Clincial Approach To Hypo And Hyperthyroidism Flashcards
Classic hypothyroidism symptoms
Tired and fatigues*
Constipation
Cold insensitivity*
Dry skin and thickened/brittle nails
Myxedema
Depression
Hoarseness of voice and decreased hearing/vision
Difficulty concentrating/ memory impairment
Decreased libido
Dry hair/ loss of hair
Weight gain*
Arthralgia
- = most common
Classic hypothyroidism signs and lab results
Clincial signs
- bradycardia
- edema
- diastolic HTN
- goiter
- delayed DTRs
- macroglossia
- normocytic anemia
- pericardial effusion
Lab results:
- elevated CRP
- hyperprolactinemia
- hyponatremia
- increased creatine kinase
- increased total and LDL cholesterol
- increased TAGs
- proteinuria
Work up of suspected hypothyroidism
1) measure TSH levels
- for hypothyroidism = >5.5 mIU
2) measure for T4 serum
- if T4 is below normal ranges = primary hypothyroidism
- if T4 is within normal range = subclinical hypothyroidism
- if T4 is above normal range = secondary or tertiary hypothyroidism
3) in order to diagnosis must get two measurements of both TSH and T4 levels at different times that show increased TSH and decreased T4
Causes for increased TSH with decreased free T4
Autoimmune hypothyroidism
Iodine severe deficiency or relative excess
Postradioiodine of thyroid, head, neck regions or thyroidectomy
Drugs (amiodarone, lithium, etc)
Causes for increased TSH and normal free thyroxine
Subclinical hypothyroidism
(Essentially mild hypothyroidism)
Assay interference
TRH/TSH resistance syndrome
Adrenal insufficiency
Causes of increased TSH with increased free thyroxine
Non-adherence to therapy
Central/secondary hyperthyroidism
Treatment of hypothyroidism
Taper up T4 (levothyroxine dose)
- start with 1.5-1.8 mcg per kg of body weight and measure levels 4-12 weeks (good dose = TSH is normal)
- then continue to measure every 6 months when stable levels
Population considerations:
- start with 25 ug per day for hypothyroidism patients who have cardiac symptoms or are elderly (>60). (Dont go to high initially to prevent arrthymias or CAD)
- pregnant women require a 30% increase in current thyroxine dose while pregnant (prevents creatism)
Special considerations when taking levothyroxine
Dont take with food
- decreases absorption
Dont take together with calcium carbonate/ferrous sulfate/ PPIs/ antacids/orlistat and sucralfate
- decrease absorption and should spread these medications out at least 4 hrs apart
Concomitant use of Sertaline/phenobarbital/carbamazepine/phenytoin/rifampin
- decrease absorption so need to use higher dose while on these
- TCA’s and SSRIs in general do this a lot
Patients with celiac, autoimmune atrophied gastritis, an H. Pylori infections need to be treated for these and well controlled first
Being pregnant or using oral estrogen contraceptives requires higher dose
Possible causes of persistent hypothyroidism even with normal TSH levels from treatment
Adrenal insurer
B12/iron anemia
CKD
Depression uncontrolled
Liver disease
OSA
Vitamin D deficiency
Viral infection from:
- mono
- AIDS
- Lyme disease
When to consult an endocrinologist for hypothyroidism
Children and infant cases
Patients are consistently refractory to treatment
Patients who are pregnant or women planning on getting pregnant
Patients with cardiac disease
Presence of goiter or adrenal/pituitary concomitant disorders
Patient has unusual causes of hypothyroidism
Common symptoms in hyperthyroidism
Fatigue and tiredness*
Nervousness/anxiety/tremors*
Heart palpitation*
Heat intolerance*
Weight loss despite increased appetite*
Unusual menstrual cycle/amenorrhea
Difficulty concentrating/memory loss
Irritability
Rashes over shins that are refractory with steroid creams
Nausea/vomiting and hyper defication without diarrhea
Chronic or with Graves’ disease = irritation in eyes, eye swelling and proptosis (eyelid retraction and lag)
- = most common
Clinical signs of hyperthyroidism
Heart palpitations and tachycardia
Tremors/jitteriness
Diaphroesis
Weight loss
Peripheral edema (only with CHF also)
Onycholysis (Plummer nails)
Pretibial myexedma with thyroid dermopathy and clubbing of nails. Also may show patchy vitiligo**
(Really only seen with Graves’ disease) ‘
Blurred or double vision with exophthalmos and periorbital edema (pathoginomic for graves)**
High fever (if in thyroid storm)
4/4 reflexes
Psychosis and pressured speech (severe only0
Work up of hyperthyroidism
1) measurement of TSH and free T4 or T index
- hyperthyroidism = low TSH and high T4 or free T index
2) either radioactive iodide uptake test or thyroid ultrasound and TSI assay/titer (can do both but usually only one or the other)
- Graves’ disease = high diffuse radioiodine uptake and/or TSI positive with enlarged thyroid
- toxic multi nodular goiter or adenoma = high focal radioiodine uptake and/or TSI negative with enlarged thyroid
(Multi nodular goiter = multiple focal patches; adenoma = one focal patch)
What should you suspect when hyperthyroidism comes back with lab values of high T4 AND TSH and T3 levels
(Everything high)
TSH-secreting pituitary adenoma
What should be suspected in hyperthyroidism with low uptake of radioactive iodine but normal hyperthyroid lab values?
Thryoditis, ectopic thyroid tissue/hormone
What conditions can mimic hyperthyroidism
Estrogen excess:
- shows high estrogen and low GnRH as well as normal TSH levels
- also shows elevated T3 but NOT T4
Non-thyroidal illness syndrome
- shows low TSH and T3
- shows normal T4
Glucocorticoid or dopamine therapy
- shows low TSH and normal everything else
What are the categories in the Burch-Wartofsky score criteria for thyroid storm
Thermoregulation dysfunction
CNS effects
GI-hepatic dysfunction
Cardiovascular dysfunction
CHF present and if so exacerbation of symptoms
Precipitation history of past thyroid storm
- *look at picture cards for exact table but needs a score of 45 or greater to mean 100% thyroid storm
- 25-44 = possible impending storm
- <25 = no storm
Possible treatment for hyperthyroidism
BBs (atenolol and propranolol most use)
- dosage = 25-100mg orally (atenolol)
- dosage = 10-40mg orally (propranolol)
- DONT give to CHF patients
- use atenolol over propranolol in asthma/COPD
Antithyroid medications
- methimazole (5-120mg orally)
(CONTRAINDICATED in 1st trimester of pregnancy and can cause dose-related agranulocytosis sometimes)
- propylthiouracil (PTU) (50-300mg orally)
(Better in 1st trimester of pregnancy, however casues higher risk in liver failure patients. Also causes dose-independent agranulocytosis and ANCA assocaited vasculitis) - radioactive iodine (10-30 millicurie)
(CONTRAINDICATED in Graves’ disease or patients who are pregnant/nursing. Also may aggravate hyperthyroidism)
(** always causes hypothyroidism!!)
Ancillary agents for hyperthyroidism
Not first line and dont actually treat causes of hyperthyroidism
1) cholestyramine
- binds thyroid hormones and increases fecal excretion
- causes constipation and diarrhea
2) glucocorticoids (prednisone and hydrocortisone)
- reduces T4 -> T3 conversion to slow down effects
- **1st line if patient is in thyroid storm
- causes hyperglycemia in diabetes patients
3) NSAIDs
- treats pain in subacute thryoditis
- causes nephrotoxicity and GI bleeding in high doses
4) supersaturated potassium iodide
- transiently turns off hyperthyroidism
- give at least one hour AFTER use of anti-thyroid agent
- NEVER give before radioactive iodine treatments (can exacerbate hyperthyroidism into thyroid storm)
3 treatment options for Graves’ disease
1) antithyroid medications
- methimazole or PTU
2) radioactive iodine ablation
3) thyroidectomy
Treatment for thyroid storm
Note all steps are done
1) supportive treatment
- airway maintenance
- oxygen and IV fluids
- cooling blankets**
(DONT give NSAIDs for fever, they increase free T4 and T3 levels in the body)
2) inhibit T3/T4 synthesis
- methimazole or PTU
3) inhibit T3/T4 release
- saturation solution of potassium iodide after 1 hr of being step #2
4) heart rate control
- esmolol, propranolol or metoprolol
5) inhibit T3/T4 conversion
- hydrocortisone
