Thyroid Flashcards
The Hypothalamus secretes:
TRH
The Anterior Pituitary Secretes
TSH
Thyoid Gland Secretes
T3/T4
T3 is more
Metabolically active; In liver and gut microbiome
T4 is more
Abundant (85%)
Primary issues of the thyroid indicate issues at:
Thyroid gland
Secondary issues of the thyroid occur at:
Anterior pituitary
Tertiary issues of the thyroid occur at:
Hypothalamus
Primary carrier of T3/T4
Thyroid Binding Globulin
-85% of T4
-70% of T3
Hyperthyroidism: Signs/Symptoms
-Exopthalamos
-Lid lag
-Increased HR
-Warm skin
-Weight loss
-Missed/infrequent periods
-Fatigue: Lack of sleep
Hypothyroidism: Signs/Symptoms
-Loss of hair in outer 1/3 of eyebrows
-Cold, dry skin
-Cold intolerance
-Weight gain
-Heavy menses: First sign
-Fatigue
Thyroxine, Total T4
-Total amount of T4: T4 bound to TBG & free T4
-Interference: Altered levels of TBG
Thyroxine (Total T4): Newborn*
<7ug/dL: Congenital Hypothyroidism
Thyroxine (Total T4): Adult
<2ug/dL: Myxedema coma possible
>20ug/dL: Thyroid storm possible
Thyroxine: increased Levels
-Hyperthyroid States:
-Acute Thyroidism
-Pregnancy
Thyroxine Decreased Levels
Hypothyroid States
Free Thyroxine Assay (free T4)
One of the best tests of thyroid function
T3U Test
-Capacity of TBG to bind labeled T3 at unsaturated T4 sites on TBG
T3U: Hyperthyroidism
-Less open seats
-More T3 at resin column
-Increase in T3 uptake
Increased TBG Causes
-Pregnancy
-Oral Contraceptives (or estrogen therapy)
-Certain liver conditions
-Less T3U at resin column
T3U: Decreased TBG Causes
Testosterone Treatment
More T3U at resin column
Free Thyroxine Index
Corrects TBG alterations
FTI= T4 X T3U
Triiodothyronine Tests (T3 by RIA) are used to detect
T3 thyrotoxicosis
-Not accurate for hypothyroidism
Reflexes
-Hypothyroidism: Decreased reflexes
-Hyperthyroidism: Increased reflexes
Cholesterol
-Myxedema: Elevated TC (decreased thyroid hormone)
-Hyperthyroidism: low TC (increased thyroid hormone)
TSH is important in differentiating:
Primary and secondary hypothyroidism
Primary vs. Secondary hypothyroidism
-Primary: Increased TSH
-Secondary: Decreased TSH & T3/T4
TSH: Increased TSH
Primary Hypothyroidism
Decreased TSH
Secondary Hypothyroidism
TRH Assay
Important in differentiating secondary or tertiary hypothyroidism
Secondary vs. Tertiary Hypothyroidism
-Secondary: Injected TRH/Low TSH (Anterior Pituitary Issue)
-Tertiary: Inject TRH/High TSH (Hypothalamus Issue)
Thyroid Antibodies are most important in determining
Hashimoto’s Thyroditis
Thyroid Antibodies
-Anti-TPO* BEST
-Antithyrogloblin Test
Thyroid Screening begins at what age?
-Begins at 35 (Every 5 years)
Suspected Hypothyroidism: Needed tests for diagnosis
TSH, Free T4, anti-TPO at minimum
Hypothyroid Conditions
-Primary Hypothyroidism: Most Common
-Post-therapeutic Hypothyroidism: 2nd MC
-Goitrous Hypothyroidism: Pregnancy, Menopause..
-Secondary Hypothyroidism: Can’t Secrete TSH
Primary Hypothyroidism is typically due to:
An autoimmune disease usually as sequela of Hashimoto’s thyroiditis
Post-Therapeutic Hypothyroidism is due to:
• Radioactive iodine treatment or surgery for hyperthyroidism
Causes of Goitrous Hypothyroidism
- Pregnancy, Menopause, Iodine Deficiency Hashimotos
Secondary Hypothyroidism is the failure of:
Anterior Pituitary (Can’t secrete TSH)
Tertiary Hypothyroidism is due to a failure of:
Hypothalamus (Decrease in TRH)
Congenital Hypothyroidism: Key Signs/Symptoms
• Drooling
• Broad face
• Umbilical hernia, out belly
Hypothyroidism: Most Common Symptoms
MC Symptoms (can have 1+ but varies): Weakness/fatigue/lethargy, decreased memory, modest weight gain (10 lbs), coarsening/huskiness of voice, menstrual changes (typically first sign), sensitivity to cold
Hypothyroidism: Key Neurological Complications
Neurological Complications: Headaches, bilateral carpal tunnel, symmetrical/primarily sensory peripheral neuropathy
Hypothyroidism: Musculoskeletal Complaints
Musculoskeletal: Myalgia (morning stiffness; Affects hips/thighs & shoulders), Arthralgia (spine, hands, knees, hips), muscle spasms
Hypothyroidism: Mental Symptoms
Mental: Mental apathy, Drowsiness, Personality changes
Myxedema Coma
Myxedema Coma (more serious): Long-standing hypothyroidism, coma with severe hypothermia, areflexia/seizures/respiratory depression
Myxadematous Facies
• Large tongue
• Slow, deep-toned speech
• Dry, thick skin
• Puffy hands and face
• Dull facial expression, eyelids droo
Congenital Hypothyroidism: Labs
• Increased serum TSH
•T3/ T4 decreased
• ALP decreased
• Cholesterol increased
Primary Hypothyroidism: Labs
-Primary Hypothyroidism: T4 decreased T3U decreased, TSH increased
Primary Hypothyroidism: Thyroid Labs
-Thyroid: T4 decreased T3U decreased, TSH increased
Secondary Hypothyroidism: Labs
-Secondary Hypothyroidism: T4 decreased, T3U decreased, TSH decreased*
Hypothyroidism: Cholesterol/Anemia/Enzyme Labs
-Cholesterol: Increased
-Anemia: Any morphological type
-Other: ALP decreased, increased CPK (d/t muscle atrophy, increased AST
Hyperthyroidism: Etiologies
- Toxic diffuse goiter: Autoimmune (Grave’s Disease)
- Toxic nodular goiter: Plummer’s Disease
- Thyroiditis Factitial: “Fake”
- Thyroiditis forms
- Secondary Hyperthyroidism: Space Occupying Lesion
- T3 Thyrotoxicosis
- Thyroid Storm: Emergency
Hyperthyroidism: Main Signs/Symptoms
• Nervousness (85%)
• Increased sweating (70%)
• Hypersensitivity to heat (70%)
• Dyspnea (75%)
• Fatigue and weakness (60%)
• Increased appetite (40%)
• Weight loss (50%)
Grave’s Disease: Eye Signs
• Lid lag
• Stare
• Exophthalmos
• Increased lacrimation
• Orbital pain
• Ocular muscle weakness
Grave’s Disease: Thyroid Dermopathy
• Thyroid dermopathy – lesions of skin due to deposition of hyaluronic acid
Primary Hyperthyroidism: Thyroid Labs
• T4: Increased
• T3U: Increased
• TSH: Decreased
Primary Hyperthyroidism: Cholesterol
Decreased
Hyperglycemia can occur in:
BOTH hyper and hypothyroidism
Primary Hyperthyroidism: Antibodies
-Anti-Body Tests: + Thyroid-Stimulating Immunoglobulin (TSIs)**, + TSH receptor antibodies;
-Possible: + TPO, + thyroantibodies
Hypothyroidism: Management
Management: Thyroid Hormone for Life
-Referral to endocrinologist
Hyperthyroidism: Management
• Iodine in pharmacologic doses
• Antithyroid drugs
• Radioiodine therapy
• Surgery
-Referral to Endocrinologist
Euthyroid Goiter
• Enlarged thyroid gland w/o clinical or lab evidence of thyroid dysfunction
-MC during: Pregnancy, Menopause, Puberty
Euthyroid goiter: Signs & Symptoms
• Soft, symmetric, smooth goiter
• History of iodine intake or ingestion of goitrogen
Euthyroid Goiter: Thyoid Labs
• T4 and T3U normal
• TSH increased
• Thyroid antibodies should be ordered to rule out Hashimoto’s thyroiditis
Thyroiditis
• A variety of inflammatory thyroid disorders that can cause thyroid enlargement and atrophy
• May lead to hypothyroidism or hyperthyroidism
Subacute Granulomatous Thyroiditis: Signs/Symptoms
• Pain in neck: Radiates to jaws, arms, or chest
• Aggravated by swallowing or turning head
• Low grade fever
• Lassitude, malaise, prostration
-Recent Viral Infection
Subacute Granulomatous Thyroiditis: Signs/Symptoms
• Pain in neck: Radiates to jaws, arms, or chest
• Aggravated by swallowing or turning head
• Low grade fever
• Lassitude, malaise, prostration
-Recent Viral Infection
Subacute Granulomatous Thyroiditis: Progression
• Hyperthyroidism, phase of mild hypothyroidism, resolution
Subacute Granulomatous Thyroiditis: Expected Labs
• ESR, CRP elevated
• T4 increased
• WBC normal or decreased (viral)
• Anti-thyroglobulin antibodies may be present
Hashimoto’s Thyroiditis: Signs/Symptoms
• Fullness in throat
• Gland is painless, firm
___% of Hashimoto’s will end up with hypothyroid
90%
Hashimoto’s Thyoiditis: Early Stages
-Early Stages: T4/TSH normal & high levels of TPO antibodies
Hashimoto’s Thyroidism: Thyroid/Cholesterol Labs
(If Hypothyroid)
decreased T3 &T4 /increased TSH
-Cholesterol: Elevated
Hashitmoto’s Thyroiditis: Antibodies
Anti-TPO antibodies*, anti-thyroglobulins
Hashimoto’s Thyroiditis: IF hyperthyroidism
If hyper: Hashitoxicosis (Low TSH/High T3/T4)
Most common form of thyroiditis
Hashimoto’s
Hashimoto’s Thyroiditis often presents as:
Asymptomatic diffuse goiter
Hashimoto’s is most prevalent in: Gender/Age
-Women
-30-50 years of age
“Silent” Lymphocytic Thyroiditis
• Spontaneously resolving hypothyroidism and/or hyperthyroidism associated with pregnancy
• Occurs in about 5-10% of postpartum women
Thyoid Neoplasm (Cancer): Signs/Symptoms
• Mass in neck (painless)
• Pain and tenderness are infrequent
• Hard, irregular, fixation of gland to adjacent structures
• Symptoms due to metastasis
-Hoarseness, voice change
Thyroid Neoplasm: Lab Findings
• Thyroid function tests usually normal
• Hormone levels normal
• Fine Needle Aspiration (FNA)
• Thyroid scan, sonogram
Thyroid Neoplasm: Treatment
• Surgery
• Hormone for life
Subclinical Hyperthyroidism: Symptoms
• Asymptomatic or minimal symptoms of hyperthyroidism
Subclinical Hyperthyroidism: Labs
Low TSH, normal free T4 and T3 levels
-Hyperglycemia
SC Hyperthyroidism is _____ common than SC hypothyroidism
Less
SC Hyperthyroidism: Most Common Cause
Administration of thyroid hormone
SC Hyperthyroidism: Other Causes
Other causes – developing Grave’s disease, autonomous thyroid nodules
SC Hypothyroidism: Symptoms
• No or minimal symptoms suggestive of hypothyroidism
SC Hypothyroidism: Labs
• High TSH, normal free T4 and T3 levels
-Hyperglycem
______ should be measured in all cases of subclinical hypothyroidism
TPO antibodies
SC Hypothyroidism: Screening
-Hypercholesterolemia
-TPO antibodies
-TSH
-Thyroid Hormones
