Thyroid
In the US, hypothyroidism is most commonly associated with what kind of disease.
Globally, what is hypothyroidism due to?
Autoimmune disorder
Iodine deficiency
Graves disease, toxic adenoma, toxic multinodular goiter
What are the most common thyroid cancers?
papillary>follicular
Many patients with this condition are asymptomatic and hypercalcemia is discovered incidentally on routine CMP.
Of those who are symptomatic, what are the most notable symptoms?
Hyperparathyroidism
Bones, stones, abdominal groans, psychic moans, and fatigue overtones.
Bone loss, kidney stones, psychiatric disturbances, abdominal pain, and fatigue.
Iatrogenic: thyroidectomy, radioiodine therapy, radiation
Iodine deficiency
Drugs: lithium, amiodorone
An autoimmune disorder characterized by the formation of autoantibodies that bind to TSH receptors and stimulate hyperfunction.
Occurs more often in women than men, onset 20-40yrs, runs in families.
Graves disease
Papillary thyroid carcinoma is the most common thyroid malignancy. What are some of its characteristics?
Slow growing, remains confined to thyroid and regional lymph nodes for year, least likely to metastasize
Primary hyperthyroidism can cause symptoms that we normall associate with DM. What are they?
Polyuria, polydipsia, hypertension, confusion, lethargy, fatigue
What is secondary hypothyroidism? Is it common?
Lack of pituitary TSH (hypopituitarism)
Not common
State some signs/symptoms of hyperthyroidism.
Nervousness, restlessness, heat intolerance, seating, fatigue, weakness, muscle cramps, increased appetite, weight loss, palpitations, exophthalmos
What are risk factors for developing papillary thyroid carcinoma?
Increased lifetime radiation exposure to head and neck, childhood exposure to radiation
What are the cardiovascular findings in patients with hyperparathyroidism-hypercalcemia
Hypertension, prolonged P-R interval, shortened Q-T interval, bradyarrhythmia, heart block, asystole
Name several symptoms of hypothyroidism
Fatigue, cold intolerance, bradycardia, weight gain despite lack of appetite, constipation, hoarseness, hair loss/dry brittle hair, dry/itchy sin, memory loss, puffiness of face, anemia, delayed reflexes, goiter, increased cholesterol and hyponatremia
Grave's disease in known to have an increased risk of developing these conditions
Addison's, alopecia areata, celiac, T1DM, MG, cardiomyopathy, hypokalemic periodic paralysis
What are some characteristics of follicular thyroid carcinoma?
More aggressive than papillary carcinoma, doesn't typically spread to the lymph nodes, but may metastasize to lung, bone, and other distant sites, may invade BVs, more aggressive in older pts.
Why is hyperparathyroidism dangerous in pregnancy?
~70% of women experience nephrolithiasis, hyperememis, pancreatisis, muscle weakness, cognitive changes and hypercalcemic crisis
Fetal demise, preterm delivery, low birth weight, postpartum neonatal tetany, permanent hypothyroidism
What initial labs are appropriate to order if you suspect hypothyroidism?
When labs come back, and these numbers are out of range, what labs can you order next?
1. TSH, FT4
2. Fasting lipid panel (looking for hypercholesteremia) and Antithyroglobulin and Antithyroperoxidase antibodies
What labs are ordered in a suspected Graves disease case? What lab values are you expected to see? (high/low)
TSH: low, except pituitary hyperplasia and TSH secreting pituitary tumor
FT4: elevated
T3: elevated
Thyroid antithyroglobulin: elevated
TSH receptor antibody agonist: positive
Thyroid-stimulating immunoglobulin: positive
This thyroid carcinoma produces calcitonin and is found in people with MEN2A
What labs would you order if you suspect hyperparathyroidism, and what values would you expect?
PTH & CMP: PTH elevated despite high serum calcium, serum phosphate low-normal, look at creatinine to eval renal injury/failure
Ionized calcium vs serum calcium levels: serum calcium >10.5mg/dL, ionized calcium 5.4mg/dL or 1.4mmol/L is considered hypercalcemia
24hr urine calcium excretion: <50mg calcium in urine or calcium creatine calcium clearance of <.01 suggests familial hypocalciuric hypercalcemia
Check serum Vit D (25-OH vit D)
A patient comes in with complaints of fatigue and gradual weight gain over the last 2 months. What initial labs would you order, and what do you expect to see if the patient has hypothyroidism?
TSH: elevated serum TSH due to lack of negative feedback
FTH: low to low-normal
What are the medications given to treat hyperthyroidism?
Which thiamide is preferred due to its lower risk of harm and less frequent dosing/fewer pills?
Propanolol to treat symptoms of tachycardia, tremor, diophoresis, and anxiety
Thiamides: MMI and PTU (preg cat D, monitor for agranulocytosis)
MMI low 5-10mg, moderate 10-20mg, severe 20-40mg
Anaplastic thyroid carcinoma
What tests are ordered to check bone health?
Wrist, spine, and hip DEXA <-2.5 suggest osteoporosis
ALP will be elevated if bone disease is present
These tests are ordered to confirm Hashimoto's thyroiditis.
Thyroid antibodies
Explain how we treat hyperthyroidism in pts using MMI and I-131.
Why do we discontinue MMI 4 days prior to I-131 treatment?
Reduce dose as hyperthyroidism resolves (watch FT4)
Treat with I-131 and resume low dose after 3 days
Discontinue about 4 weeks after I-131 therapy if pt is euthyroid
What are the two categories of goiters?
How do we evaluate goiters?
Multinodular and diffuse
Check TSH, T3, T4 and perform thyroid scintigraphy to check for hot/cold spots
Perform thyroid ultrasound to look for signs of thyroid cancer: gland asymmetry, larger goiter, palpable thyroid nodules, rapid growth or compressive symptoms
Match the lab abnormalities with the three types of HPT
A: increased serum calcium, phosphorus low-normal, calcinuria
B: Low-normal serum calcium, high phosphorus
C: high calcium and phosphorus
A: primary HPT
B: Secondary HPT
C: Tertiary HPT
What medication is used to treat hypothyroidism? How do we monitor patient to make sure dosage is appropriate?
Levothyroxine
Monitor TSH to check for correct dosage. Monitor new symptoms of hypothyroidism or hyperthyroidism.
Pt comes into the clinic with tremors, weight loss, excessive sweating, and increased anxiety over the last several weeks. She mentions she feels a fluttering sensation in her chest and feels generally exhausted. She also noticed a bump near her throat several months ago. What do you suspect in the problem, and how would you test for it?
Toxic solitary nodule
Dx: Labs TSH and T3/FT4 (low TSH, T3>FT4), thyroid uptake test shows "hot spot"
Do goiters indicate hypothyroid or hyperthyroid?
Goiters can indicate both hypo and hyper, as well as euthyroid conditions. Get a good history and determine how goiter affects pt.
How do we define subclinical hypothyroidism?
What factors do we use to determine treatment?
Defined as a TSH that is higher than normal, but FT4 is within normal range.
We consider pt age <65, TSH level (>6.9, 7-9.9, <10), and symptoms of hypothyroidism.
A 72 yr old female patient comes in with tachycardia and complains of muscle cramps. Patient notes she's using the fan more often and can't do yard work anymore as it's much too hot. On PE, you note bilateral edematous and scaly regions on her lower legs. You palpate the thyroid and feel a "bag of marbles".
What condition do you suspect and what labs do you order after her initial checkup?
What are some risk factors associated with this disease?
Toxic multinodular goiter
Labs: TSH FT4 T3, thryoid uptake scan
Increased risk for arrythmias (Afib) and heart failure, thyroid cancer found in 18% of cases (need thyroidectomy)
Explain euthyroid sick syndrome (non thyroid illness syndrome)
Occurs in critically ill patients because sever stress effects peripheral conversion, making more thyroid hormone active. TSH levels will be lower.
Recheck after pt has been recovered (6 weeks)
What are some considerations when medicating with levothyroxine?
1. Start low (healthy pts 25-75mcg) and gradually increase (average adult dose 112-125 micrograms)
2. Take on empty stomach, avoid calcium, antacids, and iron for several hours.
3. Monitor for hyperthyroidism
4. Increase dose 30% in pregnancy (initial dose 10-150mcg)
5. Contraindicated in pts with CAD, can lead to CAD and CHF, >60/CAD start 25-50mcg.
OSteoporosis, cardiac arrhythmias, heart failure, opthalmopathy, anbd thyroid storm are all complications of what disease?
Hyperthyroidism
PTH released by the parathyroid gland works opposite of what hormone secreted from parafollicular cells in the thyroid?
Calcitonin
Cretinism occurs due to what? What are some signs/symptoms of cretinism?
Hypothyroidism during pregnancy.
S/S: Short stature, protruding tongue, intellectual disability, constipation, hoarse cry, somnolence, feeding problems.
A 36 yr old female presents to the ER with fever of 102, delirium, n/v, abdominal pain, HR of 120, and hypotension. You learn she recently gave birth 2 weeks ago. You order a CBC with slightly elevated WBCs, otherwise nonremarkable. You were able to obtain a medical history from her husband who mentions her mother had her thyroid removed years ago. You are concerned about infection, but what other condition might you be concerned with?
Thyroid storm
What three ways does PTH stimulate elevated serum calcium?
Which ion moves opposite of calcium in the nephron?
2. Promotes 1alpha hydroxylase to make Vit D which stimulates calcium and phosphorus uptake in the intestines.
3. Promotes calcium reabsorption in the distal convuluted tubule, and phosphorus excretion in the proximal tubule
Pt comes into the ER with severe lethargy and confusion. Pt is bradycardic, hypotensive, and began seizing in the ambulance. You get a call from a family member who states the pt has a history of asthma and Hashimoto's, and that she hasn't been taking her medications because they were too expensive to refill. What is this condition and how would you treat it?
Myxedema Crisis: Levothyroxine loading dose, IV fluids, warm blankies, adrenal insufficiency treated with hydrocortisone, possible intubation
Signs/symptoms of thyroid carcinomas?
Palpable, firm, non-tender nodule in thyroid
most are asymptomatic, but advanced can lead to dysphagia, hoarseness, dyspnea, mets to the lungs
These account for 90% of hypercalcemia cases
Primary hyperparathyroidism and malignancy
What are the most common kinds of thyroid cancers?
Papillary>Follicular
A 30 year old female patient comes into the clinic with throat/neck pain and difficulty swallowing. The patient has a low grade fever of 101.1 and reports weakness and fatigue. You learn the patient recently had a URI several weeks ago. Upon PE on the neck, the pt winces in pain when you palpate her thyroid. What do you suspect, and how do you treat?
Subacute thyroiditis
NSAIDs, steroids, T4 if having signs of hypothyroidism, propanolol if hyperthyroidism
What are the M/C etiologies of primary hyperparathyroidism?
Hypersecretion by single parathyroid adenoma or hyperplasia by two or more parathyroid glands
What common vitamin can cause thyroid levels to be falsely elevated?
Biotin
Infection of the thyroid, usually bacterial, seen as an enlarged growth on the neck. Treated with abx and I&D
Multiglandular hyperparathyroidism is usually the initial manifestation of this genetic disorder.
After removal, about how many pts have recurrent HPT in 10 yrs following surgery?
MEN1, 50%
What tests do we order to evaluate thyroid nodules?
Fine needle aspiration FNA biopsy: best dx method for thyroid cancer
Thyroid uptake scan: cold spots point to malignancy
US: useful in assisting FNA, thyroid monitoring after surgery, etc
Tamoxifen is used to treat this rare condition of stony hard growth/enlargement in the neck that can cause adherence to proximal tissues and symptoms of compression.
Riedel thyroiditis
This rare condition is associated with severe hypercalcemia, and 50% are palpable on PE.