10/9- Case Conference 2: Thyroid Flashcards

1
Q

Case 1)

  • A 38-year-old woman has been complaining of weight loss despite increased appetite, heat intolerance, sweating, severe anxiety and oligomenorrhea.
  • She also has palpitations and increased frequency of bowel movements.
  • She recalls that her mother and maternal aunt may have had thyroid problems.
  • She delivered a full-term normal baby 6 months ago

What are the possible endocrine causes of these symptoms?

A

DDx:

  • Hyperthryoid
  • Graves/Toxic Nodular
  • Thyroiditis
  • TSH-oma
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2
Q
  • The physical examination reveals a very anxious woman with persistent crying spells, tremor of the extremities, and warm, moist, silky skin.
  • The pulse is 124 and regular, the blood pressure 145/80.
  • The thyroid gland is diffusely enlarged to three times the normal size and non-tender.

How do these physical findings help in narrowing the differential diagnosis?

A

?

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3
Q
  • The TSH is under 0.01 uIU/mL (0.35 to 5.5 uIU/mL)
  • The Free T4 is 4.2 ng/dL ( 0.89 to 1.76 ng/dL)

What is your interpretation of these results, and what would you do next? What labs do you want?

A
  • Low TSH rules out TSH-oma
  • Elevated T4 points toward problem in thyroid (primary hyperthyroidism); could be Grave’s or thyroiditis
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4
Q

How to distinguish Graves vs. thyroiditis?

A

Differentiate via iodine uptake scan

  • Graves: operproduction of thyroid hormone
  • Thyroiditis: thyroid being destroyed and releasing hormone

Thyroid gland takes up iodine

  • If overproducing, iodine uptake will be high (Graves)
  • If not overproducing, iodine uptake will be low (Thyroiditis)
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5
Q

How to treat Grave’s Disease?

A

RAI (radioactive iodine) ablation: most in the US

  • Push from hyperthyroidism -> hypothyroid state (easier to treat long term)

Antithyroid drugs: more in Europe

  • PTU
  • Methimazole (MMI)
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6
Q

How to treat silent (post-partum) thyroiditis?

A

Typically self-limiting

  • No treatment if asymptomatic

If symptomatic:

  • Beta blockers for symptoms
  • Treat pain
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7
Q

Case 2)

  • A 28-year-old woman comes to you for a “routine physical”
  • She informs you that when she was 5 years old she was told that she had an enlarged thyroid gland. She comes from a country with known areas of iodine deficiency. She has lived in Houston for 10 years.
  • On review of systems, she admits to tiredness, weight gain, and menstrual periods which are often irregular, usually of long duration (7-8 days of bleeding). She has not been able to conceive despite unprotected intercourse.
  • Her mother and aunt had a history of thyroid problems in her home country.

What thyroid conditions would you consider, and how are they related to her past and family histories?

A

Significant history:

  • Goiter
  • Infertility

DDx: hypothyroidism

  • Endemic iodine deficiency (but living in Houston long enough that you wouldn’t expect this)
  • Family history points to autoimmune (maybe Hashimoto’s)
  • Hypogonadism (because of fertility issues)
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8
Q
  • The physical examination shows a small but firm, rubbery thyroid gland without palpable nodules
  • The skin is dry and cold. The pulse is 68/min and regular, blood pressure 100/78 mm Hg. Deep tendon reflexes show a slow relaxation phase.

What are the differential diagnoses?

A
  • These findings confirm hypothyroidism expected from history
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9
Q

How could you distinguish between primary and secondary disease (problems with thyroid vs. pituitary)?

  • The TSH is 24 uIU/mL(0.35 to 5.5 uIU/mL)
  • The Free T4 is 0.3 ng/dL ( 0.89 to 1.76 ng/dL)

What is your interpretation, and what would you do next to determine the etiology?

A

Distinguish with TSH/results

  • Primary hyperthyroidism (thyroid problem) if high TSH yet low FT4
  • Could look for TPO Abs for Hashimoto’s
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10
Q

The patient states that one of her most pressing concerns is to become pregnant.

What can you tell her regarding fertility and the course of pregnancy in this condition?

A

Hypothyroidism is associated with fertility issues…. (?)

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11
Q

Case 3)

  • A 56-year-old woman, with no family history of thyroid disease, suddenly discovers a swelling in the neck. She comes to you for evaluation.
  • She gives you a history of X-ray treatments for an enlarged thymus when she was a baby. She is anxious and nervous.

What are the possibilities, and how does the history help to narrow them?

A
  • Neck radiation increases risk of thyroid nodules, thyroid cancer (2-3x)
  • Mass could be many things: thyrosglossal duct cyst, hematoma, carotid body tumor… a lot
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12
Q

The physical examination reveals a solitary nodule in the left lower pole of the thyroid, about 2 x 3 cm in size, and of firm consistency

Now what are the possibilities?

What would you like to know?

How would you proceed further?

A

DDx:

  • Left lower lobe thyroid nodule

Want to (how to evaluate a thyroid nodule):

1. TSH panel (thryoid function tests)

  • If normal/low TSH, do FNA (may precede with US)
  • If undetectable TSH (under 0.01), do RAIU scan
  • Could have subclinical hypothyroidism (normal FT4)
  • Want to see if nodule is hot (no biopsy needed) or cold
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13
Q

Case 4)

  • ​A 29-year-old woman complains of occasional palpitations, weight loss of 10 lbs, and anxiety for 1 month
  • She describes having a very sore throat and neck last month with an upper respiratory tract infection.
  • She has not been pregnant before.

With this history, what is your differential diagnosis?

A

Symptoms indicate hyperthyroidism

DDx:

  • Subacute thryoiditis
  • Typically in females
  • Post-viral infection
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14
Q

The free T4 is 2.1 ng/dl (normal is 0.89-1.76 ng/dl) and TSH is < 0.01 uIU/mL(0.35 to 5.5 uIU/mL).

What is your interpretation and what is your next step

A

Interpreation is that this is subacute thyroiditis

(High T4 with undetectably low TSH)

  • Could confirm by demonstrating low uptake on iodine scan
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15
Q

When do you see high vs. low uptake of iodine?

A

High uptake with increased production

  • Grave’s disease
  • Toxic nodules
  • Pituitary adenoma (causing thyroid to overproduce)

Low uptake with other issues

  • Thyroiditis
  • Thyrotoxicosis??
  • Exogenous thryoid hormone
  • Ectopic thyroid production
  • High dietary iodine or contrast
  • Malignancy (although, may not look for uptake because TSH could be normal/low; typically do uptake tests when hyperthryoid)
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