Endocrinology Week 1 Summary

Question 1

A 24 year-old woman, Maria Aquino, presents with two-month history of weight loss, anxiety, hyperdefecation, scant menses, palpitations and hear intolerance.  On exam, she appears anxious.

Aquino has: HR 126, BP 140/68, a fine tremor, very brisk reflexes, mildly enlarged thyroid (30 g), sTSH <0.01, free T4 46 (N 7.5-16), free T3 12 (N 3.5-6)

What are the two most likely diagnoses in your differential? How do you differentiate them?

  • Graves’ disease
  • Subacute thyroiditis
  • More on history:
    • other autoimmune diseases
    • positive family history of Graves’
    • orbitopathy or pretibial myxedema
    • history of preceding URTI or pregnancy
    • painful/tender thyroid
  • RAI uptake (if not pregnant, not on thiouracils, no iodine ingestion recently)
    • elevated with Graves’ disease
    • multinodular goiter
    • toxic adenoma
    • molar pregnancy/choriocarcinoma
    • low with subacute thyroiditis, exogenous thyroid (medication or thyroid gland ingestion), struma ovarii
  • TSI (thyroid stimulating immunoglobulin)
    • takes a while to get back
  • ESR is elevated in subacute thyroiditis

Question 2

Ms. Rodrigues, a 35 year-old woman, was recently given radioactive iodine for Graves’ disease, one month ago.  She is now complaining of extreme fatigue, needing an extra sweater in the middle of summer, and constipation. She weighs 60 kg, with HR 54, BP 120/95, hoarse voice, and delayed biceps reflex relaxation. sTSH>100.

Write a prescription for her, and counsel her on taking the new medication. 

Weight (kg) * 1.6
= 60 * 1.6 = 96 mcg
Therefore, take Levothyroxine 0.1 mg po daily.

Take with water on an empty stomach, no food for 30-60 minutes afterwards, take vitamins/iron/calcium at another meal.

How would you determine if this was a correct dose? 

Check her sTSH 6 weeks later (half-life of T4 is 1 week, this will be just over  5.5 half-lives, at steady state).

What would you prescribe for her if she were 70 years old, or had angina?

Levo-thyroxine 0.025 mg po daily (increased by 0.025 mg daily every 4-6  weeks until sTSH is normal)

Question 3

A 40 year-old man, Ron McNab, has a 3 cm soft, non-fixed thyroid nodule found on routine physical examination. No lymph nodes are palpable. He has no local symptoms, including no hoarseness.

What two questions should be asked on history to see if he has an increased risk of malignancy?

Family history of thyroid cancer.
Personal history of radiation exposure.

What is his risk of malignancy in the nodule if the answer to the above questions is “no”?


What is the likeliest diagnosis?

Colloid nodule.

How would you investigate him?

Check his sTSH. If it is normal or elevated, he needs a thyroid ultrasound and a fine needle biopsy of the nodule.

If the TSH is suppressed, he needs a thyroid scan.

If the nodule is cold, it should be biopsied; if hot, he should be treated for a hot nodule (no biopsy needed).

Question 4

List 4 causes for each of primary and secondary hypertriglyceridemia.

Primary hypertriglyceridemia:

  • Familial hypertriglyceridemia
  • Familial combined hyperlipidemia
  • Familial dysbeta-lipoproteinemia
  • ApoC2 deficiency
  • Lipoprotein lipase deficiency

Secondary hypertriglyceridemia/hyperlipidemia:

  • Diabetes, metabolic syndrome, obesity
  • Cushing’s disease, acromegaly
  • Chronic renal disease
  • Parenchymal liver disease
  • EtOH
  • Therapy with:
    • Estrogen
    • Accutane
    • Protease inhibitors
    • Atypical antipsychotics

Question 5

A 40 year-old man, Maurice LeBlanc, has his lipids checked for the first time. He has no significant past medical history, but a positive family history of early CAD.

LDL-cholesterol 6.8 mmol/L
Total cholesterol 8.8 mmol/L
Triglycerides 1.1 mmol/L
HDL-cholesterol 1.5 mmol/L

What is the lipid abnormality?

Elevated LDL cholesterol.

List three physical (non-vascular) signs that should be looked for.

  • Arcus (circus) cornealis
  • Xanthelasmata
  • Tendinous xanthomata

(NOT eruptive xanthoma, nor lipemia retinalis which are seen with high triglycerides)

List 3 potential primary causes and 3 secondary causes for this lipid abnormality.


  • Polygenic hypercholesterolemia
  • Familial hypercholesterolemia
  • Familial combined hyperlipidemia


  • Hypothyroidism
  • Biliary cirrhosis
  • Nephrotic syndrome
  • Anorexia nervosa
  • Drugs:
    • carbamazepine
    • cyclosporine

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