thyroid and parathyroid Flashcards
what is the function of the thyroid gland?
secrete thyroid hormone
secrete calcitonin
Thyroglobulin
Protein that synthesizes and stores T3 and T4
Thyroid hormones
T3 (3,5,3’-triiodothyronine)
T4 (thyroxine)*
Hyperthalamus
releases TRH > TSH > T3/T4 to liver
…and
circulatory system –> which inhibits anterior pituitary gland and hypothalamus
2 causes of hypothyroidism
Generalized metabolic slowing
accumulation of matrix substances
S/s of Generalized metabolic slowing of hypothyroidism
Fatigue, weakness Cold intolerance Weight gain Cognitive dysfunction Constipation Slow movement/speech Delayed relaxation DTRs Bradycardia
s/s of accumulation of matrix substances of hypothyroidism
Dry skin Hoarseness Edema Coarse skin Puffy facies Loss of eyebrows Periorbital edema Tongue enlargement
other s/s of hypothyroidism
Decreased hearing Myalgias/arthralgias/paresthesias Depression Menstrual changes Pubertal delay Diastolic HTN Pleural and pericardial effusions Ascites Galactorrhea
PE for pt suspected of hypothyroidism includes:
Vitals Skin HEENT Neck Cardiac Respiratory Abdominal GU Neuro Extremity
PE exam findings for hypothyroidism
Vitals - bradycardia, HTN
respiratory - dec CO, dyspnea
skin - dry, hair loss, brittle nails, vitiligo, alopecia
abd- ascites, hypoactive bowel sounds, constipation
extremity- edema, carpal tunnel syndrome d/t edema
Labs for hypothyroidism
TSH (if only for screening):
**Free T4 (most important)
T3
other: BMP (Na & Cr), lipids (elevated), drug levels
what will TSH look like in hypothyroidism?
TSH will be high
upper limit of normal, usu. 4-5mU/L
what will T4 and TSH look like in primary hypothyroidism?
T4 = low TSH = high
what will T4 and TSH look like in subclinical hypothyroidism?
T4 = normal TSH = high
Anti TPO antibody expected result…
Elevated in Hashimoto’s thyroiditis
Elevated in Grave’s disease
Anti thyroglobulin antibody expected result…
Elevated in Hashimoto’s thyroiditis
Elevated in Grave’s disease
Thyroid Stimulating Immunoglobulin (TSH Receptor Antibody) expected result…
Grave’s disease (65%)
when are you NOT concerned if pt has anti-thyroid antibodies?
if pt is asymptomatic
hypothyroidism etiology?
Autoimmune thyroiditis (Hashimoto’s) Iatrogenic (radiation, sx) Iodine deficiency or excess Meds Transient Infiltrative (rare) Congenital
which pt’s are at increased risk for hypothyroidism?
Goiter History of autoimmune dz Previous radioactive iodine therapy Hx head/neck irradiation Family hx thyroid disease Meds that impair thyroid fx
also, pt’s with lab or radiologic abnormalities that could be caused by hypothyroidism
which meds are known to impair thyroid function?
Lithium, amiodorone, aminoglutethimide, interferon α, thalidomide, betaroxine, stavudine
what is the main tx & management for hypothyroidism?
Synthetic thyroxine (T4) replacement
to achieve and maintain euthyroid state
what meds are used to tx hypothyroidism? and why is it a good functional med?
Levothroid, Levoxyl, Synthroid
High absorption, long half life
what is the average dose for Levothroid, Levoxyl, Synthroid?
in elderly?
hx Coronary hx dz?
dose avg. 1.6mcg/kg/day
elderly - 25-50mc/kg/day
hx Coronary heart dz - 25mc/kg/day
goals of tx for hypothyroidism?
Symptom relief
Normalization of TSH secretion
If applicable, decrease in goiter size
how often should you monitor pt when administering new medications?
q 6weeks
what are other tx options available for hypothyroidism? why are they not 1st line?
T3 (Cytomel)/T4 combo therapy (bad bc highly variable w/short half life)
Dessicated thyroid extract (Armour Thyroid, Nature Throid) (absorption/metabolized variable)
how many pt’s w/subclinical hypothyroidism progress to overt hypothyroidism?
1/3 to 1/2
possible assoc. with subclinical hypothyroidism?
CV disease
NAFLD
Neuropsychiatric
Reproductive
tx for subclinical hypothyroidism?
TSH > 10 –> supplement w/thyroid hormone
TSH ULN - 10 –> clinical presentation??
(but free T4 normal)
etiology of hyperthyroidism?
MC = Autoimmune thyroid disease
Autonomous thyroid tissue
TSH-mediated
hyperthyroidism
Human chorionic gonadotropin-mediated hyperthyroidism
what dz’s are considered Autoimmune thyroid diseases?
Graves’ disease
Hashimoto’s thyroiditis
what dz’s are considered autonomous thyroid tissue?
Toxic adenoma
Toxic multinodular goiter
what dz’s are considered TSH-mediated hyperthyroidism?
TSH-producing pituitary adenoma (rare)
Non-neoplastic TSH-mediated hyperthyroidism
clinical presentation for hyperthyroidism?
Skin changes Stare and lid lag **Graves’ ophthalmopathy (specific finding) Cardiovascular (tachy, Afib) Low total and HDL cholesterol Impaired glucose tolerance Dyspnea and DOE Weight loss Normochromic, normocytic anemia Genitourinary Bone changes Neuropsychiatric change
labs for hyperthyroidism?
TSH (low), T3 & T4 (high)
other: *TSH receptor antibody
&
antithyroglobulin antibody, antithyroperoxidase antibodies, ANA, anti-dsDNA antibodies
diagnostic tools for hyperthyroidism?
24 hour radioiodine uptake and scan
Contraindications for 24 hour radioiodine uptake and scan
pregnancy & breastfeeding
what does high uptake and low uptake indicate on 24 hour radioiodine uptake and scan?
High uptake = increased hormone synthesis
Low uptake = inflammation/destruction of thyroid gland or extrathyroidal source of thyroid hormone
Tx options for hyperthyroidism?
Beta-blockers Thionamides (Methimazole Propylthiouracil (PTU)) Radioiodine ablation Surgery
subacute thyroiditis aka…
granulomatous, de Quervain’s, giant cell thyroiditis
clinical presentation for subacute thyroiditis?
p/w acute symptoms or silently
Common in young/middle-aged females
assoc. w/viral illness
acutely painful glandular enlargement with dysphagia
who is subacute thyroiditis dx’d
clinical w/labs
how is subacute thyroiditis tx’d?
with anti-inflammatories (ASA, NSAIDS, prednisone) and symptom management
etiology of thyroiditis?
- thyroiditis:
subacute granulomatous (de Quervain’s) thyroiditis,
painless thyroiditis, postpartum thyroiditis, amiodarone-induced, radiation thyroiditis, palpation thyroiditis - Exogenous thyroid hormone intake: excessive replacement therapy, intentional suppressive therapy
during 1st trimester pregnancy, what is the preferred med in pregnancy?
propylthiouracil
what is a thyroid storm?
Rare, acute endocrine emergency
w/ high mortality usu. results from an acute event
risk factors for thyroid storm?
Surgery Trauma Infection Iodine adminsitration Childbirth Withdrawal of antithyroid meds MI, CVA, PE
clinical presentation for thyroid storm?
Cardiac (tachy, CHF, hypotension, arrhythmia) Fever Agitation, anxiety, delirium, psychosis Stupor, coma N/V/D, abd pain Hepatic failure/jaundice Goiter Ophthalmopathy, lid lag Hand tremor Warm, moist skin
diagnosis of thyroid storm?
Clinical presentation of severe, life-threatening symptoms
+
Low TSH, high free T4/T3
thyroid storm tx?
ICU
Meds: Beta-blocker Thionamide Iodine solution Glucocorticoids Bile acid sequestrants
DEFINITIVE THERAPY (ablation therapy)
how does BB for thyroid storm work?
symptom control
how does thionamide for thyroid storm work?
block new hormone synthesis
how does iodine solution for thyroid storm work?
blocks release of thyroid hormone from gland
how does glucocorticoids for thyroid storm work?
reduces T4 to T3 conversion, promotes vasomotor stability, treat associated related adrenal insufficiency
how does bile acid sequestrants for thyroid storm work?
decrease enterohepatic recycling of thyroid hormones
benign etiology of thyroid nodules?
Multinodular goiter
Hashimoto’s thyroiditis
Cysts
Follicular adenomas
malignant etiology of thyroid nodules?
Papillary carcinoma Follicular carcinoma Medullary carcinoma Anaplastic carcinoma Primary thyroid lymphoma Metastatic carcinoma (breast, renal cell)
thyroid nodule cancer concerning factors?
kids, men, adults <30 y/o, >60 y/o hx of head/neck radiation hx hematopoeitic stem cell transplant family hx thyroid cancer size (larger)
what is the most important lab value to evaluate w/ workup of thyroid nodules?
TSH
what imaging do you order if thyroid nodule found?
thyroid ultrasound
which is worse “hot or cold” nodule on radioactive scan?
COLD
next step for solitary nodule with low TSH…
thyroid scan
next step for solitary nodule with normal TSH…
FNA, consider US
what type of nodule do you NOT want to bx? (major contraindication)
if it is a “HOT” nodule
what is a FNA bx?
Procedure of choice to evaluate nodules and select surgical candidates
done by palpation or U/s guided in office
large nodules do multiple samples
what size of nodule do you do a FNA?
≥ 1 cm unless high risk hx then >5mm
what findings are worrisome and indicative for FNA?
lymph nodes, micro-calcifications, solid masses on u/s
Management of benign FNA results?
Repeat U/S 6-18 months to assess stability
Growth > 20% - repeat FNA
incidence of thyroid carcinoma?
Incidence & mortality increase with age
More common in females
Worse prognosis:
< age 20
> age 45
Male gender
risk factors for thyroid carcinoma?
History of childhood head or neck irradiation
Thyroid cancer in first degree relative
Large nodule size (≥ 4 cm)
types of thyroid cancer?
Papillary (~85%) Follicular (~12%) Anaplastic (<3%) Medullary (~1-2%) Primary thyroid lymphoma (<2%) Mets from other site
Tx for thyroid carcinoma
Surgery (near total thyroidectomy) TSH Suppression (Levothyroxine) Radioiodine ablation Chemotherapy Palliative external radiotherapy
monitoring for thyroid carcinoma post-tx management
Serum thyroglobulin level, anti-thyroglobulin antibodies
Neck ultrasound
Serum TSH level
+/- Diagnostic whole body radioiodine scan
MRI, CT, PET as appropriate
what is the fx of the parathyroid gland?
Parathyroid hormone secretion to help regulate calcium homeostasis
Also helps regulate phosphate
Negative feedback w/calcium sensing receptor on surface of parathyroid cells
slide 54
54
what are examples of parathyroid disease?
Hypoparathyroidism
Hyperparathyroidism
MC reason for hypoparathyroidism?
Acquired, usually occurs post-thyroidectomy
other: autoimmune, congenital
Clinical presentation
sxs assoc. w/low Calcium
Tetany Muscle cramps Caropopedal spasm Chvostek sign Trousseau phenomenon Cataracts Thin/brittle nails Dry, scaly skin AMS convulsions
hypoparathyroidism lab values…
serum calcium (low) serum phosphate (high) urinary calcium (low) alkaline phosphatase (norm) PTH (low) Mg (low to norm)
Tx for hypoparathyroidism?
Emergency treatment for acute tetany:
IV calcium gluconate plus oral calcitriol (wean to oral calcium)
Airway maintenance
maintenance tx for hypoparathyroidism?
Oral calcium and vitamin D supplementation
Avoid hypercalcemia
2nd line tx: recombinant hPTH
Hyperparathyroidism etiology
Primary hyperparathyroidism
Secondary or tertiary hyperparathyroidism
Multiple endocrine neoplasia (MEN)
etiology for Primary hyperparathyroidism
Parathyroid adenoma (MC) Parathyroid hyperplasia Parathyroid carcinoma (rare)
Secondary or tertiary hyperparathyroidism etiology
- Chronic renal failure
(Hyperphosphatemia and ↓renal vitamin D production → ↓ ionized calcium, which stimulates the parathyroids) - Renal osteodystrophy
clinical presentation of Hyperparathyroidism
Asymptomatic hypercalcemia
“bones, stones, abdominal groans, and psychiatric moans”
clinical presentation of hyperparathyroidism?
Renal MSK GI Neurologic CV
diagnostics for hyperparathyroidism?
Elevated calcium
Elevated serum PTH level
Urinary calcium excretion
Tx for hyperparathyroidism?
Surgical resection is definitive = Parathyroidectomy
Conservative treatment: Physical activity Drink adequate fluids Avoid lithium and HCTZ Restrict calcium intake to 1000 mg/day Vitamin D 400-600 IU daily Monitor
conservative tx of of Primary hyperparathyroidism?
IV bisphosphonates can temporarily ↓ hypercalcemia and treat bone pain
Zoledronic acid (Reclast)
Secondary or tertiary hyperparathyroidism conservative tx?
Cinacalcet (Sensipar), paricalcitol (Zemplar)
