Thyroid Disorders Flashcards
Hypothyroidism and Hyperthyroidism thyroid hormone levels?
TSH
T4
T3
Hypothyroidism
TSH- high
T4- Low
T3- low
Hyperthyroidism
TSH-low
T4- high
T3- low
What is a goiter?
Whats the most common cause of goiters and what is the mechanism?
Abnormal growth of the thyroid gland
Iodine deficiency most common cause world wide—mechanism?
Iodine rich foods…..sea vegetables, yogurt, cheese, navy beans, strawberries, potatoes, shellfish, eggs, shrimp, sardines
What are the most common causes in the US?
3
- Multinodular goiter (most common in elderly)
- Chronic autoimmune (Hashimoto’s) thyroiditis
- Grave’s disease
Goiter Obstructive Symptoms
3
- Monotone voice
- Dysphagia (difficulty swallowing)
- Tracheal compression
Test for Diagnosis for goiter?
if this test is high what should we measure?
Most common cause?
If this test is low what should we do? 3
What is the most common disease?
Obtain TSH:
If high—measure serum free T4—Diagnosis?
Most common cause is Hashimoto’s thyroiditis
- If low—measure free T4, serum total T3—Diagnosis?
- Consider Ultrasound
- Need 24-hour radioiodine uptake scan
Multinodular goiter/Grave’s disease most common
Most common cause of hypothyroidism?
There are three types. What are they?
Most common cause is Hashimoto’s Thyroiditis
Three types – Primary, Secondary and Tertiary
Primary Hypothyroidism causes?
7
- Iodine deficiency
- Autoimmune: Hashimoto’s
- Iatrogenic: Iodine-131 therapy, thyroidectomy
- Post Partum Thyroiditis
- Drug induced: Lithium, Amiodarone, antithyroid drugs
- Congenital: agenesis, dysgenesis, hypoplastic
- Adult onset: normal aging
Secondary Hypothyroidism causes?
5
- Neoplasm
- Surgery
- Post partum necrosis
- Cushing’s
- Radiation
Tertiary Hypothyroidism causes?
3
- Hypothalamus dysfunction
- Hemochromatosis
- Sarcoidosis
Things you will find in the history for hypothyroidism?
10
- Fatigue
- Cold intolerance
- Weakness
- Lethargy
- Weight gain
- Constipation
- Myalgias
- Arthalgias
- Menstrual irregularities
- Hair loss
Physical findings for hypothyroidism?
7
- Dry, course skin
- Hoarse voice
- Brittle nails
- Periorbital, Peripheral edema (myxedema)
- Delayed reflexes
- Slow reaction time
- Bradycardia
Diagnosing Hypothyroidism
The thyroid-stimulating hormone (TSH) level is elevated. What does this indicate?
2
- indicating that thyroid hormone production is insufficient to meet metabolic demands
- free thyroid hormone levels are depressed
Can have “sub-clinical hypothyroidism.” What will your lab levels look like?
3
T3, T4 are within normal limits but TSH mildly elevated
Hypothyroidism treatment?
Thyroid hormone: usually 100 to 200 mcg daily
Can start with 50-100mcg QD
Levothyroxine (T4) {Synthroid}
-monitor TSH for response
Hypothyroidism treatment in the elderly?
In the elderly, start with 25-50 mcg and increase by 25 mcg every 2-3 weeks
Levothyroxine (T4) {Synthroid}
-monitor TSH for response
Monitoring Thyroid Function:
Patients with an intact hypothalamic-pituitary axis how should we monitor?
How about patients with a pituitary insufficiency?
Follow with serial TSH measurements
Measurements of free T4 and T3
How often should we monitor hypothyroidism?
8-12 weeks
We should have stable dosing until the 7th decade. Why would we have to adjust it then?
With age, thyroid binding may decrease, and the serum albumin level may decline. In this setting, the Levothyroxine dosage may need to be reduced by up to 20 percent
Hypothyroidism
syndromes?
3
Hashimotos Thyroiditis
Myxedema
Subclinical Hypothyroidism
Whats the most common form of thyroiditis?
Whats another name for it?
What disease can it be associated with?
Hashimoto’s Thyroiditis
AKA chronic lymphocytic thyroiditis
It can be associated with non-Hodgkins lymphoma (NHL)
What kind of disorder is hashimoto’s?
When in life does it usually occur?
Where is this the most common cause of hypothyroidism?
Autoimmune disorder
Usually occurs between the third and sixth decade
Most common cause of hypothyroidism in areas where there is sufficient iodine
Hashimoto’s Thyroiditis
has what thyroid antigens that cause the autoimmune disease? 3
Precipitating factors for hashimoto disease? 4
- Thyroglobulen (Tg)
- Thyroid peroxidase (TPO)
- The thyrotropin (TSH) receptor
- Infection
- Stress
- Sex steroids, pregnancy
- Radiation exposure
Most common signs and symptoms of Hashimoto’s?
7
- Painless goiter
- Fatigue
- Muscle weakness
- Weight gain
- Feeling of fullness in the throat
- Neck pain, sore throat, or both
- Low-grade fever
Thyroid Scan-iodine marked with radioactive tracer. What does this test detect?
camera can detect how much of the tracer is taken up by the thyroid
Labs to do for Hashimotos?
4
Imaging to do for Hashimotos?
2
- TSH,
- Free T4
- TPOAb (anti-thyroid peroxidase antibody)
- TGAb (anti-thyroglobin antibodies)
- ultrasound to establish goiter size
- Radioiodine uptake
Treatment for Hashimoto’s?
What should we monitor?
Thyroid hormone replacement:
Levothyroxine (T4) (Levothyroid, Synthroid)
Monitoring of TSH is best and most reliable
Levothyroxine (T4) (Levothyroid, Synthroid) for patients with:
under 60 w/o CAD?
pregnant women?
over 60 or pts with CAD?
50-100mcg daily – under 60 w/o CAD
100-150mcg daily – pregnant women
12.5-50mcg daily – over 60 or pts with CAD
Mild thyroid failure is a common disorder that frequently progresses to overt hypothyroidism. What are strong predictors of this?
4
- Anti-TPO antibodies
- TSH >20
- Radioiodine ablation Hx (Grave’s Disease)
- Other radiation therapies
Populations at Risk for
Subclinical Hypothyroidism
5
- Women
- Prior history of Graves disease or postpartum thyroid dysfunction
- Elderly
- Other autoimmune disease
- Family history of
- Thyroid disease
- Pernicious anemia
- Type 1 Diabetes mellitus
Subclinical Hypothyroidism
Treatment and why?
In the absence of positive antibodies?
When should we consider treatment without positive antibodies?
2
Levothyroxine therapy is recommended in those patients with positive antibodies because they are at greatest risk to progress to overt hypothyroidism
Asymptomatic TSH less than 10mU/L - follow their TSH
TSH>10mU/L
TSH less than 10mU/L who are pregnant or have manifestations such as goiter, lipid abnormalities, anovulatory menses
Myxedema is thought to be related to what?
thought to be related to connective tissue proliferation in reaction to increased to TSH levels
The Myxedem patient will usually have a history of what?
WHo does it usually develop in?
Symtpoms? 4
hypothyroidism
Develops in older adults
- Droopy eyelids
- Lethargy, fatigue, mental sluggishness
- Decreased reflexes
- Mucopolysaccharide infiltration of the dermal space
Mucopolysaccharide infiltration of the dermal space in Myxedema causes what?
3
- Facial puffiness
- Periorbital edema
- Non-pitting pretibial edema
Treatment for Myxedema?
2
- Thyroid hormone replacement
Levothyroxine (T4) (Levothroid, Synthroid) - Monitor TSH