Thyroid Flashcards
1
Q
Primary Hypothyroidism
A
- Low T4
- High TSH
2
Q
Secondary Hypothyroidism
A
- Low T4
- Low TSH
3
Q
Management of hypothyroidism
A
- Replacement with thyroid hormone and is lifelong
- Therapeutic goal is -.5-2.5
4
Q
Over-replacement
A
- Leads to low TSH
- S/S: affects bone density, cardiac complications
- Brand differences
5
Q
Levothyroxine tips
A
- Take on empty stomach
- Before increasing drug, check for angina, diarrhea, or malabsorption
- Long half-life
5
Q
Drug Interactions: Levothyroxine
A
- Avoid administering with: Iron, aluminum hydroxide, antacids, sucralfate, cimetidine, calcium supplements or soy milk, with bile acid sequestrants
- Anti-seizure meds may increase hepatic metabolism
- May effect warfarin dosing
6
Q
Levothyroxine follow-up
A
- Patients usually notice improvement in 2wk: Less facial puffiness, increased urination, improved energy
- Recheck TSH after 6wk and adjust dosage
- ** Recheck every 6wk until dosage regulated, then check annually
7
Q
Subclinical management of hypothyroidism
A
TSH concentration >10mU/L or antithyroid peroxidase antibody with a normal T4: treat with synthetic T4 to prevent progression to overt hypothyroidism
- treatment may be indicated in patients with TSH 5-10mU/L (T4 normal) if these are present: Goiter, nonspecific symptoms, cardiac disease or diabetes
8
Q
Graves Disease
A
- antithyroid meds
- Ablation with radioactive iodine
- Surgery: thyroidectomy
- Symptom management
9
Q
Antithyroid medications
A
- Methimazole (Tapazole)
- Propylthiouracil (PTU)
- Goal: Inhibit thyroid synthesis until thyroid stores are depleted and euthyroid state achieved (3-8wk)
- remission rates vary from 10-90%
- Reevaluate q3-6mo and check symptoms
- Treat reoccurence with anti-thyroid drugs
- – PTU drug of choice for pregnancy
10
Q
Graves: Propanolol
A
- Controls symptoms
- Initially 20mg BID
- Increase to 20-40mg BID-QID: Until improvement in tachycardia, tremor and diaphoresis and anxiety
- Continue until hyperthyroidism is resolved
- Does NOT impact thyroid hormone levels
11
Q
Antithyroid Drugs: TOC for
A
- Young adults
- Those with mild thyrotoxicosis, small goiters
- Those with fears of radioactive iodine
- Patients preparing for surgery or radioactive iodine Tx
12
Q
Graves: Agranulocytosis
A
- Uncommon but severe complication of antithyroid meds
- Presents in first 3mo of therapy
- S/S: Fever, sore throat, rash, arthralgia, myalgia
- Stop drug immediately and proceed to ED
- Practice implications: Baseline CBC-diff, and then at follow-up
13
Q
Monitoring antithyroid meds
A
- Baseline CBC-diff, LFT’s with bilirubin
- Monitor TSH q4-6wk
- Goal: normalize TSH
- If TSH remains low after 6mo of therapy, will likely recur once drugs stopped
- Refer for definitive treatment
14
Q
Radioactive Iodine
A
- Goal: Reduce the volume of functioning thyroid tissue
- used most frequently in older patients
- TOC: >20yo and those for whom Tx with antithyroid drugs has failed
- Not preferred for children, adolescents or women in reproductive years
- Contraindicated in pregnancy (U-Preg before, defer pregnancy 3-6mo after)
- Benefits: Definitive, easy, can be repeated
15
Q
radioactive iodine limitations
A
- May take many months to reverse
- Causes hypothyroidism
- Should be avoided in patients with Graves ophthalmopathy: May exacerbate
16
Q
Graves: Surgery indications
A
- Pregnancy
- Large goiters
- Refusal of radioactive iodine
- Coexisting suspicious nodules
- Failed previous Tx
17
Q
Graves Surgery benefits, limitations, and complications
A
Benefits: - Definitive Limitations: - Cost, invasive, causes hypothyroidism Complications: - hypothyroidism, vocal chord paralysis/hoarseness, transient or permanent hypocalcemia from hypoparathyroidism
18
Q
Subclinical hyperthyroidism: high risk
A
- If serum TSH <0.1mU/L, treat underlying cause of subclinical hyperthyroidism
- If the serum TSH 0.1-0.5m/L, treat if there is underlying CVD or if bone density is low
19
Q
Subclinical hyperthyroidism: Low risk
A
- Serum TSH <0.1: treat underlying cause if patient has S/S or if radioactive nucleotide uptake shows one or more focal areas
- Serum TSH 0.1-0.5: Observation appropriate and monitor labs q6mo
20
Q
Management: Graves Disease
A
- Check WBC periodically with antithyroid drug
- Free T4 and TSH q4-6wk initially, then q3-6mo until stable, then q6-12mo
- Hypothyroidism common months to years after I131 or thyroidectomy: Periodic TSH evaluation
- Patient and family education; lifelong follow-up, s/s of recurrences and plan
21
Q
Thyroiditis: Types
A
- Subacute thyroiditis (deQuervain’s thyroiditis)
- Postpartum thyroiditis
- Hashimoto’s thyroiditis (chronic lymphocytic thyroiditis)
22
Q
Subacute Thyroiditis (deQuervain’s thyroiditis)
A
- Sequelae of viral infection
- Severe pain in the neck, ears, and jaw; tender enlarged thyroid gland; fatigue
- Tends to remit spontaneously and reoccur several times
- Low TSH, high T3 and T4, followed by period of overt hypothyroidism, followed by normal thyroid function
- Treatment: symptomatic propanolol for palpitations; ASA or NSAIDs; if severe, may use steroids (prednisone)
23
Q
Postpartum Thyroiditis
A
- A painless thyroiditis with transient hyperthyroidism and hypothyroidism
- Auto-immune-mediated; increased anti-thyroid antibodies
- Suspect if weight loss faster tahn usual, mood changes, palpitations, “baby blues”
- Does NOT require aggressive treatment (symptoms may last up to a year)
- Close monitoring of TFT’s
- Beta-Blockers can be used in hyperthyroid phase with caution as they can cross over into breast milk
- Most patients will become euthyroid but up to 20-30% remain hypothyroid
- May have recurrences with subsequent pregnancies
- Need to differentiate from Graves’ Disease (low uptake of scan with postpartum thyroiditis) (Graves’ would have “hot” areas)
24
Q
Hashimoto’s Thyroiditis Facts
A
- Chronic, autoimmune, thyroiditis
- Most common thyroid disorder in US
- Associated with other autoimmune disorders
- Screen patients with personal or family Hx of auto-immunity with TSH
- Increased antibodies (similar to Graves’)
- – TPO levels increased by 95%
- – ATA increased by 60% (very non-specific)
25
Q
Hashimoto’s Thyroiditis: S/S
A
- Symptoms of hypothyroidism
- Thyroid gland is usually diffusely enlarged (goiter), firm, rubbery, finely nodular, irregular surface
- Pain usually not present
- Gland may be atrophic
26
Q
Hashimoto’s: Treatment
A
- Replace with synthetic T4
- If large goiter:
- – Suppress TSH with synthetic T4 to reduce size of goiter
- – If euthyroid (normal TSH, minimal or absent goiter), follow closely for the development of hypothyroidism
27
Q
Thyroid nodules and MNG: Facts
A
- The prevalence of cancer is higher in several groups and this needs to be a priority:
- – children
- – Adults 60
- – Patients with Hx of head and neck irradiation
- – Patients with a family Hx of thyroid Cancer
28
Q
Thyroid nodules and MNG: Labs
A
- TFTs (TSH and Free T4)
- Thyroid ultrasound
- – Preferred over MRI or CT for accuracy
- – Detect lesions as small as 2-3mm
- – Lesions may be solid, cystic, or mixed
- – Can’t distinguish between benign or malignant nodules
- – Can be used to monitor nodules
29
Q
Thyroid nodules and MNG: Biopsy
A
- US guided fine needle aspiration
- – Gold standard; reported as benign, malignant, or suspicious
- – Cytology done on any cystic fluid obtained
- ** 70% Benign (Thyroid adenomas)
- ** 10% follicular neoplasms (suspicious cytology)
- ** 5% malignant
- ** 15% nondiagnostic
30
Q
Thyroid nodules and MNG: PC of benign nodules
A
- Observation/monitoring q6-12mo
- Clinical exam: palpation
- US
- Monitor for atrial arrhythmias ans osteoporosis
- Suppression with synthetic T4
- More successful with patients with a MNG or diffuse nontoxic goiters
- Less successful in Tx of a single nodule
- Consider a 6mo trial to decrease TSH, shrink nodule
31
Q
Starting Dose of Levothyroxine
A
- 50-100mcg: if no CAD and 60yo
