Transcript Approach to Thyroid Disorders

APPROACH TO THYROID
DISORDERS
YOU THINK YOU KNOW…
BUT JUST YOU WAIT.
DR SHAUNA BASSEL, RESIDENT PHYSICIAN
JUNE 2016
Beyonce
 Your patient is a 26F presenting with a 6-month hx
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of fatigue, weakness, difficulty concentrating
She notes that she has gained ~6 kgs despite same
meal plan, though less exercise
Known for long-standing constipation
She has decided to present to you now because she
hasn’t had menstruation x 2 mths and has started
noticing hair thinning/clumps in showers
FMHx: Maternal: Vitiligo; Paternal: ?Vitamin
deficiency anemia
Hypothyroid!
 General: Fatigue, cold intolerance, hoarseness, macroglossia
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(associated sleep apnea)
CVS/Resp: Bradycardia, hypoTN, worsening CHF/Angina,
DLPD, decreased exercise capacity, resp muscle weakness
(hypoventilation)
GI/GU: Weight gain despite poor appetite, constipation,
menstrual changes (menorrhagia, amenorrhea, impotence)
Neuro: Paresthesias, muscle cramps, DTR ‘hung’, seizures
Derm: Periorbital edema, dry/rough skin, coarse hair with
thinning
Heme: 10% associated with pernicious anemia (related to
auto-immune thyroiditis)
Tell me more…
 F>M
 Most common cause worldwide is I- deficiency; in
Western World most common Hashimoto’s
(primary)
 1° (thyroid), 2° (pituitary), 3° (hypothal), 4° (tissues)
 Treatment: L-thyroxine; monitor by TSH
 If 2° or 3°, monitor by free T4 as TSH unreliable
Hashimoto’s Thyroiditis
 Most common 1° hypoT4 in N. America; F>M
 Chronic auto-immune, Ab against thyroid
components
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Thyroglobulin, Thyroid Peroxidase, TSH receptor, Na/I
symporter
 High TSH, low T4/T3; Anti-TPO and TG Ab in
serum
 Treat with L-Thyroxine (Synthroid = T4 analog)
Uh Oh…Myxedema Coma
 Severe hypothyroidism (rare; up to 60% mortality)
 Complicated by trauma, sepsis, cold exposure, MI, narcotics/hyponotics,
stress response
 Decreased mental status and hypothermia, hyponatremia,
hypoTN, hypoglycemia, bradycardia, hypoventilation,
generalized non-pitting edema, ‘myxedema madness’
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Check ACTH, cortisol to r/o adrenal insufficiency
 Treatment:
 Administer T3: 5-20mcg IV, followed by 2.5-10mcg q8h – continue until
clinical improvement
 Administer T4: 200-400mcg IV, then 50-100mcg IV daily (until po)
 Stress-dose corticosteroids
 Supportive measures: ICU, mechanical ventilation, rewarming, IVF with
electrolyte replacement, glucose, treatment of underlying etiology
Lady Gaga
 32F presenting with 5-month history of restlessness,
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anxiety and weight loss
She is an avid runner and is now unable to run outside as
she overheats easily and cannot tolerate the summer
weather
She recently started noticing her hands shaking, and she
feels quite weak
She has also been experiencing changes in bowel habits,
with waxing/waning diarrhea
She and her husband have been trying to get pregnant x1
year without success; she describes a prolonged hx of
irregular menses
Hyperthyroid!
 General: Fatigue, heat intolerance, irritability, fine
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tremor
CVS/Resp: Tachycardia, A-fib, palpitations
GI/GU: Weight loss with increased appetite,
hyperdefecation,
oligomenorrhea/amenorrhea/decreased fertility
Skin: Fine hair, moist skin, soft nails, palmar erythema
MSK: Proximal muscle weakness, decreased bone mass
Heme: Splenomegaly, LAD, lymphocytosis, leukopenia
Optho: Lid lag, retraction, proptosis, diplopia,
conjunctival injection
Tell me more…
 F>M (1% gen. population)
Grave’s Disease
 Most common cause of thyrotoxicosis (peak 3-4th
decade)
 Auto-immune disorder: Auto-Ab to TSH receptor
(stimulation indep. of TSH)
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Immune response triggered by: postpartum, I- excess, lithium,
viral/bacterial infections, steroid withdrawal
 Optho changes: 2° to glycosaminoglycan deposition –
inflammation and increased osmotic pressure in orbit
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Deposition in skin causes pretibial myxedema and thickening of
distal phalanges
 Low TSH, Increased thyroid hormone, Increased RAIU
(homogenous)
Grave’s
Thyrotoxicosis Treatment
 1) Thionamides
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Inhibit thyroid hormone synthesis; PTU inhibits peripheral T4 – T3
conversion
6-18 mths treatment
SE: Agranulocytosis, Hepatitis, Fever/Arthralgia
 2) Symptomatic: Beta-blockers
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Smoking cessation and high-dose pred may help with optho features
 3) I-131 Radioablation
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High incidence of post-ablative HypoT4
Contraindicated in pregnancy
 4) Subtotal or Total Thyroidectomy
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Risk of hypoPTH and vocal cord palsy
 Lifetime follow-up due to increased risk of relapse
Uh Oh….Thyroid Storm
 Severe hyperthyroidism (rare, mortality 20-30%)
 Often precipitated by acute event: trauma, surgery, infection,
acute I- load, parturition
 Tachycardia, hypoTN, arrhythmia (A-fib),
hyperpyrexia, agitation, hyperglycemia,
hypercalcemia, anxiety & delirium/psychosis – may
progress to stupor/coma
 Dx based on clinical presentation and biochemical
evidence of hyperT4:
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TSH assessed in all pts; if low, investigate T3/T4
Treatment of Thyroid Storm
 Beta-blocker (Propranolol 60-80mg po q4-6h)
 PTU 200mg q4h or Methimazole 20mg q4-6h
 Iodine or Lugol’s solution: administration delayed one
hour post-thionamide
 Stress-dose glucocorticoids
 Cholestyramine 4g
 Supportive measures: ICU, treat underlying etiology,
IVF, diuresis (if CHF)
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*Be wary of ASA use: can increase serum T4 and T3
 Little published data on efficacy of RadioI in thyroid
storm
Approach to Enlarged Thyroid
 On P/E – palpate homogenously-enlarged thyroid vs.
nodule/nodular goitre
 First step: TSH
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If low, proceed to thyroid scan
If normal/high, proceed to thyroid U/S with FNA
 Next step: Thyroid Scan
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Technetium-99: tests structure – differentiates between hot
(functioning) and cold
*Radioactive Iodine Uptake (RAIU): tests function – if thyrotoxic
and want to determine source
 Next step: Thyroid U/S with FNA
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Indications about thyroid size, anatomy, structures in neck,
lymphatic involvement
FNA for cytology (best with US guidance)
When investigating a nodule…
 Patient history:
 Familial history of endocrine disorders (MEN)
MEN 2A: Medullary Thyroid Cancer, Pheo, Parathyroid tumours
 MEN 2B: Medullary Thyroid Cancer, Pheo, Benign neuromas
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FamHx thyroid cancer, other cancers: Gardner’s, FAP
Personal radiation history (head/neck)
 Benign thyroid conditions (ex: Hashimoto’s, Grave’s)
increase risk of cancer
 Symptoms of compression – hoarseness, SOB,
dysphagia