than adult
  • In general, no sign of hypo- or hyperthyroidism

92
Acute Thyroiditis Diagnosis
  • History, physical, and clinical suspicion most
    important
  • Patient more ill appearing than in subacute
  • The T3, T4 and TSH levels are usually normal, and
    the rT3 is increased
  • A radioisotope scan shows an enlarged gland with
    diffusely increased isotope uptake
  • If lesion localized on ultrasound or scan, needle
    biopsy diagnostic

93
Acute Thyroiditis Treatment
  • Surgical removal of fistulous tract in pediatric
    patients with communication with pyriform sinus
  • Systemic antibiotics with broad spectrum coverage
    needed for some patients
  • Must add fungal coverage in immunocompromised
    patients

94
Acute Thyroiditis Prognosis
  • some patients with thyroiditis, the destruction
    may be sufficiently severe that hypothyroidism
    results
  • Patients with a particularly diffuse thyroiditis
    should have follow-up thyroid function studies
    performed to determine that this has not occurred
  • Surgical removal of a fistula or branchial pouch
    sinus is required to prevent recurrence when this
    is present

95
Clinical Differences Between Thyroiditis Types
Subtype Etiology Neck Pain RAIU TSH T4 Autoantibodies
Chronic lymphocytic (Hashimoto's disease) Autoimmune No Present
Subacute granulomatous Viral Yes ? ? ? Absent
Microbial inflammatory Bacterial, fungal, parasitic Yes Normal Normal Absent
96
Amiodarone and Thyroid
  • Amiodarone used to treat cardiac arrythmias
  • Structurally similar to thyroid hormone,
    comprised of 39 iodine
  • Patients on amiodarone may become hypo- or
    hyperthyroid
  • If hypothyroid, stop amiodarone and give T4

97
Amiodarone Induced Hyperthyroid
  • Two Types Type I and Type II
  • Type 1 In this type underlying thyroid pathology
    is present, for example multinodular or diffuse
    goiter (thyroid enlarged) and in these patients
    amiodarone precipitates typical Jod-Basedow with
    increased blood T4 and T3 levels and a decreased
    blood TSH level
  • Radioisotope studies show a diffusely or
    multinodular enlarged gland (goiter) with normal
    or increased 131I or 99mTc uptake
  • Ultrasound shows a nodular or enlarged thyroid
    gland
  • Improves with use of perchlorate, which promotes
    iodine expulsion from thyroid

98
Amiodarone Induced Hyperthyroid continued
  • Type II In this type there is no evidence of
    underlying thyroid pathology
  • The gland is small and it may be tender
  • Radioisotope studies (131I or 99mTc) show a small
    gland with low or absent radioisotope uptake
  • Ultrasound images are normal
  • The onset of the condition is often explosive
  • The condition is treated by steroids, in addition
    to perchlorate

99
Thyroid Nodule
  • One in 12 to 15 young women has a thyroid nodule
  • One in 40 young men has a thyroid nodule
  • More than 95 percent of all thyroid nodules are
    benign (non-cancerous growths)
  • Some are actually cysts which are filled with
    fluid rather than thyroid tissue
  • Most people will develop a thyroid nodule by the
    time they are 50 years old
  • The incidence of thyroid nodules increases with
    age
  • 50 of 50 year olds will have at least one
    thyroid nodule
  • 60 of 60 year olds will have at least one
    thyroid nodule
  • 70 of 70 year olds will have at least one
    thyroid nodule

100
Thyroid Nodule continued
  • Ninety-five percent of solitary thyroid nodules
    are benign
  • Thyroid cancers typically present as a dominant
    solitary thyroid nodule, cold nodule on scan
  • Papillary carcinoma accounts for 60 percent,
    follicular carcinoma accounts for 12 percent, and
    the follicular variant of papillary carcinoma
    accounting for six percent
  • Fine needle biopsy is a safe, effective, and easy
    way to determine if a nodule is cancerous

101
Features Favoring Benign Nodule
  • Family history of Hashimoto's thyroiditis
  • Family history of benign thyroid nodule or
    goiter
  • Symptoms of hyperthyroidism or hypothyroidism
  • Pain or tenderness associated with a nodule
  • Soft, smooth, mobile nodule
  • Multinodular goiter without a predominant nodule
    (lots of nodules, not one main nodule)
  • Warm" nodule on thyroid scan (produces normal
    amount of hormone)
  • Simple cyst on ultrasound

102
Factors Favoring Malignant Nodule
  • Age less than 20
  • Age greater than 70
  • Male gender
  • New onset of swallowing difficulties
  • New onset of hoarseness
  • History of external neck irradiation during
    childhood
  • Firm, irregular and fixed nodule
  • Presence of cervical lymphadenopathy (swollen
    hard lymph nodes in the neck)
  • Previous history of thyroid cancer
  • Nodule that is "cold" on scan (shown in picture
    above, meaning the nodule does not make hormone)
  • Solid or complex on ultrasound

103
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104
Thyroid Disease Review
Condition TSH Free T4 Free T3 Other
Graves Disease ??? ? Usually ? Thyroid scan with diffuse isotope uptake
Toxic Adenoma ? ? or Normal ? or Normal thyroid scan shows functioning nodule and suppression of other thyroid tissue
Toxic Multi-nodular Goiter ? ? or Normal ? or Normal thyroid scan shows enlarged gland with multiple active nodules
Thyroiditis ? Variably ? Variably ? thyroid scan shows low radioiodine uptake, thyroglobulin level markedly raised.
Factitious Hyper-thyroidism ? ? ? or Normal low radioiodine uptake on thyroid scan and absent thyroglobulin levels
Pregnancy Normal ? total T4 Normal free T4 ? total T3 Norma free T3 positive pregnancy test
Steroid therapy, Severe Illness, etc. Normal or ? Normal Normal N/A
105
Question 1
  • A 60 year old woman comes to your clinic for
    examination of a lump in her neck. On physical
    examination, a soft, smooth, mobile nodule is
    palpated in the left lobe of the thyroid.
    Thyroid scan ordered through your clinic shows a
    1cm hot nodule at the superior pole of the left
    thyroid lobe. Which of the following should you
    tell your patient when she asks about the results
    of her tests?
  • A. This lesion most likely represents cancer and
    an urgent surgical referral must be sought
  • B. Lesions such as these are exceedingly rare in
    patients her age
  • C. 95 of these lesions are benign
  • D. She most likely has an infection of the
    thyroid and will require inpatient antibiotic
    therapy

106
Question 2
  • A 35 year old African American female presents to
    your clinic with a two week history of
    palpitations, excessive sweating, and a recent 15
    pound weight loss, though she is always eating.
    Also, she notices that the front of her neck is
    fuller than usual and her eyes bug-out. She
    has a history of Lupus, but has otherwise been
    healthy. Routine laboratory tests are ordered.
    Which of the following would you expect to find?
  • A. Elevated level of TSH
  • B. Decreased level of T4
  • C. Decreased level of T3
  • D. Auto-antibodies to TSH receptors
  • E. Anti-thyroglobulin antibodies

107
Question 3
  • While working in the Emergency Department of a
    local community hospital, a five year old boy is
    brought in by his parents because of a sore
    throat. The child has leukemia, and has received
    chemotherapy for the same two weeks prior to his
    presentation. On exam, the child appears
    lethargic. There is a noticeably enlarged lump
    in the area of the left lobe of the thyroid
    gland, which elicits a painful response when
    palpated. Upon further questioning, the parents
    state that he hasnt eaten well over the past 2-3
    days because of difficulty swallowing. Which of
    the following is the most likely diagnosis?
  • A. Acute infectious thyroiditis
  • B. Sick Euthyroid Syndrome
  • C. Hamburger Thyrotoxicosis
  • D. Hashimotos Thyroiditis
  • E. Plummers Disease

108
References
  • American Association of Clinical Endocrinologists
    medical guidelines for clinical practice for the
    evaluation and treatment of hyperthyroidism and
    hypothyroidism. Endocr Pract. 2002
    Nov-Dec8(6)457-69
  • Bartalena L. Pinchera A, Macocci C. Management of
    Graves ophthalmopathy Reality and
    prespectives. Endocrine Reviews 2000 21168-199.
  • Beers, Mark MD et al. The Merck Manual of
    Diagnosis and Therapy Seventh Edition. Merck,
    New York, 1995
  • Braunwald, et al. Harrisons Principals of
    Internal Medicine, 15th Edition. McGraw, New
    York. 2001.
  • Klopper JF. Diagnosis and management of
    amiodarone-induced hyperthyroidism. SA Med J
    1999 89453-454.
  • Murray IPC and Ell PJ. (1998) Nuclear Medicine in
    Clinical Diagnosis and T reatment. 2nd Ed.
    Churchill Livingstone, Edinburgh 136-142.
  • O'Reilly DS Thyroid function tests-time for a
    reassessment.BMJ 2000 May 13320(7245)1332-4.
  • Student BMJ . Interpreting Thyroid Function
    Tests. 
  • www.emedicine.com
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