Endocrine quiz answers

Here are the answers and explanations to yesterday’s endocrine quiz questions.

1. Which of the following is true of papillary thyroid carcinoma?

A. May have psammoma bodies
B. The least common kind of thyroid carcinoma
C. The type of thyroid carcinoma with the worst prognosis
D. Occurs in patients with MEN II
E. Most common in elderly patients

The answer is A (check out the cool photo of the psammoma body, above). Psammoma bodies are common in papillary carcinoma (of all types, by the way, not just papillary carcinoma of the thyroid). If you can remember that papillary carcinoma is often called the Little Orphan Annie tumor, then you’ll remember most of the important facts about it. Papillary carcinoma is the most common kind of thyroid carcinoma (so B is wrong) and also the kind with the best prognosis (so C is wrong). Patients with MEN II get medullary, not papillary, thyroid carcinoma (so D is wrong). Papillary carcinoma is more common in young women (so E is wrong). Psammoma bodies are common in papillary carcinoma, so A is correct.

 


2. The most common cause of hypothyroidism in underprivileged countries is:

A. Pituitary dysfunction
B. DeQuervain’s thyroiditis
C. Graves’ disease
D. Hashimoto’s thyroiditis
E. Iodine deficiency

The answer is E, iodine deficiency. To give you an idea of the devastating effects of the disease, here is a short story about how hypothyroidism affected one child’s life. Congenital hypothyroidism is the biggest cause of preventable mental retardation in the world, and it is most prevalent in disadvantaged areas of the world. In most cases, it is simply due to a lack of iodine in the diet. Unicef is working to eliminate iodine deficiency in all parts of the world. Iodine is cheap; even a small donation will make a big difference in many children’s lives.

 


3. Which of the following hormones, in addition to participating in the initiation of labor, may play a role in trust, monogamy, and the desire to cuddle?

A. Cortisol
B. Thyroid hormone
C. Parathormone
D. Oxytocin
E. Antidiuretic hormone

The answer is D, oxytocin. Oxytocin is one crazy hormone. It’s been shown to be involved in everything from snuggling to monogamy to trust. It can even help you do better on tests! If you feel your levels need a little boost, or if you want more trust or cuddling (or monogamy?) in your life, you can actually buy oxytocin in spray form.

 


4. A patient with Cushing syndrome might present with any of the following EXCEPT:

A. Obesity
B. A buffalo hump
C. Moon facies
D. Bronze or hyperpigmented skin
E. Glucose intolerance

All the answers except D are commonly seen in Cushing syndrome. Bronze or hyperpigmented skin is a finding seen in Addison Disease. It occurs because the pituitary is cranking out ACTH like crazy in an effort to get the adrenals to make their hormones. ACTH comes from a bigger precursor called pro-opiomelanocortin (POMC) which also gives rise to melanocyte-stimulating hormone (MSH). If you’re making more ACTH, you’re also by necessity making more MSH – and your skin will turn bronze.

 


5. Patients with diabetes have an increased risk of all of the following EXCEPT:

A. Cataracts
B. Infections
C. Increased atherosclerosis
D. Peripheral neuropathy
E. Pancreatic carcinoma

The big things with diabetes are infections, vascular problems, eye problems, and nerve problems. Pancreatic carcinoma doesn’t show any significant increased incidence in patients with diabetes.

 


6. Which of the following is true regarding multiple endocrine neoplasia (MEN) I syndrome?

A. Virtually all patients develop medullary thyroid carcinoma
B. The genetic abnormality involves the RET gene
C. The genetic abnormality involves a proto-oncogene
D. Many patients develop parathyroid hyperplasia
E. Some patients may have a Marfanoid habitus

MEN I syndrome is characterized by the three Ps (pituitary adenoma, parathyroid hyperplasia, pancreatic carcinoma)sohe correct answer is D. Patients with MEN II (not MEN I) get medullary thyroid carcinoma, so A is wrong. The genetic abnormality in MEN II (not MEN I) involves the RET gene, so B is wrong. The bad gene in MEN I is a tumor suppressor gene, not a proto-oncogene, so C is wrong. There is no increased incidence of a Marfanoid habitus in MEN I (there is in some cases of MEN II though).


7. Which of the following is true regarding pheochromocytoma?

A. It can cause hypertension
B. It is usually an aggressive, malignant tumor
C. It only occurs in the adrenal gland
D. It is derived from neural crest cells
E. Many tumors have a 1p deletion

A is correct; pheochromocytomas can definitely present with hypertension. All that catecholamine release makes your blood pressure go up. Only about 10% of cases are malignant, so B is wrong. 10% of cases are extra-adrenal, so C is wrong. It is derived from the catecholamine-producing cells of the medulla (which are neural-crest derived)- so D is correct too! Chromosome 1 is not messed up in pheochromocytoma, so E is wrong. Some patients with neuroblastoma do have a deletion of the short arm of chromosome 1. By the way, the short arm was named “p” for “petit.” Cool, huh? Also, I always remember that q stands for the long arm because the letter q has a longer tail than the letter p.

 


8. Which of the following is true regarding Addison’s disease?

A. It is characterized by an overproduction of catecholamines
B. Most cases are due to infection
C. It is also called primary chronic adrenal insufficiency
D. The onset is sudden
E. Patients are often hypertensive

Addison’s disease is also called primary chronic adrenal insufficiency (so C is correct). It’s primary because the problem is localized to the adrenal itself (usually it’s an autoimmune thing, not an infectioius thing, so B is wrong), and it’s chronic (slowly progressive) as opposed to acute (like Waterhouse-Friderichson Syndrome).

It is not characterized by an overproduction of catecholamines (so A is wrong), but by an underproduction of everything the adrenal cortex makes: mineralocorticoids, glucocorticoids, and sex steroids. You don’t notice the sex steroid underproduction much, but you get symptoms from the lack of mineralocorticoids and cortisol for sure.

The onset is not sudden (so D is wrong). The onset of disease is slow and progressive – it takes a long, long time for the disease to eradicate enough of the adrenal to produce symptoms. The disease might present in what seems like an acute fashion – but if you look back, you’d be able to see signs that were present for a long time (like a tanned appearance, or fatigue).

Patients are not hypertensive; if anything, they are hypotensive because the lack of mineralocorticoids leads to a drop in blood sodium, which leads to a lower blood volume and hypertension. So E is wrong.

 


9. You are seeing a 41-year old male who is very tall and has a large jaw. You wonder if he might have acromegaly due to a pituitary adenoma. What laboratory test would be best for making this diagnosis?

A. Insulin-like growth factor level
B. Random serum growth hormone level
C. Prolactin level
D. Hemoglobin
E. Lactate dehydrogenase

Acromegaly is caused by a growth hormone-producing pituitary adenoma. You’d think you could just measure growth hormone, but since GH happens to be secreted in a pulsatile fashion, you can’t just take a random GH measurement; you wouldn’t know where on the curve the patient was (so B is wrong). Insulin-like growth factor is a surrogate marker that is made by the liver and released in a constant, non-pulsatile fashion. It’s what is usually measured in the workup of a GH producing pituitary adenoma. So A is correct.

 


10. Your sister is complaining that she is always tired, despite getting enough sleep. You notice that she seems pale, and when you feel her pulse it is quite slow. She also mentions that she can’t stand the cold these days. What two lab tests would be most helpful in diagnosing her condition?

A. FSH and LH levels
B. Free T4 and TSH levels
C. Calcium, phosphate, and parathyroid hormone levels
D.  Insulin-like growth factor and prolactin levels
E. Cortisol and ACTH levels

Tired all the time and pale could mean anemia. But since your sister has a slow pulse (not a fast one, like you’d expect in severe anemia) – and since that’s not one of the answers – we can rule that out.

Tired, pale, bradycardic (slow pulse) and cold is a great history for hypothyroidism. She also might feel depressed and may have gained weight recently. For hypothyroidism (or hyperthyroidism, for that matter), the best tests to get are a T4 (best to measure the free T4, because that’s the active fraction) and a TSH. The T4 is low in hypothyroidism, and if it’s a disease localized to the thyroid gland, like Hashimoto thyroiditis, the TSH will be high (because it’s responding to the puny amount of T4 put out by the thyroid gland). If the hypothyroidism is due to hypopituitarism (which is rare), then the TSH will be low (because that’s what’s driving the T4 down).

Endocrine quiz

How much do you know about endocrine pathology? Here’s a little quiz to help you find out. Answers with nice explanations will be posted tomorrow.

1. Which of the following is true of papillary thyroid carcinoma?

A. May have psammoma bodies
B. The least common kind of thyroid carcinoma
C. The type of thyroid carcinoma with the worst prognosis
D. Occurs in patients with MEN II
E. Most common in elderly patients

2. The most common cause of hypothyroidism in underprivileged countries is:

A. Pituitary dysfunction
B. DeQuervain’s thyroiditis
C. Graves’ disease
D. Hashimoto’s thyroiditis
E. Iodine deficiency

3. Which of the following hormones, in addition to participating in the initiation of labor, may play a role in trust, monogamy, and the desire to cuddle?

A. Cortisol
B. Thyroid hormone
C. Parathormone
D. Oxytocin
E. Antidiuretic hormone

4. A patient with Cushing syndrome might present with any of the following EXCEPT:

A. Obesity
B. A buffalo hump
C. Moon facies
D. Bronze or hyperpigmented skin
E. Glucose intolerance

5. Patients with diabetes have an increased risk of all of the following EXCEPT:

A. Cataracts
B. Infections
C. Increased atherosclerosis
D. Peripheral neuropathy
E. Pancreatic carcinoma

6. Which of the following is true regarding multiple endocrine neoplasia (MEN) I syndrome?

A. Virtually all patients develop medullary thyroid carcinoma
B. The genetic abnormality involves the RET gene
C. The genetic abnormality involves a proto-oncogene
D. Many patients develop parathyroid hyperplasia
E. Some patients may have a Marfanoid habitus

7. Which of the following is true regarding pheochromocytoma?

A. It can cause hypertension
B. It is usually an aggressive, malignant tumor
C. It only occurs in the adrenal gland
D. It is derived from neural crest cells
E. Many tumors have a 1p deletion

8. Which of the following is true regarding Addison’s disease?

A. It is characterized by an overproduction of catecholamines
B. Most cases are due to infection
C. It is also called primary chronic adrenal insufficiency
D. The onset is sudden
E. Patients are often hypertensive

9. You are seeing a 41-year old male who is very tall and has a large jaw. You wonder if he might have acromegaly due to a pituitary adenoma. What laboratory test would be best for making this diagnosis?

A. Insulin-like growth factor level
B. Random serum growth hormone level
C. Prolactin level
D. Hemoglobin
E. Lactate dehydrogenase

10. Your sister is complaining that she is always tired, despite getting enough sleep. You notice that she seems pale, and when you feel her pulse it is quite slow. She also mentions that she can’t stand the cold these days. What two lab tests would be most helpful in diagnosing her condition?

A. FSH and LH levels
B. Free T4 and TSH levels
C. Calcium, phosphate, and parathyroid hormone levels
D.  Insulin-like growth factor and prolactin levels
E. Cortisol and ACTH levels

Thyroid lab tests explained in under 150 words

Q. I have been trying to figure out the two basic thyroid lab tests, TSH and T4. If you have a high TSH and a low T4 does that mean that the pituitary gland is going crazy to reach homeostasis but the thyroid is not responding? And inversely, if the T4 is high and the TSH is low does that mean for some reason the thyroid is working overtime due to a disease like Graves disease, and the pituitary is trying to compensate by not producing TSH?

A. Yes! That’s exactly right. When the two (TSH and T4) are opposite of each other – high T4/low TSH or low T4/high TSH – that means that the problem is intrinsic to the thyroid gland (Graves disease or Hashimoto thyroiditis, for example) and the pituitary is trying to control the thyroid by producing more or less TSH. Those are the most common types of thyroid disease – those that are intrinsic, or primary to the thyroid gland itself.

On the other hand, if both TSH and T4 are either low or high – high T4/high TSH or low T4/low TSH – that means that the process is being driven by TSH. Either there’s a pituitary adenoma making a ton of TSH, or the pituitary is not working well for whatever reason (it’s been radiated, or has undergone necrosis) and it’s not making enough TSH.

Image credit: akay (http://www.flickr.com/photos/akay/245002004/), under cc license.