Week 5- Hypothyroid Flashcards
1
Q
what is hypothyroid
A
inadequate production of T4 T3 by thyroid gland
OR
insufficient stimulation by hypothalamus (TRH) or pituitary gland (TSH)
2
Q
iatrogenic hypothryoid
A
from medical exam or treatment
3
Q
primary vs secondary vs tertiary hypothyroid
A
primary @ thyroid (t4 t3)
secondary (AKA central) @ pituitary (TSH)
territory (AKA central) @ hypothalamus (TRH)
4
Q
what type of hypothyroid (1,2,3) is most common
A
primary (95% of cases) are at the thyroid gland level
5
Q
ethology of primary hypothyroidism’s (5)
A
- iodine deficiency
- autoimmunity
- transient
- congenital abnoramilties
- infiltrative thyroid disease (rare)
6
Q
what is most common cause of hypothyroid in North America
A
autoimmune
7
Q
2 types of autoimmune hypothryoid? which is common?
A
- chronic autoimmune thyroiditis (Hashimoto thyroiditis) - most common
- subacute granulomatous thyroiditis (de Quervain disease) - rare
8
Q
what is transient causes of primary hypothryoid?
A
postpartum thyroiditis, pregnancy, silent thyroiditis, subacute thyroiditis, thyroiditis associated with TSH receptor-blocking antibodies
9
Q
what congenital abnormalities can cause primary hypothryoid?
A
aplasia/agenesis of thyroid, dyshormonogenesis
10
Q
what is infiltrative thyroid diseases that can cause primary hypothryoid
A
(rare): amyloid goiter, black thyroid, cystinosis, diffuse lipomatosis, hereditary hemochromatosis, langerhans cell histiocytosis, reidel’s thyroiditis, sarcoidosis, scleroderma
11
Q
what is the most common cause of central (secondary and tertiary) hypothyroid
A
pituitary adenomas
12
Q
etiology of central (secondary + tertiary) hypothyroidism (7)
A
- pituitary tumors
-sheehan syndrome
-lymphocytic hypophysitis
– brain tumors compressing hypothalamus
- thyroid releasing hormone (TRH) resistance
- TRH deficiency
- radiation therapy to the brain
13
Q
what is Sheehan syndrome
((etiology of central (secondary + tertiary) hypothyroidism))
A
a rare condition involving injury to your pituitary gland
following extreme blood loss during childbirth
14
Q
what is lymphocytic hypophysitis
((etiology of central (secondary + tertiary) hypothyroidism))
A
a rare, autoimmune condition of the pituitary gland
15
Q
iatrogenic hypothryoid
A
MEDICATIONS
- amiodarone
- antibiotics: rifampin, ethionamide
- anti-convuslants: phenytoin, carbamazepine
- anti-neoplastics: tyrosine kinase inhibitors
(sunitinib, imatinib), bexarotene, interleukin-2,
- dopamine - opioids
- prednisone
procedures
anti-CTLA-4 and anti-PD-L1/PD-1
- interferon-α -
- lithium
- perchlorate -
- phenobarbital
- stavudine
- thalidomide
PROCEDURES
-radiotherapy to head or neck area
-thyroid radioactive iodine -therapy thyroid surgery
16
Q
effects of thyroid hormones on the body (and therefore hypothyroid is opposite)
A
increase metabolism
increase body heat
increase GI motility
neuronal development
SNS (fight or flight)- increase HR, RR, mental alertness
17
Q
impacts of low thyroid hormones on body functions
A
- skin: reduced sweating, skin discoloration, coarse hair (or loss), brittle nails, non-pitting edema, periorbital edema
- hematologic: hypocoagulability (bleeding risk), pernicious anemia
- cardiovascular: bradycardia, pericardial effusion, diastolic hypertension
- respiratory: shortness of breath on exertion, rhinitis, decreased exercise capacity
- gastrointestinal: constipation, decreased taste, nonalcoholic fatty liver disease
- reproductive: menstrual irregularities, decreased libido, infertility, miscarriage,
erectile dysfunction, delayed ejaculation, reduced sperm morphology - neurologic: hashimoto encephalopathy, myxedema coma
- muscular: weakness, cramps, myalgias (high serum creatine kinase)
- mental: depression, anxiety, poor concentration, decreased short-term memory
- metabolic: hyponatremia, hyperlipidemia, hypercholesterolemia, hyper-
homocysteinemia, hyperuricemia, reduced drug clearance (e.g. hypnotic, opioid) - weight gain
18
Q
what does hypothyroid do to cause symptoms (2 main effects)
A
generalized slow metabolism or accumulation of polysaccharides in interstitial spaces
generalized slow metabolism causes constipation, weight gain, fatigue, brittle nails, bradycardia, slow speeach
the accumulation of polysaccharides causes things to do with water retention and swelling (puffy face, pleural effusion, pericardial effusion, weight gain)
19
Q
common symptoms of hypothyroid
A
- weight gain
- fatigue, lethargy, depression
- weakness, dyspnea on exertion, arthralgias or myalgias, muscle cramps
- menorrhagia
- constipation
- dry skin, hair changes (dryness, thinning, loss)
- headache, paresthesias, carpal tunnel syndrome, raynaud syndrome
- cold intolerance
- voice changes
20
Q
common clinical findings in hypothyroid
A
- bradycardia
- diastolic hypertension
- thin, brittle nails
- thinning hair or alopecia (including lateral 1⁄3 of eyebrow thinning)
- peripheral edema
- puffy face and eyelids
- skin pallor or yellowing (carotenemia)
- delayed relaxation of deep tendon reflexes
- goiter (chronic autoimmune hypothyroidism: firm, then shrinks with fibrosis)
21
Q
what is a goiter
A
- enlargement of the thyroid gland, can be diffuse, nodular or multinodular
22
Q
what is an endemic goiter from
A
iodine deficiency
23
Q
physiologic goiter
A
adolescence and pregnancy
24
Q
when can a goiter be a symptoms of hyperthyroidism
A
Grave disease, toxic nodular/multinodular goiter thyroid cancer or infiltrative disease (e.g. sarcoidosis)
25
when a goiter can be a symptom of inflammatory disorders (thyroiditis)
autoimmune, postpartum,
silent, radiation, subacute, suppurative
26
what type of thyroid condition are gaiters most common in
can be euthyroid, hypothyroid or hyperthyroid - most goiters are euthyroid
27
management for goiter
referral for ultrasound, fine-needle aspiration biopsy (if nodule), treatment varies with serum findings
28
symptoms for autoimmune hypothryoid
none alone have a high LR+ when combine multiple symtpoms get a better picture
29
what is euthyroid sick syndrome
often seen in hospitalized settings (patients with severe critical illness, deprivation of calories, and following major surgeries)
30
what is ridel thyroiditis
a rare inflammatory disease of the thyroid, causing compression and fibrosis of the thyroid and adjacent tissues
31
what is subacute thyroiditis
an immune reaction of the thyroid gland that often follows an upper respiratory infection
32
what is thyroid lymphoma
a rare thyroid malignancy where lymphoid cancer cells cause the thyroid gland to rapidly enlarge
33
if TSH is normal but symptoms persists; what things may co-exist with hypothryoid too
anemia (vitamin B12 or iron deficiency) autoimmune (rare)
- adrenal insufficiency (aka. Addison’s disease)
- atrophic gastritis with pernicious anemia
- celiac disease or gluten sensitivity
- diabetes mellitus type 1
- rheumatoid arthritis chronic kidney disease liver disease menopause
mental health disorder (i.e. depression, anxiety or somatoform disorder) obstructive sleep apnea
viral infection (e.g. mononucleosis, lyme disease, HIV)
34
things that can causes aberrations in lab tests: high TSH
Acute psychiatric illness (transient,14%) Anti-mouse antibodies
Antithyrotropin antibodies
Anti-TSH receptor antibodies Autoimmune disease (assay interference)
Drugs Amiodarone
Amphetamines Atypical antipsychotics Dopamine agonists Heroin Phenothiazines Exercise before testing
Following prolonged primary hypo- thyroidism
Heterophile antibodies
Laboratory error
Macro-thyrotropin
Nonadherence to thyroid replacement therapy
Older adults (especially women) Pituitary TSH hypersecretion Recovery from acute nonthyroidal illness (transient)
Strenuous exercise (acute)
Sleep deprivation (acute)
TSH resistance
35
what factors may cause aberrations in lab tests: low t4 and t3
Acute psychiatric illness Cirrhosis
Familial thyroid-binding globulin deficiency
Laboratory error Nephrotic syndrome Severe illness Drugs
Androgens
Antiseizure drugs (Carbamazepine, Phenobarbital, Phenytoin)
Asparaginase Carbamazepine (T4) Chloral hydrate Corticosteroids
Diclofenac (T3), naproxen (T3) Didanosine
Fenclofenac
5-Fluorouracil
Halofenate
Imatinib
Mitotane
Nicotinic acid
Oxcarbazepine
Phenobarbital
Phenytoin
Salicylates, large doses (T3 + T4) Sertraline
Stavudine T3 therapy (T4)
36
what 2 natural health products to be aware of affecting thyroid levels in labs
1. biotin
2. st johns wort
37
what does biotin do to thyroid levels
falsely high fT4 and fTA3
falsely low TSH
38
does biotin affect thyroid function
no- but looks like it on labs
does not impair thyroid function but can interfere with laboratory testing
falsely high fT4 and fT3
falsely low TSH
- appears as hyperthyroidism or thyroid replacement dosing is too high
- avoid interference by having patients discontinue biotin at least 48hr prior to
testing
39
what does st johns warts do to thyroid
transiently elevated TSH levels (no effect on fT4)
40
TSH and fT4 is primary vs central (secondary or tertiary) hypothryoid
central= low TSH, low fT4
primary= high TSH, low fT4
41
what is central hypothyroid
hypothyroidism due to insufficient stimulation by thyroid stimulating hormone (TSH) of an otherwise normal thyroid gland; can be secondary (pituitary) or tertiary (hypothalamus) in origin
42
how common is central hypothyroid
< 1% of hypothyroid cases
43
what could cause central hypothyroid in children
craniopharyngiomas, hx of cranial irradiation (brain or hematological cancer)
44
what could cause central hypothyroid in adults
pituitary macroadenomas, pituitary surgeries or post-irradiation
transient: sick euthyroid syndrome, over-replacement of T4 (primary hypothyroidism)
45
what are the symptoms ofd central hypothyroidism
hypothryoid symptoms but milder
46
diagnosis of central hypothryoid via blood markers
- low serum fT4, relatively low serum TSH
47
management of central hypothyroidism
referral - TRH Stimulation Test
48
what is subclinical hypothyroidism
endocrine disorder presenting with elevated TSH but normal thyroxine (fT4)
49
symptoms of subclinical hypothyroid
asymptomatic (most often) or hypothyroid symptoms
50
diagnosis of subclinical hypothyroid (blood markers)
- elevated TSH > 4.0 mIU/L; fT4 within range
serum TSH and fT4 +/- symptoms +/- TPO antibodies
51
when would you treat vs when would you not treat subclinical hypothryoid
treat: TSH >10, TPO antibodies present, patient symptomatic or has CVD risk factors (i.e. high cholesterol)
dont treat: if TSH between 4-10mIU/L
treatment recommended if TSH >10 mIU/L, TPO antibodies present, patient is symptomatic or has cardiovascular risk factors (e.g. ↑ cholesterol)
if TSH is 4.0 - 10.0 mIU/L, monitor TSH q6-12mo
52
prognosis of subclinical hypothyroid
60% resolve without intervention within 5yrs, 2-6% develop overt thyroid dysfunction (if anti-TPO present, risk is up to 50% over 20 yrs)
- increased risk of fracture, ischemic heart disease and heart failure if TSH > 10 mIU/L
53
primary hypothryoid
endocrine disorder presenting with elevated serum TSH and low thyroxine (fT4)
54
what other diseases does primary hypothryoid usually present with
autoimmune disease (e.g. T1DM, celiac disease), Down or Turner syndrome
55
what is the diagnosis for primary hypothryoid via blood
high TSH, low fT4
- high thyrotropin (TSH) > 4.0 mIU/L, low thyroxine (fT4) < 12 pmol/L
- thyroid peroxidase antibody (anti-TPO) testing does not help diagnosis, but
indicates autoimmune etiology
56
how to manage primary hypothyroid
thyroid hormone replacement therapy (T4)
57
CTFPHC screening recommednations
dont screen in asymptomatic and non pregnant
- The Canadian Task Force on Preventive Health Care (CTFPHC) strongly recommends against screening for thyroid dysfunction in asymptomatic, nonpregnant adults
- not likely to confer clinical benefit, but could lead to unnecessary treatment for some patients and consume resources
- treating asymptomatic adults for screen-detected hypothyroidism may result in little to no difference in clinical outcomes
58
current evidence for screening
The US Preventive Services Task Force (USPSTF) states that current evidence is insufficient to assess the balance of benefits and harms of screening for thyroid dysfunction in nonpregnant, asymptomatic adults
59
management for primary vs subclinical vs secondary hypothryoid
primary: Levothyroxine
(T4 replacement therapy)
subclinical: if TSH > 10 mIU/L + positive thyroid antibodies, cardiovascular risk, or treatment-resistant depression then consider Levothyroxine
(T4 replacement therapy)
secondary: brain MRI (for tumor)
60
what happens to thyroid hormone in pregnancy
20% to 40% increase in thyroid hormone requirement as early as 4 weeks
61
what does estrogen do to thyroid hormones
estrogen-mediated increase in thyroid-binding globulin, increased volume of
distribution of thyroid hormone, as well as the placental metabolism and
transport of maternal thyroxine
also thyroid gland size icnrease
62
what trimesters levels for TSH, fT4, fT3 (chart of slide 36)
TSH increases over the trimesters
ft4 and ft3 decrease slightly
63
what happens to thyroid antibodies in pregnancy
thyroid antibodies decrease drastically later in pregnancy; so dont test for autoimmune thyroid then bc worst be accurate
64
what's the hypothryoid that would happen in prgnengcy
chronic autoimmune hypothryoid
around 1%
65
what are the effects of having hypothryoid in pregnancy
- miscarriage
- gestational hypertension
- pre-eclampsia
- anemia
- postpartum hemorrhage
- abruptio placentae
- preterm birth + low birth weight - fetal neurocognitive deficits
66
what can thyroid hormone replacement therapy do in perngnacy
(levothyroxine, LT4):
- little to no effect on hypertensive disorders and placental abruption
- reduces miscarriage, preterm birth
- improves fetal intellectual development
67
what has the highest odds ratio in hypothyroid related complications in pregnancy
post partum thryioditis risk
68
if known to have hypothryoid before prenancy what should u do to medication dose
increase
increase thyroxine by 30% once pregnancy is confirmed unless preconception TSH <1.5 mIU/L
69
postpartum thryoidistis
abnormal TSH level within the first 12 months postpartum in the absence of a toxic thyroid nodule or thyrotoxin receptor antibodies
increased risk of permanent hypothyroidism
70
what increases risk of postpartum thyroiditis
risk increased in T1DM and those with thyroglobulin (TG) or thyroperoxidase (TPO) autoantibodies
71
postpartum thyroiditis symptoms
can mimic the fatigue typically following delivery or postpartum depression
43% present with symptoms of hypothyroidism; 32% present with symptoms of hyperthyroidism; 25% of patients present with symptoms of hyperthyroidism followed by hypothyroidism and then recovery
72
postpartum thyoiditis' hyper vs hypo labs
- hyperthyroid state: low serum TSH, high-normal fT4 and fT3
- hypothyroid state: high serum TSH, low-normal fT4
73
hypothyroidism and relative risk of other autoimmune diseases; what does it increase the most with
Addisons disease
74
hypothyroid and celiac disease ; what needs to happen to medications for thyroid ? what can alter these changes?
increase meds, but maybe not if go gluten free
increased therapeutic dose (nearly 50% more) needed for patients with hypothyroidism and celiac disease
- dose often can be reduced by following a gluten-free diet
- gluten-free diet doesn’t significantly affect thyroid antibody levels
75
Addison disease/ adrenal insufficiency
an acquired primary adrenal insufficiency due to autoantibodies causing destruction of adrenal cortical tissue; rare, but potentially life-threatening emergency
76
symptoms of Addison disease
fatigue, generalized weakness, weight loss, nausea, vomiting, abdominal pain, dizziness, tachycardia, and/or postural hypotension; hyperpigmentation
77
what do you need to diagnose addisons
low cortisol high ACTH
low Na, high K
- morning cortisol (<140nmol/L) combined with ACTH (2x upper limit)
- low Na+, high K+ and hypotension
78
what to treat addison
referral for ACTH stimulation for confirmation and comanagement
79
prognosis of addison
up to 50% of patients may develop another autoimmune disease adrenal crisis if not treated (hypoglycemia, hypotension, shock, death)
80
hypothyroid and Addison
thyroid hormone replacement may precipitate an adrenal crisis in unrecognized patients:
- pain in back, abdomen or legs
- vomiting + diarrhea leading to dehydration and low blood pressure
- progresses to loss of consciousness and death
81
what has good LR- in Addison/ primary adrenal insufficiency
AM cortisol >380
serum basal cortisol >350
therefore if dont see these things than rule out lol idk
82
what is the order of treatment for hypothyroid and Addison/adrenal
1st Addison than hypo
- in patients with suspected or known adrenal insufficiency, testing and treatment for adrenal insufficiency should be done first
- adrenal insufficiency can be associated with subclinical hypothyroidism that is reversible with treatment of adrenal insufficiency
- in confirmed adrenal insufficiency, thyroid tests should be reassessed following adequate treatment of adrenal insufficiency
83
what heart thing does hypothryoid increase
increased risk of coronary artery disease in overt hypothyroidism
84
what does hypothryoid effect on the heart
- reduces cardiac output, cardiac contractility and heart rate
- increases peripheral vascular resistance
- increases atherosclerotic risk factors, most notably:
- hypercholesterolemia
- diastolic hypertension
85
what effect can thyroid replacement therapy have on the heart
((precipitate acute coronary syndrome or an arrhythmia))
thyroid replacement therapy increases heart rate + contractility (therefore myocardial oxygen demand), and can precipitate acute coronary syndrome or an arrhythmia - start with low dosing thyroid replacement and proceed slowly
86
what happens with hypothyroidism and age? what to do with meds?
- TSH increases with age, but fT4 does not
- thyroid replacement therapy started at lower doses than in younger patients
87
reasons why a stable TSH may become abnormal
- change in adherence (e.g. missing a dose) or timing relative to eating
- malabsorption (e.g. celiac disease, helicobacter pylori gastritis)
- pregnancy
- initiation of new medication:
- androgens or estrogens
- heroin / methadone
- medications that decrease absorption (see next slide)
- medications that reduce levothyroxine conversion to T3 (amiodarone,
high-dose beta-adrenergic agonists, glucocorticoids)
- medications that may reduce serum protein binding of levothyroxine
(carbamazepine, phenytoin)
- SSRI or tricyclic antidepressants
- tamoxifen
88
what medication can reduce levothyroxine absorption and should therefore be taken 4 hours before or after
- bile acid sequestrants (e.g. colesevelam, cholestyramine, colestipol)
- calcium carbonate
- ferrous sulfate
- intragastric pH elevation via hypochlorhydria
- antacids (e.g. aluminum, magnesium)
- proton pump inhibitors - simethicone
- sucralfate
- ion exchange resins (e.g. sodium polystyrene sulfate, sevelamer)
- orlistat
89
how does levothyroxine effect diabetes medication
may increase dosing of diabetes medications to achieve glycemic control
90
levothyroxine and food interactions
patients who regularly consume walnuts, dietary fibre, soybean flour, cottonseed meal or grapefruit juice may need higher doses of levothyroxine
91
ketamine therapy and levothyroxine interactions
concurrent use may result in significant hypertension and tachycardia
92
oral anticoagulants and levothyroxine
may increase effects
93
SSRIs and TCAs interact with levothyroxine
may increase therapeutic and toxic effects
94
sympathomimetic and levothyroxine
concurrent use may increase risk of cardiac event in patients with coronary artery disease
95
complication of hypothyroid if left untreated, patient at risk of:
- cognitive impairment
- susceptibility to bacterial pneumonia
- developing megacolon
- developing cardiovascular disease (including heart failure)
- rhabdomyolysis (may lead to kidney dysfunction)
- infertility and miscarriage
- myxedema
- mortality
96
what is a myxoedema coma
rare, severe, life-threatening manifestations of hypothyroidism
97
who and when is myedema coma most likely in
female, > 60 yrs, winter
inadequate/interrupted treatment, undiagnosed hypothyroidism, or presence of acute illness (e.g. sepsis, stroke, heart failure, infection (e.g. pneumonia), trauma), medications (sedatives, antidepressants, hypnotics, anesthetics, opioids, etc)
98
what are symptoms of myxoedema coma
altered mental status (lethargy, impaired cognition, confusion, coma), seizure(s), abdominal pain, N/V, respiratory failure, fluid/urine retention (incl. ascites)
99
what clinical manifestations that are of myxoedema coma
- hypothermia (<35.5°C), hypotension, bradycardia, hypoventilation
- non-pitting edema, hyponatremia, hypoglycemia, arrhythmia(s), dry skin
100
management for myxedema coma
911 emergency
101
when to refer to an endocrinologist for hypothyroid
- age 18 yrs or younger
- elusive euthyroid state
- myxedema, suspected
- pregnancy
- simultaneous presence of another endocrinopathy
- structural changes in thyroid gland (e.g. goiter, nodule)
- symptoms do not improve or worsen after treatment with levothyroxine (T4)
- unstable ischemic heart disease
102
hypothyroid symptoms from
generalized slow metabolism or accumulation of polysaccharides in interstitial spaces
weight gain
fatigue
sensitive to cold
constripation
dry skin
puffy face
hoarse voice
muscle weakness
thin hair
slow HR
depsesssion
impaired memroy
enlarged goiuter
irregular periods
103
PAGE 59 CHART
REALLY GOOD FOR DIFFERENTIATION THE HYPOTHYROID TYPES
104
when to test antibodies for hypothyoid
antibodies aren’t routinely tested since majority of cases are autoimmune
105
subclinical hypo treat
- subclinical hypothyroidism often resolves on its own, but treatment may reduce risk of fracture, ischemic heart disease and heart failure if TSH > 10mIU/L
