Internal medicine - Endocrinology (48) Flashcards
INT - 11.1
Main manifestations of multiple endocrine neoplasia type 1 (MEN1):
A) pheochromocytoma, hyperparathyroidism, Leydig-cell testicle tumor
B) pheochromocytoma, hyperparathyroidism, pituitary adenoma
C) hyperparathyroidism, pancreas neuroendocrine tumor, pituitary adenoma
D) pheochromocytoma, medullary thyroid carcinoma, pituitary adenoma
E) hyperparathyroidism, pheochromocytoma, pituitary adenoma
ANSWER
C) hyperparathyroidism, pancreas neuroendocrine tumor, pituitary adenoma
EXPLANATION
Multiple endocrine neoplasia type 1 (MEN1) is an endocrine tumor syndrome with autosomal dominant inheritance. The disorder is caused by the mutations of the MEN1 gene encoding menin protein. Its main manifestations are primary hyperparathyroidism (in about 90% of cases), pituitary adenoma (in 30-75% of cases) and neuroendocrine tumor of the pancreas (in 10-60% of cases). Primary hyperparathyroidism usually appears as the first component of the syndrome, in young (20-30-year-old) adults. In patients suffering from MEN1 syndrome foregut carcinoid tumor (thymus, bronchus, stomach), adrenocortical tumor (most commonly hormonally inactive adenoma) and non-endocrine tumors (lipoma, angiofibroma, collagenoma) may also appear, but these tumors are considered accessory components of the syndrome. Patients and relatives carrying the disease causing mutation have to be screened regularly for these tumors. Pheochromocytoma and medullary thyroid cancer are components of multiple endocrine neoplasia type 2 (MEN2), not MEN1. Leydig cell tumor is also not a component of MEN1 syndrome, but Carney complex.
INT - 11.2
The appropriate test to certify acromegaly:
A) investigation of the diurnal rhythm of serum growth hormone (GH) concentration
B) investigation of the serum growth hormone (GH) concentration in morning hours
C) investigation of the serum growth hormone (GH) concentration during oral glucose tolerance test
D) investigation of the serum growth hormone (GH) concentration after administration of growth hormone-releasing hormone (GHRH)
ANSWER
C) investigation of the serum growth hormone (GH) concentration during oral glucose tolerance test
EXPLANATION
Growth hormone (GH) secretion is characterized by a diurnal rhythm and pulsatile excretion. The most important characteristic of diurnal rhythm is GH secretion during night sleep and consecutive high serum GH level, while pulsatile excretion manifests itself in high GH peaks about 13 times a day. Because of the intense variability of GH secretion, the determination of morning serum GH level and diurnal rhythm of serum GH is not suitable for diagnosing acromegaly. Serum GH measurement after the administration of growth hormone-releasing hormone (GHRH) is used to examine the GH-producing ability of the pituitary; it is applied not in the diagnosis of acromegaly, but in GH deficiency. For the confirmation or exclusion of acromegaly the most commonly used and most reliable method is serum GH determination during oral glucose tolerance test (OGTT). Acromegaly is confirmed, if serum GH level remains above 1 ng/ml in blood samples taken every 30 minutes for two hours after the administration of 75 grams of glucose. If OGTT is not feasible (e.g. in diabetic patients) GH profile examination is recommended (e.g. serum GH measurement every 30 minutes 7-12 times).
INT - 11.3
It is characteristic for subclinical primary hypothyroidism:
A) clinical signs of hypothyroidism with normal serum thyroid hormone levels
B) the hormone levels refer to primary hypothyroidism without clinical signs
C) low free T4 and free T3 levels with normal serum TSH
D) normal free T4 and free T3 levels with elevated serum TSH
ANSWER
D) normal free T4 and free T3 levels with elevated serum TSH
EXPLANATION
Subclinical primary hypothyroidism is characterized by normal serum free T4 and free T3 levels and serum TSH level above the reference range. The elevation of serum TSH is relatively moderate; significantly higher TSH levels are usually associated with decreased serum free T4 and/or serum free T3 levels (primary hypothyroidism).
INT - 11.4
Primary therapy of prolactin-producing pituitary microadenoma:
A) pituitary surgery
B) pituitary irradiation
C) treatment with dopamine agonist
D) treatment with dopamine antagonist
E) treatment with somatostatin analogue
ANSWER
C) treatment with dopamine agonist
EXPLANATION
For the primary treatment of prolactin-producing pituitary microadenoma dopamine agonist drugs are applied. In Hungary the drug of choice is bromocriptine, that is given usually twice daily (the higher dose in the evening), with a low initial and gradually increased dose. Bromocriptine is a D2 dopamine receptor agonist ergoline derivative. For patients with pituitary microadenoma the average sustained daily dose of bromocriptine is 2.5-7.5 mg. Bromocriptine therapy corrects prolactin levels in 80-90% of prolactin-producing pituitary microadenoma cases, and after a few months of treatment gonadal function recovers. In 60-70% of patients the size of the pituitary microadenoma also decreases, and total tumor regression may also occur. After the discontinuation of short-term bromocriptine treatment hormonal disorders and clinical symptoms usually recur, therefore in most cases long-term (through years) treatment is needed. In case of prolactin-producing pituitary microadenoma a pituitary operation is considered only in special cases (e.g. bromocriptine intolerance or -resistance). Radiotherapy is not used in prolactin-producing pituitary microadenoma. Dopamine antagonist drugs lead to hyperprolactinemia, and are not used in prolactin-producing pituitary microadenoma. Somatostatin analogues are not used either in the treatment of prolactin-producing pituitary microadenoma.
INT - 11.5
In case of a patient receiving thyroid hormone substitution due to a thyroid ablation therapy of papillary thyroid carcinoma, laboratory results show a suppression of TSH level and normal free T4 and free T3 levels. Is it necessary to modify the dose of the thyroid hormone substitution (l-thyroxin)?
A) the dose of l-thyroxin is appropriate, no modification is needed
B) reduction of the daily dose of l-thyroxin is necessary due to the suppressed TSH
C) increase of the daily dose of l-thyroxin is necessary due to the suppressed TSH
D) no modification of the dose of l-thyroxin is needed, but we shall give thyreostatics in addition
ANSWER
A) the dose of l-thyroxin is appropriate, no modification is needed
EXPLANATION
TSH, in addition to stimulating hormone production of the thyroid gland, also increases thyroid cell proliferation. This effect shows also on differentiated thyroid cancer (papillary and follicular thyroid cancer) cells. Thus after the ablation therapy of differentiated thyroid cancer the thyroid hormone substitution is adjusted to a dose that keeps TSH level well below the reference range. According to the current practice, the thyroid hormone treatment for the suppression of TSH is maintained for 5 years after thyroid cancer ablation; after this, in cases without recurrent cancer the dose of thyroid hormone supplementation is set to a dose that keeps serum TSH level in the normal range. Administration of thyrostatic drugs after thyroid cancer ablation would cause at most adverse side effects of these products (agranulocytosis, hepatopathy), because in the absence of thyroid hormone producing cells thyrostatic drugs do not affect TSH levels.
INT - 11.6
We can use it as a serum marker of medullary thyroid carcinoma:
A) investigation of serum thyreoglobulin
B) investigation of serum calcitonin
C) investigation of serum osteocalcin
D) investigation of serum parathyroid hormone
ANSWER
B) investigation of serum calcitonin
EXPLANATION
Medullary thyroid cancer is the tumor of the thyroid parafollicular C-cells. Parafollicular C-cells synthesize calcitonin; the calcitonin-producing ability is maintained in cancerously transformed cells. Elevated serum calcitonin level is a specific marker of medullary thyroid cancer, although rarely other tumors may also produce calcitonin (e.g. insulinoma). After the successful removal of medullary thyroid cancer, serum calcitonin level returns to normal; a renewed increase indicates recurrence or metastasis. In medullary thyroid cancer serum carcinoembryonic antigen (CEA) level is also enhanced. Serum thyroglobulin determination serves as an important tumor marker after ablation of differentiated thyroid cancer. Serum osteocalcin is the marker of bone metabolism, while serum parathyroid hormone is used for the examination of diseases and dysfunction of the parathyroid glands.
INT - 11.7
Endocrine disorders causing diarrhea, except:
A) medullary thyroid carcinoma
B) gastrinoma
C) carcinoid tumor
D) pheochromocytoma
ANSWER
D) pheochromocytoma
EXPLANATION
Diarrhea is a leading symptom of carcinoid syndrome evolving in case of carcinoid tumors. Gastrinoma, besides other symptoms (like recurrent multiple peptic ulcers that hardly react to treatment), is also characterised by diarrhea. Diarrhea is also common in case of medullary thyroid cancer with multiple metastases and significantly elevated serum calcitonin level. In contrast to these three tumors, pheochromocytoma is characterized by constipation due to the mesenteric vasospasm caused by catecholamine overproduction.
INT - 11.8
The appropriate test for the clarification of Cushing’s syndrome, except:
A) investigation of 24 hour urinary free cortisol (UFC) excretion
B) investigation of serum cortisol after administration of low dose dexamethasone
C) investigation of the diurnal rhythm of serum cortisol
D) investigation of serum cortisol in morning hours
E) investigation of the diurnal rhythm of salivary cortisol
ANSWER
D) investigation of serum cortisol in morning hours
EXPLANATION
For the screening of Cushing’s syndrome we use tests that determine the daily integrated cortisol secretion, the diurnal rhythm of cortisol secretion, and the feed-back regulating function of the pituitary-adrenal axis. These tests include the examination of 24 hour urine cortisol, diurnal rhythm of serum or saliva cortisol (in samples taken at midnight and between 8-9 o’clock in the morning), and serum cortisol level after the administration of low dose dexamethasone (in the so-called low dose overnight dexamethasone test serum cortisol is measured from a sample taken between 8-9 o’clock in the morning, after having administered 1 mg dexamethasone the previous midnight). Stressful circumstances can significantly increase serum cortisol level, and on the other hand Cushing’s syndrome can be present without the significant elevation of morning serum cortisol (because of the lack of diurnal rhythm, i.e. failure of the physiologic decrease of cortisol level after the morning hours). Thus serum cortisol examination in the morning alone is not sufficient for the screening of Cushing’s syndrome in the clinical practice.
INT - 11.9
Radioiodine treatment can be used against the following diseases, except:
A) after the surgery of papillary thyroid carcinoma
B) after the surgery of follicular thyroid carcinoma
C) after the surgery of medullary thyroid carcinoma
D) autonomous thyroid nodule causing hyperthyroidism
E) Graves’ disease
ANSWER
C) after the surgery of medullary thyroid carcinoma
EXPLANATION
Radioiodine treatment is an important therapeutic tool for total thyroid ablation after total (near total) thyroidectomy in case of differentiated thyroid cancer (papillary and follicular thyroid cancer), for the treatment of autonomous thyroid nodules causing hyperthyroidism, and for the cessation of thyroid overproduction in Graves’ disease. Medullary thyroid cancer cells originating from the thyroid parafollicular C-cells do not have iodine uptake ability (due to the lack of sodium/iodide symporter that is necessary for iodine uptake), therefore radioiodine is not used in the treatment of medullary thyroid cancer.
INT - 11.10
It is characteristic for primary aldosteronism:
A) suppression of plasma renin and high plasma aldosteron
B) high plasma renin and high plasma aldosteron
C) normal plasma renin and high plasma aldosteron
D) high plasma aldosteron, plasma renin is not relevant
ANSWER
A) suppression of plasma renin and high plasma aldosteron
EXPLANATION
Primary aldosteronism is caused by autonomous (or partly autonomous) aldosterone overproduction of the adrenal cortex. The sodium- and water-retaining effect of excess aldosterone inhibits the secretion of renin produced in the kidney, that leads to decreased renin level. Primary aldosteronism is characterized by high plasma aldosterone and suppressed renin levels.
INT - 11.11
In case of a patient with pituitary macroadenoma, double vision evolved. What can be the reason for that?
A) suprasellar spread of the pituitary macroadenoma
B) lateral spread of the pituitary macroadenoma to the cavernous sinus
C) downward spread of the pituitary macroadenoma and penetration into the sphenoid sinus
D) there is no connection between the pituitary macroadenoma and the double vision
ANSWER
B) lateral spread of the pituitary macroadenoma to the cavernous sinus
EXPLANATION
Pituitary macroadenoma may lead to so-called compression symptoms through the compression of the adjacent structures. The oculomotor nerves reach the oculomotor muscles through the cavernous sinus located next to the sella, therefore the lateral growth of the pituitary macroadenoma may cause the injury of the nerves innervating oculomotor muscles and consecutive diplopia. The suprasellar spreading of pituitary macroadenoma does not cause diplopia, however, may lead to visual field defect (bitemporal hemianopsia) or blindness due to the injury of the optic chiasm located above the sella. The downward growth of pituitary macroadenoma does not cause diplopia either, but may lead to nasal liquorrhea through the penetration of the sphenoidal sinus wall.
INT - 11.12
It is characteristic for the lack of growth hormone (GH) in adults, except:
A) it is associated with unfavorable lipid profile
B) it is associated with increased water content of the body and water retention
C) it is associated with unfavorable fat/muscle mass ratio
D) it is associated with weakness and discomfort
ANSWER
B) it is associated with increased water content of the body and water retention
EXPLANATION
Growth hormone (GH) deficiency in adulthood is associated with - among others - unfavorable serum lipid parameters, increased body fat/muscle mass ratio, fatigue, weakness, and general malaise. Water content of the body does not increase, moreover, in adulthood GH deficiency causes reduced body water content.
INT - 11.13
Diseases with polyuria, except:
A) primary aldosteronism
B) primary hyperparathyroidism
C) diabetes insipidus
D) diabetes mellitus
E) SIADH (syndrome of inappropriate antidiuretic hormone secretion)
ANSWER
E) SIADH (syndrome of inappropriate antidiuretic hormone secretion)
EXPLANATION
Polyuria (and polydipsia) are well-known symptoms of diabetes insipidus and diabetes mellitus; in total central diabetes insipidus the lack of antidiuretic hormone (ADH) can cause as much as 18-20 liters of urine daily. Primary aldosteronism with prolonged hypokalemia and primary hyperparathyroidism with prolonged hypercalcemia cause the insensitivity of the vasopressin receptors of the kidney tubules (renal diabetes insipidus), and thus lead to polyuria in these diseases. Out of the listed diseases only SIADH (syndrome of inappropriate ADH secretion) is not associated with polyuria.
INT - 11.14
It can be the cause of growth hormone (GH) deficiency in adults:
A) pituitary tumor
B) skull trauma
C) radiotherapy
D) pituitary apoplexia
E) all of the above
ANSWER
E) all of the above
EXPLANATION
GH-deficiency in adults can be caused by many processes that damage pituitary and/or hypothalamus function, including all of the listed causes (pituitary tumor, skull trauma, radiotherapy, pituitary apoplexia).
INT - 11.15
Diseases with hirsutism, except:
A) Cushing’s disease
B) hypopituitarism
C) polycystic ovary syndrome
D) 21-hydroxylase deficiency form of congenital adrenal hyperplasia
ANSWER
B) hypopituitarism
EXPLANATION
Cushing’s disease may be associated with hirsutism in women; increased ACTH secretion due to ACTH-producing pituitary adenoma induces not only adrenal cortisol, but also adrenal androgen synthesis. In polycystic ovary syndrome hirsutism is caused by the increased production of both ovarian and adrenal androgens. The 21-hydroxylase deficiency form of congenital adrenal hyperplasia is associated with the overproduction of androgen hormones, and this leads to hirsutism in women. In contrast to these three diseases, in hypopituitarism, due to the central decrease of gonadal and adrenal function, the androgen production of both the gonads and adrenal glands decreases, that leads to scant body hair or even the total loss of body hair.
INT - 11.16
Hereditary tumor syndromes with pheochromocytoma:
1) von Hippel–Lindau syndrome
2) multiple endocrine neoplasia type 2
3) neurofibromatosis type 1
4) multiple endocrine neoplasia type 1
A) answers 1, 2 and 3 are correct
B) answers 1 and 3 are correct
C) answers 2 and 4 are correct
D) only answer 4 is correct
E) all four answers are correct
ANSWER
A) answers 1, 2 and 3 are correct
EXPLANATION
Pheochromocytoma can be a phenomenon of three of the listed hereditary tumor syndromes (von Hippel–Lindau syndrome, multiple endocrine neoplasia type 2, neurofibromatosis type 1), but it is not typical in multiple endocrine neoplasia type 1.
INT - 11.17
Which are tumor suppressor genes of the followings?
1) RET
2) MEN1 (menin protein encoding gene)
3) RAS
4) VHL
A) answers 1., 2., and 3 are correct
B) answers 1. and 3. are correct
C) answers 2. and 4. are correct
D) only answer 4 is correct
E) all four answers are correct
ANSWER
C) answers 2. and 4. are correct
EXPLANATION
Two of the listed genes belong to the group of tumor suppressor genes: MEN1, responsible for multiple endocrine neoplasia type 1 and VHL gene causing von Hippel–Lindau syndrome. RET and RAS genes are oncogenes. The characteristic of tumor suppressor genes is that the defect of both alleles (e.g. the germinal mutation of one allele and somatic mutation of the other allele) leads to tumor formation. On the contrary, the effect of oncogenes is dominant, i.e. the disease-causing mutation of one of the alleles is enough for tumor formation.
INT - 11.18
It may be a symptom of Graves’ disease:
1) diarrhea
2) tachycardia
3) pretibial myxedema
4) fine hand tremor
A) answers 1., 2. and 3 are correct
B) answers 1. and 3. are correct
C) answers 2. and 4. are correct
D) only answer 4 is correct
E) all four answers are correct
ANSWER
E) all four answers are correct
EXPLANATION
All four listed symptoms are characteristic for Graves’ disease (diarrhea, tachycardia, pretibial myxedema, fine hand tremor).
INT - 11.19
Which are glycoprotein hormones of the followings?
1) TSH (thyroid-stimulating hormone)
2) LH (luteinizing hormone)
3) hCG (human chorionic gonadotropin)
4) FSH (follicle stimulating hormone)
A) answers 1., 2., and 3 are correct
B) answers 1. and 3. are correct
C) answers 2. and 4. are correct
D) only answer 4 is correct
E) all four answers are correct
ANSWER
E) all four answers are correct
EXPLANATION
All of the listed hormones are glycoprotein hormones (TSH, LH, hCG, FSH). The common trait of this hormone family is that all members consist of two subunits; the alpha-subunit is identical in all four hormones, while the different beta-subunits are responsible for the specific biological effect of the various glycoprotein hormones.
