Lecture 10 - Thyroid Disorders Flashcards
T4 vs T3
T4»_space;» T3 secretion
T3»_space;> T4 activity
Hypothyroidism
Low T4/T3 and TRH/TSH high
Hyperthyroidism
High T4/T3 and TSH/TRH low
Hashimoto’s Disease
Autoimmune
auto-antibodies target thyroid peroxidsease, thyroglobulin, and other thyroid cell antigens
primary cause
Iatrogenic cause (caused by us)
usually secondary to management of hyperthyroidism
meds such as…lithium, amiodarone,etc
Secondary hypothyroidism
usually pituitary disease
Risk factors for Hypothyroidism
Female
Postpartum women
pts with head/neck thyroid irradiation or surgery
Primary pulmonary hypertension
Down’s/Turner’s syndrome
FH autoimmune thyroid disorders
Other Autoimmune disorders
Clinical presentation of Hypothyroidism
weak
slow reflexes
coarse skin and hair
cold or dry skin
bradycardia
slow speech, hoarse voice
Primary hypothyroidism TSH
> 4.5
Secondary hypothyroidism TSH
maybe within or below reference range
Treatment options hypothyroidism
T4 = Levo
T3 = liotrix
Combo = liothyronine
T4 (Levo) usually the answer
Levothyroxine info
Pro: Drug of choice, cheap, QD,stable
Cons: Drug/Food interaction impact absorption = empty stomach
* pick 1 manufacturer n stick with*
which thyroid product should be used for patients who want to avoid pork?
Thyroid USP = armor thyroid, nature-etc
more likely for SE
Liothyronine info
pro: rapid onset, uniform absorption
cons: TID, $$$, higher CV effects, hard to monitor
Starting dose Levothyroxine
normal: 1.6mcg/kg IBW
Hx CVD = 25mcg QD
Longstanding disease/elderly = 50mcg QD
adjusting dose levothyroxine
Titrate by 12.5-25 mcg/day if pts still hypothyroid
Long-term maintenance levothyroxine
Stick with 1 product manufacturer
Recheck in 3 months, then every 6-12 months
Special pop, recheck TSH 4-6wk after adjustment
Preg, inc req in 75% of women
Elderly, dec dose req
Weight loss, may need dec dose req
Goal TSH?
0.5-4.5 for exam purposes
Levothyroxine SE
Allergic reactions
reduced BMD and inc risk of fracture
excessive doses = HF, angina pectoris, MI
DDI Levothyroxine
stuff affecting stomach and GI absorption
give before food/meds
Levothyroxine CI
Hypersensitivity
thyrotoxicosis
Levothyroxine pt education
several weeks for symptoms to improve
Take empty stomach
Take 4h apart from antacids, iron, calcium supp
pick 1 brand n stick with it
Subclinical hypothyroidism definition
Elevated TSH (above upper ref range) with normal T4
Should you initiate hypothyroidism treatment?
TSH > 10 = probs sart levo 25
TSH < 10 = consider based on individual factors
Myxedema Coma Treatment
Levo IV 300-500 bolus, 75-100 IV maintenance until stable and start PO
Hydrocortisone 100mg Q8H IV until adrenal suppression ruled out
Supportive care
Myxedema Coma Symptoms
Hypothermia
Hypoventilation
Advanced stages of hypothyroid symptoms
delirium, coma
Grave’s Disease
autoimmune disorder with thyroid stimulating antibody acting on thyroid
Primary
Hyperthyroidism risk factors
Female
FH of autoimmune conditions
FH of hyperthyroidism
Pregnancy, some viral infections
Age = young n old, not so much middle
Hyperthyroidism clinical presentation
Tachycardia
heat intolerance
diarrhea
warm, smooth moist skin
fine hair
gynecomastia
**Exophalmos & retraction of eyelids ** Grave’s Disease
Hyperthyroidism treatment options
Reduce thyroid hormone:
Antithyroid drugs
Radioactive iodine
Surgery
Adjunctive options:
Symptomatic control ie BB, clonidine, Non-DHP CCBs
Antithyroid Drugs
Methimazole = generally preferred
Propylthiouricil (PTU) = pref in preg 1st trimester, thyroid storms
Onset: 4-6 wk response, 4-6month max response, 1-2 txm last
Who should use ATD?
> 40yrs old
low T4/T3 ratio ( < 20)
Small goiter < 50g
short duration disease < 6 month
no prev hx of relapse
therapy > 1-2yrs duration
low TSAb titers at BL
consider use pre-op prep 6-8wk before thyroidectomy
Patient education ATD
Side effects
Tell doc about rash, jaundice, acolic stool or dark urine, arthralgia, ab pain, nausea, fatigue, fever, pharyngitis
Who are ATD 1st line treatment for
preg, children, adolescents
Radioactive Iodine therapy info
consider in: “Hot nodules”, Toxic MNGs, Graves Disease
onset : weeks to see destruction
Kills gland tissue essentially
pretreat with ATD to prevent thyroid storm
When should iodine be stated after RAI?
3-7 days after to prevent interference of uptake of RAI in thyroid gland
RAI ADE & CI
CI = pregnancy
Short term ADE: Mild thyroidal tenderness, dysphagia
Long term ADE: Hypothyroidism
RAI Pros and Cons
Pro:
cure hyperthyroidism
Outpatient therapy
lowest cost adjust QOL
best for toxic nodules and multi nodular goiter
Con:
perm hypothyroidism in >60% pts
can worsen ophthalmopathy
preg deferred 6-12mnth no breastfeeding
Surgery thyroid
Consider pts with large gland >80g, severe ophthalmopathy, and lack of remission on Anti thyroid drug
adj therapy: pre-treat methimazole 6-8wk, iodides 10-14 day before surgery and propranolol severe weeks preop, and 7-10 days post op
Surgery pro and cons
Pro:
rapid, effective
thyroid cancer and nodules
Con:
permanent, invasive, scars
Iodides info
used as adj therapy
ADE: iodize = metallic taste, burning mouth and throat, salivary gland swelling
CI: Toxic MNG
DI: start 3-7 days after RAI
Who gets Treated for Subclinical Hyperthyroidism
TSH < 0.1 if age >65, or > 65 w/ Heart Disease, Osteoporosis, menopausal (not on estrogens or bisphos), hyperthyroid symptoms
If TSH 0.1-0.4 then consider treating
If < 65 n asymptomatic TSH < 0.1 then consider treating, 0.1-0.4 then observe
Thyroid storm
medical emergency, mortality ~ 20%
symptoms: > 103F, Tachycardia, tachypnea, dehydration, delirium, coma, nausea, vomiting, diarrhea.
lasts about 72hrs, up to 8 days
