10/9- Case Conference 2: Thyroid Flashcards
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?
DDx:
- Hyperthryoid
- Graves/Toxic Nodular
- Thyroiditis
- TSH-oma
- 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?
?
- 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?
- Low TSH rules out TSH-oma
- Elevated T4 points toward problem in thyroid (primary hyperthyroidism); could be Grave’s or thyroiditis
How to distinguish Graves vs. thyroiditis?
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)
How to treat Grave’s Disease?
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)
How to treat silent (post-partum) thyroiditis?
Typically self-limiting
- No treatment if asymptomatic
If symptomatic:
- Beta blockers for symptoms
- Treat pain
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?
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)
- 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?
- These findings confirm hypothyroidism expected from history
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?
Distinguish with TSH/results
- Primary hyperthyroidism (thyroid problem) if high TSH yet low FT4
- Could look for TPO Abs for Hashimoto’s
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?
Hypothyroidism is associated with fertility issues…. (?)
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?
- 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
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?
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
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?
Symptoms indicate hyperthyroidism
DDx:
- Subacute thryoiditis
- Typically in females
- Post-viral infection
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
Interpreation is that this is subacute thyroiditis
(High T4 with undetectably low TSH)
- Could confirm by demonstrating low uptake on iodine scan
When do you see high vs. low uptake of iodine?
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)
