Transcript 02 Hypothyroidism

Nursing 870
Hypothyroidism
 Hypothyroidism is a common endocrine disorder
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resulting from deficiency of thyroid hormone
Usually a primary process, thyroid gland is unable
to produce sufficient amounts of thyroid hormone
Can be secondary, the thyroid gland is normal, but
it receives insufficient stimulation because of low
secretion of thyrotropin (ie, thyroid-stimulating
hormone [TSH]) from the pituitary gland
May be iatrogenic, drug induced
May be congenital
Hypothyroidism: Causes
 Lack of iodine: most common in the world
 Autoimmune: most common in the US
 Hashimoto’s thyroiditis
Thyroid Screening
 No universal recommendation
 The American Thyroid Association
 Screening at age 35 years and every 5 years
 More frequent if at high risk
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Pregnant women
Women older than 60 years
Patients with type 1 diabetes or other autoimmune disease
Patients with a history of neck irradiation
Thyroid Screening
 The American College: screening women older
than 50, with 1 or more clinical features of
disease
 The American Academy of Family Physicians:
screening asymptomatic patients older than 60
years
 The American Association of Clinical
Endocrinologists: recommends TSH
measurements in all women of childbearing age
before pregnancy or during the first trimester
 The US Preventive Task Force concludes that
the evidence is insufficient to recommend for or
against routine screening for thyroid disease in
adults
PollEv:
 A TSH of 40 is consistent with
 Hyper  Or Hypo – thyroidism?
Hypothyroidism: Patho
Hypothyroidism: Patho
 Early in the disease process, compensatory
mechanisms maintain T3 levels
 Decreased production of T4 causes an increase in the
secretion of TSH by the pituitary gland
 TSH stimulates hypertrophy and hyperplasia of the
thyroid gland and 5’-deiodinase activity, thereby
increasing T3 production.
Hypothyroidism: Patho
 CV
 Decreased contractility
 Cardiac enlargement
 Pericardial effusion
 Decreased pulse,
 Decreased cardiac output
 GI tract changes
 Achlorhydria
 Prolonged intestinal transit time
 Gastric stasis
 GYN
 Delayed puberty
 Anovulation
 Menstrual irregularities,
 Infertility are common. TSH screening should be a routine part of
any investigation into menstrual irregularities or infertility.
Hypothyroidism: Patho
 Can cause
 Increased levels of total cholesterol
 Increased LDL
 Decreased HDL because of a change in metabolic
clearance. In addition
 Increase in insulin resistance.
Hypothyroidism: Etiology
 Primary hypothyroidism
 Chronic lymphocytic (autoimmune) thyroiditis
 Postpartum thyroiditis
 Subacute (granulomatous) thyroiditis
 Drug-induced hypothyroidism
 Iatrogenic hypothyroidism
 Genetic
 Iodine deficiency or excess
Hypothyroidism: Etiology
 Central hypothyroidism (secondary or tertiary)
 Results when the hypothalamic-pituitary axis is
damaged
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Pituitary adenoma
Tumors impinging on the hypothalamus
Lymphocytic hypophysitis
Sheehan syndrome
History of brain or pituitary irradiation
Drugs (eg, dopamine, prednisone, or opioids)
Congenital nongoiterous hypothyroidism type 4
TRH resistance
TRH deficiency
Hypothyroidism: Epidemiology
 The National Health and Nutrition Examination
Survey (NHANES 1999-2002) of 4392 individuals
reflecting the US population reported hypothyroidism
(defined as TSH levels exceeding 4.5 mIU/L) in 3.7% of
the population
 The WHO data from 130 countries found inadequate
iodine nutrition in 30.6% of the population.
Hypothyroidism: Epidemiology
 Age
 Frequency of hypothyroidism, goiters, and thyroid
nodules increases with age
 Most prevalent in elderly populations, with 2-20% of
older age groups having some form of hypothyroidism
 The Framingham study found hypothyroidism (TSH >
10 mIU/L) in 5.9% of women and 2.4% of men older
than 60 years
Hypothyroidism: Epidemiology
 Gender
 More common in females (2-8 times higher)
 Race
 Higher in whites (5.1%) and Mexican Americans than in
African Americans (1.7%)
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African Americans tend to have lower median TSH values.
PollEv:
 Name a symptom of hypothyroidism:
Hypothyroidism: Symptoms
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Fatigue, loss of energy, lethargy
Weight gain
Decreased appetite
Cold intolerance
Dry skin
Hair loss
Sleepiness
Muscle pain, joint pain, weakness in the extremities
Depression
Emotional lability, mental impairment
Forgetfulness, impaired memory, inability to concentrate
Constipation
Menstrual disturbances, impaired fertility
Decreased perspiration
Paresthesias, nerve entrapment syndromes
Blurred vision
Decreased hearing
Fullness in the throat, hoarseness
Myxedema Coma
 A severe form of hypothyroidism that results in
 An altered mental status
 Hypothermia
 Bradycardia
 Hypercarbia
 Hyponatremia
 Cardiomegaly, pericardial effusion, cardiogenic shock,
and ascites may be present
Hypothyroidism: PE
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Weight gain
Slowed speech and movements
Dry skin
Jaundice
Pallor
Coarse, brittle, straw-like hair
Loss of scalp hair, axillary hair, pubic hair, or a combination
Dull facial expression
Coarse facial features
Periorbital puffiness
Macroglossia
Goiter (simple or nodular)
Hypothyroidism: PE
 Hoarseness
 Decreased systolic blood pressure and increased
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diastolic blood pressure
Bradycardia
Pericardial effusion
Abdominal distention, ascites (uncommon)
Hypothermia (only in severe hypothyroid states)
Nonpitting edema (myxedema)
Pitting edema of lower extremities
Hyporeflexia with delayed relaxation, ataxia, or both
Hypothyroidism: Differential
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Anemia
Autoimmune thyroid disease
Goiter
Myxedema
Subacute
Thyroid lymphoma
Iodine deficiency
Addison’s disease
Anovulation
Sleep apnea
Hypothyroidism: Differential
 Cardiac tamponade
 Chronic fatigue syndrome
 Constipation
 Depression
 Dysmenorrhea
 Many other considerations related to symptoms
Hypothyroidism: Diagnostics
 TSH
 Normal accepted as 0.40-4.2 mIU/L
 Generally the most sensitive screening tool for primary
hypothyroidism
 Less expensive than other tests
 Rapid turn around time
 T4
 Generally obtained if TSH is above normal
 More expensive than TSH
 Takes longer for results
Hypothyroidism: Diagnostics
 Primary hypothyroidism
 Elevated TSH levels and decreased T4
 If elevated TSH levels (usually 4.5-10.0 mIU/L) but
normal T4, considered to have mild or subclinical
hypothyroidism
Hypothyroidism: Diagnostics
 Assays for anti–thyroid peroxidase (anti-TPO) and
antithyroglobulin (anti-Tg) antibodies
 May be helpful in determining the etiology of
hypothyroidism or in predicting future hypothyroidism
Hypothyroidism
 Overt hypothyroidism
 Diagnosis when TSH >10 with a subnormal free T4
 Subclinical hypothyroidism
 TSH above normal limit, with a normal free T4
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Only if no severe illness and if normal hypothalamic, pituitary
axis
Hypothyroidism: Diagnostics
 CBC: may show anemia
 Electrolytes: may show dilutional hyponatremia
 Lipid levels may be elevated
 Creatinine may be elevated (reversible)
 Liver function and creatinine kinase elevations have
been found
Hypothyroidism: Diagnostics
 US: used to detect nodules and infiltrative disease
 Fine needle aspiration: Procedure of choice for
evaluating suspicious nodules
 5-15% of solitary nodules are cancerous
Hypothyroidism: Treatment
 Treat any underlying disorder
 Thyroid replacement (levothyroxine)
 For most cases of mild to moderate hypothyroidism, a
starting levothyroxine dosage of 50-75 µg/day
 For elderly or if known ischemic heart disease
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Start at 1/4th to ½ of the expected dosage
Adjust in small increments after no less than 4-6 weeks
 Clinical benefits begin in 3-5 days and level off after 4-
6 weeks
 After dosage stabilization, monitored q 6 months or
annually
Hypothyroidism: Treatment
 If central (ie, pituitary or hypothalamic)
hypothyroidism
 Use T4 levels, not TSH levels to guide treatment
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In most cases, the free T4 level should be kept in the upper
third of the reference range
Hypothyroidism: Treatment
 Monitor the patients clinical status
 Look for evidence of overtreatment
 If symptoms continue after normalization of TSH
 Investigate other possible causes
Sub-clinical Hypothyroidism
 Controversy re treatment
 Treatment has been shown to reduce total cholesterol,
non-HDL cholesterol, to decrease arterial stiffness and
systolic blood pressure.
 In patients with concomitant subclinical
hypothyroidism and iron deficiency anemia, iron
supplementation may be ineffective if levothyroxine not
given
Sub-clinical Hypothyroidism
 Treat for TSH > 10 mIU/L
 Treat for TSH 5-10 mIU/L in conjunction with goiter
or positive anti-TPO antibodies (Guidelines from the
American Association of Clinical Endocrinologists)
References
 Garber, J., Cobin, R., Gharib, H., Hennessey, J., Klein, I., et al. (2012). Clinical practice
guidelines for hypothyroidism in adults: Cosponsored by the American Association of
Endocrinologist and the American Thyroid Association. Endocrine Practice, 18, 6, 9881028, Available at: https://www.aace.com/files/final-file-hypo-guidelines.pdf