your thyroid and you notes from an iodine laden gland
Download
Skip this Video
Download Presentation
your thyroid and you: notes from an iodine-laden gland

Loading in 2 Seconds...

play fullscreen
1 / 36

your thyroid and you: notes from an iodine-laden gland - PowerPoint PPT Presentation


  • 60 Views
  • Uploaded on

your thyroid and you: notes from an iodine-laden gland. Oliver Z. Graham, MD UpToDate-Certified Endocrinologist Department of Internal Medicine. The Agenda. Differential Diagnosis of hypo and hyperthyroidism Dosing Levothyroxine Management of Hyperthyroidism

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' your thyroid and you: notes from an iodine-laden gland ' - luther


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
your thyroid and you notes from an iodine laden gland

your thyroid and you: notes from an iodine-laden gland

Oliver Z. Graham, MD

UpToDate-Certified Endocrinologist

Department of Internal Medicine

the agenda
The Agenda
  • Differential Diagnosis of hypo and hyperthyroidism
  • Dosing Levothyroxine
  • Management of Hyperthyroidism
  • Subclinical Hypo and Hyperthyroid
  • Ordering Thyroid Antibodies
  • When to get FT4, FT3
screening for thyroid disease
Screening for thyroid disease
  • Very controversial subject
  • American Thyroid Association
    • Check TSH at age 35 and every 5 years afterwards
  • USPTS
    • Do not perform routine screening
  • Clinical consensus group
    • Reasonable to check TSH in women after 60 years old, also in those with risk for thyroid dysfunction (DM 1 or other autoimmune disease, +FH)
    • Also reasonable to screen all pregnant women
case study 1
Case study #1
  • A 54 YO woman presents with fatigue, constipation and cold intolerance.
  • TSH 66 (0.34-5.6)
  • Does she need any further workup?
  • How would you start thyroid replacement therapy?
differential hypothyroidism
Differential Hypothyroidism
  • Primary Hypothyroidism (95%)
    • Idiopathic/Hashimoto’s (most common)
    • Post radiation/thyroidectomy
    • Late stage fibrous thyroiditis
    • Drugs (lithium/interferon/amiodarone)
    • Infiltrative diseases
  • Secondary Hypothyroidism (5%)
    • Pituitary or hypothalamic tumor
    • Pituitary necrosis
elevated tsh low ft4 what do i do now
Elevated TSH, Low FT4 – What do I do now?
  • Is patient on amiodarone/lithium/interferon?
  • Examine thyroid
    • In Hashimoto’s, exam usually unremarkable
  • Start treatment
levothyroxine dose in hypothyroidism
Levothyroxine dose in hypothyroidism
  • Usual dose in healthy adult 1.6 mcg/kg
    • typical dose 100-150 mcg/day
  • Usual dose in elderly 1 mcg/kg
  • Pregnancy – thyroxine requirements may be > 50% higher
initiating treatment in hypothyroidism
Initiating Treatment in Hypothyroidism
  • If healthy patient with high TSH, can start at higher dose (50-100 mcg/daily)
  • If healthy patient with mild elevation TSH, start 25-50 mcg/day
  • In elderly, cardiovascular disease 
    • Levothyroxine 25-50 mcg/day
    • Check TSH q6 weeks, increase by 25-50 mcg until TSH normal
case study 2
Case study #2
  • A 32 YO woman presents with fatigue, constipation, cold intolerance, dry skin and difficulty with concentration.
  • TSH 0.37 (0.34-5.6)
  • Does she need any further workup?
case study 2 cont
Case study #2, cont
  • A 32 YO woman presents with fatigue, constipation, cold intolerance, dry skin and difficulty with concentration.
  • TSH 0.37 (0.34-5.6)
  • FT4 0.23 (0.58-1.65)
  • Does she need any further workup?
case study 2 cont1
Case study #2, cont
  • She also reports galactorrhea, amennorhea and hot flashes.
  • TSH 0.37 (0.34-5.6)
  • FT4 0.23 (0.58-1.65)
  • Prolactin level 1056 (5-20)
  • MRI – 2 cm pituitary mass
  • Dx: Secondary (pituitary) hypothyroidism from prolactinoma
indications for ordering a ft4 when you have a normal tsh
Indications for ordering a FT4 when you have a “normal” TSH
  • Clinical manifestations of hypothyroidism but a low normal TSH and suspected pituitary disease (secondary hypothyroidism)
  • Known secondary hypothyroidism, to follow response to levothyroxine treatment
    • Eg – In panhypopitutarism TSH often low regardless of treatment, FT4 needs to be checked to eval levothyroxine dose
  • On a drug that known to affect TSH secretion
    • Dopamine agonist/antagonists, amiodarone, glucocorticoids
case study 3
Case study #3
  • A 43 YO woman with PMH significant for hyperthyroidism s/p radioactive iodine ablation 6 years ago (now hypothyroid), anxiety, hypertension, polysubstance abuse comes in for followup.
  • Over the past few years her levothyroxine has been increased because of TFT abnormalities, and is now 250 mcg/day. She states she is taking her medications religiously
her labs
Her labs….

How would you manage her levothyroxine dose?

causes of levothyroxine resistance
Causes of “levothyroxine resistance”
  • **Nonadherance**
    • Clues 
      • Normal FT4 but elevated TSH (playing “catch up” by taking T4 1 week prior to lab test)
      • Widely fluctuating TSH levels
  • Conditions that induce hypochlorohydria
    • Thyroxine requirement 22-33% higher in those with H Pylori, atrophic gastritits, celiac sprue
  • Medications that affect absorption
    • Iron, Calcium, PPI, H2 blocker, aluminum containing anacids
slide17

Drugs Potentially Altering Thyroid Hormone Replacement Requirements

  • Increase replacement requirements
  • Drugs that reduce thyroid hormone production
    • Lithium
  • Iodine-containing medications
    • Amiodarone (Cordarone)
  • Drugs that reduce thyroid hormone absorption
    • Sucralfate (Carafate)
    • Ferrous sulfate (Slow Fe)
    • Cholestyramine (Questran)
    • PPI, H2 blockers
    • Aluminum-containing antacids
    • Calcium products
  • Drugs that increase metabolism of thyroxine
    • Rifampin (Rifadin)
    • Phenobarbital
    • Carbamazepine (Tegretol)
    • Warfarin (Coumadin)
    • Oral hypoglycemic agents
  • Increase thyroxine availability and may decrease replacement requirements (displace thyroid hormone from protein binding)
    • Furosemide (Lasix)
    • Salicylates
another case
Another case…
  • A 34 YO woman comes into clinic with anxiety, palpitations and heat intolerance for 5 months.
  • PE HR 120, Reg. Mild tremor, mild exopthalmos, mild enlarged thyroid, no nodules
  • TSH < 0.01
  • FT4 1.60 (0.58-1.65)
  • What do you do next?
slide19

Scheme for Investigating Cases of Suspected Hyperthyroidism

(TSH)

(FT4)

(FT3)

*If you suspect hyperthyroid but FT4 normal, check FT3!

back to our patient
Back to our patient…
  • A 34 YO woman comes into clinic with anxiety, palpitations and heat intolerance for 5 months.
  • PE HR 120, Reg. Mild tremor, mild exopthalmos, mild enlarged thyroid, no nodules
  • TSH < 0.01
  • FT4 1.60 (0.58-1.65) FT3 5.8 (2.3-4.2)
    • (“T3 thyrotoxicosis”)
  • What is the cause of her hyperthyroidism?
common causes of hyperthyroidism 98
Common causes of hyperthyroidism (98%)
  • Increased hormone synthesis
    • Graves disease
    • Multinodular goiter / Toxic adenoma
  • Decreased hormone synthesis
    • Thyroiditis
    • Iatrogenic (taking too much levothyroxine)
    • Medication (amiodarone)
hyperthyroidism secondary to increased hormone synthesis
Hyperthyroidism secondary to increased hormone synthesis
  • Graves disease
    • Caused by thyroid-stimulating antibodies
    • Most common cause of hyperthyroidism
    • Manifested by exopthalmos, pretibial myxedema, smooth enlarged thyroid
  • Toxic Multinodular Goiter / Toxic adenoma
    • Caused by nodule(s) functioning independent of feedback mechanism
    • Approx 10% of hyperthyroidism
  • (Rare stuff – Iodine load, TSH producing adenomas, trophoblastic disease)
hyperthyroidism secondary to decreased hormone synthesis
Hyperthyroidism secondary to decreased hormone synthesis
  • Thyroiditis (inflammation of thyroid gland with subsequent release T3/T4)
    • Subacute (DeQuevain’s) – URI sx with fever, malaise and tender goiter
    • Silent – No real sx
    • Postpartum – Often self-limiited
    • Med induced (amiodarone)
  • Exogenous administration
  • (Rare stuff – Struma ovarii, metastatic follicular thyroid CA)
back to our patient1
Back to our patient…
  • A 34 YO woman comes into clinic with anxiety, palpitations and heat intolerance for 5 months.
  • PE HR 120, Reg. Mild tremor, mild exopthalmos, mild enlarged thyroid, no nodules
  • TSH < 0.01
  • FT4 1.60 (0.58-1.65) FT3 5.8 (2.3-4.2)
    • (“T3 thyrotoxicosis”)
  • Does she need a thyroid scan (Iodine 123 thyroid uptake scan)?
common indications for a thyroid uptake scan
Common indications for a thyroid uptake scan
  • To differentiate between hyperthyroidism from increased vs decreased hormone synthesis
    • “URI sx, tender thyroid  is this thyroiditis?”
  • Pre radioactive ablation to determine dose
  • Results can suggest etiology:
    • Graves: Diffuse increased uptake
    • Toxic goiter/adenoma: Focal area(s) increased uptake
    • Thyroiditis/Iatrogenic: Reduced uptake
treatment of hyperthyroidism
Treatment of hyperthyroidism
  • Graves disease:
    • Spontaneous remission in 30-50%, antithyroid drugs or iodine ablation acceptable (+ beta blocker)
  • Toxic multinodular goiter:
    • Remission rare, usually treat with iodine ablation (+ beta blocker)
  • Thyroiditis:
    • Treat symptoms with beta blocker +/- NSAIDS, watch closely for hypothyroidism
beta blockers in hyperthyroidism
Beta blockers in hyperthyroidism
  • Used to reduce tachycardia, tremor, other sx
  • Selective vs nonselective?
    • Probably doesn’t matter
  • Reasonable to start
    • Atenolol 50-100 daily
    • Toprol XL 100 daily
antithyroid medications
Antithyroid Medications
  • Methimazole (tapazole) – Preferred agent
    • Long half life – once daily dosing
    • Reduced incidence side effects
    • Usually start 20 daily, increased for severe thyrotoxicosis
  • PTU
    • Preferred agent in pregancy (theoretically dosen’t cross placenta)
    • Used in thyrotoxic storm (prevents conversion T4T3)
antithyroid medications and side effects
Antithyroid Medications and side effects
  • Agranulocytosis
    • Usually occurs in first 3 months of therapy
    • Councel every patient: “If you have sore throat & fever, stop med and go to ER”
  • Hepatitis (rare)
  • Rash
should i order thyroid antibodies
Should I order Thyroid Antibodies??
  • Antithyroid Peroxidase (Anti-TPO)
    • Present in 13% general population
    • Consider ordering in subclinical hypothyroidism when deciding whether to tx (high levels correlate with progression to overt hypothyroidism)
  • Antithyroglobulin (Anti-Tg)
    • Measure in all patients with differentiated thyroid cancer (guides therapy)
  • Anti-TSH receptor Ab
    • Usually elevated (with anti-TPO) in setting of Graves disease
    • Only order if Graves dx is in question
subclinical hypo thyroidism
Subclinical Hypothyroidism
  • Defined by elevated TSH with nl FT4
  • No clear guidelines for how to tx
  • Suggested approaches:
    • Treat all with hypothyroid symptoms
    • Treat all with TSH > 10
    • Check anti-TPO ab, if +  consider tx (high chance pt will develop overt hypothyroid)
subclinical hyper thyroidism
Subclinical Hyperthyroidism
  • Defined by supressed TSH with normal FT3/FT4
  • Again, no clear guidelines how to tx
  • Risk of not treating most risky in elderly patients and/or those with cardiac or bone comorbidities
    • Osteoporosis
    • Atrial Fibrillation
    • Cardiovascular disease
subclinical hyper thyroidism treatment
Subclinical Hyperthyroidism –Treatment
  • A Suggested approach:
    • If TSH < 0.1, consider tx (esp in elderly)
    • If TSH 0.1-0.5, may follow patient, but consider treatment if:
      • Unexplained weight loss
      • Osteoporosis
      • Atrial Fibrillation
      • Cardiovascular disease
      • Thyroid scan shows area of high uptake
main points
Main Points
  • Starting dose of levothyroxine depends on patient’s age and elevation of TSH
  • If hypothyroid sx but low/normal TSH, get FT4 (evaluate 2ndary hypothyroid)
  • If supressed TSH but normal FT4, get FT3 (evaluate T3 thyrotoxicosis)
  • “Levothyroixine resistance” usually from noncompliance, but consider hypochlorhydria and medications as etiology
main points continued
Main points, continued
  • Graves disease can be treated with medications or iodine ablation
  • Methimazole is the antithyroid medication of choice, but watch for agranulocytosis
  • There are few indications for ordering thyroid antibodies
  • Treatment of subclinical hyper and hypothyroidism controversial
ad