[PATH] Thyroid and Parathyroid Disorders

Question 1

If serum values of Ca²⁺ and PO4 are moving in the same direction (i.e., both ↓) this tell you that the problem is related to what?

Answer 1

Vitamin D

Question 2

If calcium is high, but PTH is low, what are some of the underlying causes you need to investigate?

Answer 2

• Malignancy + Metastasis + Lymphoma
• Granulomatous disease
• Drugs
• Multiple myeloma
• Vit D intoxication

Question 3

Polyuria + dehydration + renal impairment are associated with (chronic or acute) development of hypercalcemia?

Answer 3

Acute

Question 4

Which medication should be used in a patient with chronic hypercalcemia who has developed HTN?

Answer 4

Loop diuretics —> ↓ serum [Ca²⁺] and ↓ BP

Question 5

If you suspect a vitamin D deficiency in a patient with ↓ Ca²⁺ and ↓ PO4, which form of vitamin D should you order a test for, why?

Answer 5

• 25-OH Vitamin D = the storage form; important to check how depleted the pt is
• 1,25-OH Vit D the active form should also be checked

Question 6

What’s the formula for corrected calcium when albumin is low?

Answer 6

Ca_corrected= measured Ca²⁺ + 0.8 (4.0 - serum albumin)

Question 7

What would you expect the serum and urine calcium levels to be like in someone who is bed ridden and has normal kidney function?

Answer 7

• Serum levels will likely be normal
• Urine levels will be elevated = hypercalciuria
• Due to ↑ osteoclast activity causing ↑ Ca²⁺ in blood and suppression of PTH from the high Ca²⁺ –> normal renal function maintains homeostasis

Question 8

What is responsible for the hydroxylation of 25-OH vitamin D to 1,25-OH vitamin D?

Answer 8

PTH

Question 9

What is a peripheral vs. central DEXA scan used for?

Answer 9

• Central: used for larger bones like the spine or hips
• Peripheral: used for screening ONLY: wrist, heel, leg, fingers

Question 10

Which “T score” on a DEXA scan is considered indicative of osteoporosis?

Answer 10

T score < -2.5

Question 11

What is the recommended type of calcium supplement for replacing the calcium in someone with hypocalcemia/osteoporosis; what if they have low stomach acid?

Answer 11

• Calcium Carbonate (recommended)
• Calcium citrate if LOW stomach acid

Question 12

What EKG finding is indicative of hypercalcemia vs. hypocalcemia?

Answer 12

• Hypercalcemia = shortened QT interval –> reflects accelerated repolarization
• Hypocalcemia = prolonged QT interval

Question 13

What are the actions of 1,25-OH-vit D on the bone, kidney, and gut?

Answer 13

• Bone = ↑ Ca²⁺ resorption; stimulate osteoclasts
• Kidney = ↑ Ca²⁺ and PO4 reabsorption
• Gut = ↑ Ca²⁺ and PO4 absorption

Question 14

↑ TSH and ↑ T4 would be indicative of what underlying condition?

Answer 14

TSH producing tumor

Question 15

What are 2 opthalmic findings assoc. w/ hyperthyroidism?

Answer 15

• Lid lag
• Exophthalmos

Question 16

What is often the only thing needed for the diagnosis of Graves disease?

Answer 16

History and PE

Question 17

Which lab tests can be useful in supporting diagnosis of Graves disease, but are not needed?

Answer 17

• TSH level (will be suppressed)
• Thyroid scan will show unique homogenous uptake of ¹³¹I
• TSI antibody, unique to Graves, but not needed for diagnosis

Question 18

What will a thyroid scan of someone with Graves show?

Answer 18

Homogenous DIFFUSE ↑ uptake

Question 19

What are 3 pitfalls to using a thyroid scan for Graves diagnosis?

Answer 19

• Time consuming and expensive
• The isotopecosts more (iodine)
• Scanning at 6 hours and at 24 hours

Question 20

Which medication is of utmost importance in controlling the cardiovascular and neurological sx’s of Graves?

Answer 20

Beta blockers –> specifically non-selective beta-blockers

Question 21

If a patient cannot tolerate a beta-blocker, due to asthma, what else can be given for Graves disease?

Answer 21

Trial of CCB

Question 22

When evaluating a thyroid nodule found on exam, which test is critical to the work up, why?

Answer 22

TSH level –> critical to know if nodule or gland is hyperfunctioning

Question 23

If someone with a thyroid nodule has low TSH, what is the next step in diagnosing the patient?

Answer 23

• Thyroid scan
• Something is suppressing the TSH

Question 24

If someone with a thyroid nodule has normal TSH, what is the next step in diagnosis?

Answer 24

• Fine needle aspiration (FNA)
• If TSH is not suppressed, have to see what the nodule is doing; may be cold…. not producing thyroid hormone

Question 25

Answer 25

B. Toxic nodule

Question 26

What are some structures in the neck that you should be worried about a benign thyroid nodule potentially damaging?

Answer 26

- **Recurrent laryngeal N.** - **Parathyroid glands**

Question 27

What are 5 pieces of information which are helpful in predicting that a thyroid nodule is benign?

Answer 27

- **Family hx** of benign nodules - **Hashimoto's** - **TENDERNESS** - **Mobile nodule** - **Concomitant diagnosis** of **hypo-** or **hyperthyroidism**

Question 28

What are 6 factors which help predict a thyroid nodule may be malignant?

Answer 28

- **Very young** pt - **Very old** pt - **MEN** - **Hx** of **neck irradiation** - **FIRM**, **FIXED** nodules - **Lymphadenopathy**

Question 29

Why are we more worried about "cold" thyroid nodules?

Answer 29

- Represent **85%** of all thyroid nodules - **85%** of them are **benign**, BUT **15%** are malignant

Question 30

If a FNA comes back showing a thyroid nodule is benign, what is the next best step in treatment?

Answer 30

- **Monitor** by **US** - **Surgery** if **further growth** or **suspicious cytology**

Question 31

What are the classic findings of TSH and T4 in a patient with pituitary adenoma as source of hyperthyroidism?

Answer 31

- **Very high TSH** - **High** to **very high T4**

Question 32

What is your working diagnosis based off the labs?

Answer 32

**Hypothyroid - Hashimoto burn out**

Question 33

What would the seurm levels of TSH, T4, and T3 be like in patient with hypothyroidism due to pituitary failure?

Answer 33

Question 34

Loss of lateral aspects of eyebrows (Queen Anne Sign) is a finding associated with what endocrine abnormality?

Answer 34

**HYPOthyroidism**

Question 35

What cardiovascular findings are typical of hypothyroidism?

Answer 35

- **Bradycardia** - ↓ **systolic pressure** - ↓ or ↑ **diastolic pressure** - **Non-pitting edema (myxedema**) - **Pitting edema** may be seen

Question 36

What is the most useful lab test in diagnosis hypothyroidism and should be the first test ordered to assess thyroid function?

Answer 36

**TSH**

Question 37

Which cause of hypothyroidism could be misleading based on TSH levels?

Answer 37

**Pituitary dysfunction** --\> ↓ TSH (usually would expect ↑ TSH)

Question 38

With the availability of free T4, why should the measure of total T4 (or total T3) be avoided?

Answer 38

**Total T4** and **T3** is affected by the **binding proteins**

Question 39

Which serum antibody is the most helpful in making the diagnosis of autoimmune hypothyroidism?

Answer 39

**Anti-TPO**

Question 40

Thyroid stimulating immunoglobulins (TSI) levels can be useful in the diagnosis of what?

Answer 40

Graves

Question 41

What is the most important aspect of assessment when using thryoid replacement therapy?

Answer 41

**- Clinical observation** of the sx's is most important - Watch for **over treatment** - Development of **sub-clinical** or **overt HYPERthyroidism**