Block 13 Pituitary Hypothal Disorder Drugs

1. Which cell type produces growth hormone ?

Neurosecretory cells of paraventricular nuclei

Pituicytes

Corticotrophs

Somatotrophs

Hepatocytes

Somatotrophs are the cell type that produces growth hormone. Growth hormone is a hormone that stimulates growth, cell reproduction, and regeneration in humans and other animals. Somatotrophs are found in the anterior pituitary gland and are responsible for the secretion of growth hormone.

Explanation

Somatotrophs are the cell type that produces growth hormone. Growth hormone is a hormone that stimulates growth, cell reproduction, and regeneration in humans and other animals. Somatotrophs are found in the anterior pituitary gland and are responsible for the secretion of growth hormone.

2. Following brain surgery, a patient receiving postoperative care in an intensive care unit began to produce large volumes of dilute urine. The patient is administered an analogue of which of the following hormones?

Aldosterone

Vasopressin

Oxytocin

Cortisol

Epinephrine

After brain surgery, the patient started producing large volumes of dilute urine, which suggests a condition called diabetes insipidus. This condition is caused by a deficiency or resistance to the hormone vasopressin, also known as antidiuretic hormone (ADH). Vasopressin is responsible for regulating water reabsorption in the kidneys, so when it is lacking, the kidneys are unable to concentrate urine, leading to the production of large volumes of dilute urine. Administering an analogue of vasopressin would help to compensate for the deficiency and improve urine concentration.

Explanation

After brain surgery, the patient started producing large volumes of dilute urine, which suggests a condition called diabetes insipidus. This condition is caused by a deficiency or resistance to the hormone vasopressin, also known as antidiuretic hormone (ADH). Vasopressin is responsible for regulating water reabsorption in the kidneys, so when it is lacking, the kidneys are unable to concentrate urine, leading to the production of large volumes of dilute urine. Administering an analogue of vasopressin would help to compensate for the deficiency and improve urine concentration.

3. A 35-year-old woman presented to the clinic complaining of continuous thirst and polyuria. She had had a basal skull fracture following a car accident six month previously from which she recovered completely. She reported that she often awoke at night because of thirst and a need to urinate. Urinalysis showed a urine osmolality of 20 mOsm/Kg and undetectable plasma ADH levels. Which if the following drugs would be appropriate for the patient?

Conivaptan

Sermorelin

Desmopressin

Octreotide

Bromocriptine

The patient's symptoms of continuous thirst and polyuria, along with the low urine osmolality and undetectable plasma ADH levels, suggest a diagnosis of central diabetes insipidus. Desmopressin is a synthetic form of ADH, which can replace the deficient hormone in patients with central diabetes insipidus. Therefore, desmopressin would be an appropriate drug for this patient to manage her symptoms.

Explanation

The patient's symptoms of continuous thirst and polyuria, along with the low urine osmolality and undetectable plasma ADH levels, suggest a diagnosis of central diabetes insipidus. Desmopressin is a synthetic form of ADH, which can replace the deficient hormone in patients with central diabetes insipidus. Therefore, desmopressin would be an appropriate drug for this patient to manage her symptoms.

4. A 28 year-old woman attends her doctor because she has not had a menstrual cycle of two months, but commercial pregnancy tests have proven negative. She reports that a few weeks before her expected menstrual cycle was missed, she had suffered an accident in a gym, in which she had fallen from a climbing rope from a height of around 10 feet. She had fallen "head-first" onto some weight-training equipment, and although she had not lost consciousness, she sustained bruising on the left side of her face around her cheek, eye and temples. The woman reports that following the accident she had noticed that she was feeling continually fatigued, and had gained weight. She feels thirsty most of the time and is perplexed as to why she needs to urinate more often than before. Physical examination confirms that the woman is not pregnant and reveals traces of a white crystalline deposit around her nipples. The level of which hormone would be expected to be elevated in the plasma of this patient?

Luteunizing Hormone (LH)

Thyroid Stimulating Hormone (TSH)

Follicle Stimulating Hormone FSH)

Oxytocin

Prolactin (Prl)

The woman's symptoms, such as missed menstrual cycles, weight gain, fatigue, increased thirst, and frequent urination, along with the presence of a white crystalline deposit around her nipples, suggest that she may be experiencing hyperprolactinemia. Prolactin is responsible for milk production and can suppress ovulation and menstruation. In this case, the trauma to the head from the gym accident may have caused an increase in prolactin levels, leading to the absence of menstrual cycles and other symptoms. Therefore, the level of prolactin would be expected to be elevated in the plasma of this patient.

Explanation

The woman's symptoms, such as missed menstrual cycles, weight gain, fatigue, increased thirst, and frequent urination, along with the presence of a white crystalline deposit around her nipples, suggest that she may be experiencing hyperprolactinemia. Prolactin is responsible for milk production and can suppress ovulation and menstruation. In this case, the trauma to the head from the gym accident may have caused an increase in prolactin levels, leading to the absence of menstrual cycles and other symptoms. Therefore, the level of prolactin would be expected to be elevated in the plasma of this patient.

5. Which of the following statements concerning the embryology of the pituitary gland is CORRECT?

The anterior pituitary is derived from the mesencephalon

Rathke’s pouch is derived from the posterior pituitary

The Pars Distalis is derived from endoderm

Mesoderm gives rise to the anterior pituitary

Neuroectoderm gives rise to the neurohypophysis

The neuroectoderm gives rise to the neurohypophysis, which is the posterior pituitary gland. The neurohypophysis is derived from a downgrowth of the hypothalamus during embryonic development. The anterior pituitary gland, also known as the adenohypophysis, is derived from the oral ectoderm. The mesencephalon is not involved in the development of the pituitary gland.

Explanation

The neuroectoderm gives rise to the neurohypophysis, which is the posterior pituitary gland. The neurohypophysis is derived from a downgrowth of the hypothalamus during embryonic development. The anterior pituitary gland, also known as the adenohypophysis, is derived from the oral ectoderm. The mesencephalon is not involved in the development of the pituitary gland.

6. A 6-year-old boy of short stature is given a subcutaneous injection of growth hormone releasing hormone (GHRH) and blood samples are taken 1 hour later for measurement of plasma growth hormone (GH). Laboratory results demonstrated an increase in GH concentration following the injection of GHRH. What would be the most likely conclusion based upon these findings?

The patient’s short stature is most likely explained by inadequate hypothalamic release of GHRH

The patients’ short stature is most likely explained by inability of somatotrophs to release GH.

The liver cannot produce insulin-like growth factor-1 (IGF-1).

Somatotrophes of the anterior pituitary are inactive because of hypersecretion of somatostatin.

Endogenous GHRH had suppressed the release of somatostatin.

Based on the given information, the most likely conclusion is that the patient's short stature is explained by inadequate hypothalamic release of GHRH. This is because the injection of GHRH resulted in an increase in GH concentration, suggesting that the patient's body is not producing enough GHRH on its own. GHRH is responsible for stimulating the release of GH, which is necessary for normal growth and development. Therefore, inadequate release of GHRH would result in a deficiency of GH and ultimately lead to short stature.

Explanation

Based on the given information, the most likely conclusion is that the patient's short stature is explained by inadequate hypothalamic release of GHRH. This is because the injection of GHRH resulted in an increase in GH concentration, suggesting that the patient's body is not producing enough GHRH on its own. GHRH is responsible for stimulating the release of GH, which is necessary for normal growth and development. Therefore, inadequate release of GHRH would result in a deficiency of GH and ultimately lead to short stature.

7. Which of the following statements concerning the pituitary gland is CORRECT?

TSH is derived from the hypothalamus

TSH is stored in the pars nervosa of the pituitary gland

Herring bodies store oxytocin and FSH

Somatotrophs are acidophils and they produce GH

Chromophobes secrete oxytocin and vasopressin

Somatotrophs are acidophils and they produce GH. This statement is correct because somatotrophs are a type of cells in the anterior pituitary gland that produce growth hormone (GH). Acidophils are one of the two types of cells in the anterior pituitary gland, the other being basophils.

Explanation

Somatotrophs are acidophils and they produce GH. This statement is correct because somatotrophs are a type of cells in the anterior pituitary gland that produce growth hormone (GH). Acidophils are one of the two types of cells in the anterior pituitary gland, the other being basophils.

8. The presence of a tumor in the anterior pituitary causes a decrease in ACTH secretion. Which of the following correctly describes changes in plasma levels of hormones?

Increased CRH, increased ACTH, and increased cortisol

Decreased CRH, decreased ACTH, and decreased cortisol

Increased CRH, decreased ACTH, and decreased cortisol

Increased CRH, increased ACTH, and decreased cortisol

Decreased CRH, decreased ACTH, and increased cortisol

A tumor in the anterior pituitary causes a decrease in ACTH secretion. ACTH is responsible for stimulating the secretion of cortisol from the adrenal cortex. Therefore, with decreased ACTH levels, cortisol secretion will also decrease. However, the decrease in cortisol levels will lead to an increase in CRH secretion from the hypothalamus, as the body tries to compensate for the low cortisol levels. Therefore, the correct answer is "Increased CRH, decreased ACTH, and decreased cortisol."

Explanation

A tumor in the anterior pituitary causes a decrease in ACTH secretion. ACTH is responsible for stimulating the secretion of cortisol from the adrenal cortex. Therefore, with decreased ACTH levels, cortisol secretion will also decrease. However, the decrease in cortisol levels will lead to an increase in CRH secretion from the hypothalamus, as the body tries to compensate for the low cortisol levels. Therefore, the correct answer is "Increased CRH, decreased ACTH, and decreased cortisol."

9. A 30-year-old pregnant woman at term was started oxytocin to induce labor. It acts as uterine stimulant by which of the following mechanisms?

Activating IP3-DAG-Ca+2 pathway

Activating cAMP pathway

Activating cGMP-NO pathway

Activating Na+-K+ channels

Oxytocin acts as a uterine stimulant by activating the IP3-DAG-Ca+2 pathway. This pathway involves the activation of inositol triphosphate (IP3) and diacylglycerol (DAG), which ultimately leads to an increase in intracellular calcium (Ca+2) levels. Increased intracellular calcium levels in uterine smooth muscle cells result in increased contractility and uterine contractions, which can help to induce labor.

Explanation

Oxytocin acts as a uterine stimulant by activating the IP3-DAG-Ca+2 pathway. This pathway involves the activation of inositol triphosphate (IP3) and diacylglycerol (DAG), which ultimately leads to an increase in intracellular calcium (Ca+2) levels. Increased intracellular calcium levels in uterine smooth muscle cells result in increased contractility and uterine contractions, which can help to induce labor.

10. A 32-year old man was admitted to the hospital because of prolonged, massive watery diarrhea for the last two days. Physical and lab exams indicated a pancreatic tumor and radioimmunoassay confirmed the diagnosis of vipoma. The patient was given IV fluids for hydration and was scheduled for surgery. Which of the following drugs would be appropriate to control the patient's diarrhea?

Somatotropin

Conivaptan

Bromocriptine

Octreotide

Cabergoline

Octreotide would be the appropriate drug to control the patient's diarrhea in this case. Vipoma is a pancreatic tumor that secretes vasoactive intestinal peptide (VIP), which causes watery diarrhea. Octreotide is a synthetic analogue of somatostatin, a hormone that inhibits the secretion of various gastrointestinal hormones, including VIP. By administering octreotide, the excessive secretion of VIP can be suppressed, leading to a reduction in the patient's diarrhea.

Explanation

Octreotide would be the appropriate drug to control the patient's diarrhea in this case. Vipoma is a pancreatic tumor that secretes vasoactive intestinal peptide (VIP), which causes watery diarrhea. Octreotide is a synthetic analogue of somatostatin, a hormone that inhibits the secretion of various gastrointestinal hormones, including VIP. By administering octreotide, the excessive secretion of VIP can be suppressed, leading to a reduction in the patient's diarrhea.

11. Both the anterior and posterior pituitary glands depend upon input from hypothalamic nuclei for release of pituitary hormones. In the following table which row correctly lists the type of connections between the hypothalamus and the anterior and posterior pituitary glands?

	Hypothalamus to anterior pituitary	Hypothalamus to posterior pituitary
A	Axonal connections	Axonal connections
B	Releasing factors	Releasing factors
C	Axonal connections	Releasing factors
D	Releasing factors	Axonal connections

A

B

C

D

The correct answer is D because the hypothalamus releases releasing factors that travel through the blood vessels to the anterior pituitary gland, where they stimulate the release of hormones. On the other hand, the hypothalamus has direct axonal connections to the posterior pituitary gland, allowing it to release hormones directly into the bloodstream.

Explanation

The correct answer is D because the hypothalamus releases releasing factors that travel through the blood vessels to the anterior pituitary gland, where they stimulate the release of hormones. On the other hand, the hypothalamus has direct axonal connections to the posterior pituitary gland, allowing it to release hormones directly into the bloodstream.

12. A 29 year old woman is diagnosed with acromegaly. Typically, she would exhibit which one of the following abnormalities?

Hypoglycemia

Decreased gluconeogenesis

Insulin resistance

Decreased protein synthesis

Increased storage of fat in adipose tissue

Insulin resistance is commonly observed in individuals with acromegaly. Acromegaly is a condition caused by excessive growth hormone production, usually due to a pituitary adenoma. The excess growth hormone leads to increased insulin levels, which can result in insulin resistance. This means that the body's cells do not respond effectively to insulin, leading to impaired glucose uptake and utilization. As a result, blood sugar levels may remain elevated, leading to hyperglycemia. Therefore, insulin resistance is the expected abnormality in a 29-year-old woman diagnosed with acromegaly.

Explanation

Insulin resistance is commonly observed in individuals with acromegaly. Acromegaly is a condition caused by excessive growth hormone production, usually due to a pituitary adenoma. The excess growth hormone leads to increased insulin levels, which can result in insulin resistance. This means that the body's cells do not respond effectively to insulin, leading to impaired glucose uptake and utilization. As a result, blood sugar levels may remain elevated, leading to hyperglycemia. Therefore, insulin resistance is the expected abnormality in a 29-year-old woman diagnosed with acromegaly.

13. A 52-year-old man was admitted to the hospital because of a sharp substernal pain of one hour duration. On admission the patient lost consciousness and physical examination revealed nonpalpable pulses and absent heart sounds. Cardioversion was tried without success, then cardiopulmonary resuscitation was started and a large dose of vasopressin was given IV. The beneficial effect of the drug in this setting seems mainly mediated by which of the following actions?

The increased venous return to the heart

The decreased water diuresis

The cerebral vasodilation

The positive inotropic effect

The decreased cardiac automaticity

The beneficial effect of the large dose of vasopressin in this situation is mainly mediated by the increased venous return to the heart. This means that the vasopressin helps to improve blood flow back to the heart, which can be beneficial in a situation where the patient has lost consciousness and has nonpalpable pulses and absent heart sounds. By increasing venous return, the vasopressin can help to improve cardiac output and perfusion to vital organs.

Explanation

The beneficial effect of the large dose of vasopressin in this situation is mainly mediated by the increased venous return to the heart. This means that the vasopressin helps to improve blood flow back to the heart, which can be beneficial in a situation where the patient has lost consciousness and has nonpalpable pulses and absent heart sounds. By increasing venous return, the vasopressin can help to improve cardiac output and perfusion to vital organs.

14. A 35-year-old man presented to the hospital with a history of joint pain, headache, excessive sweating, and deepening of the voice. A physical examination revealed protrusion of the jaw, enlargement of the hands, thickening of the skin, and a barrel chest. A CT scan disclosed a pituitary adenoma and the patient underwent radiotherapy. Which of the following drugs was most likely prescribed while waiting for radiotherapy to work?

Somatrem

Sermorelin

Somatropin

Octreotide

Cabergoline

Octreotide is a somatostatin analog that inhibits the release of growth hormone from the pituitary gland. In this case, the patient has symptoms consistent with acromegaly, which is caused by excessive production of growth hormone from a pituitary adenoma. Octreotide would be prescribed to help control the symptoms of acromegaly while waiting for radiotherapy to work. It can help reduce the excessive growth hormone levels and alleviate symptoms such as joint pain, headache, excessive sweating, and deepening of the voice.

Explanation

Octreotide is a somatostatin analog that inhibits the release of growth hormone from the pituitary gland. In this case, the patient has symptoms consistent with acromegaly, which is caused by excessive production of growth hormone from a pituitary adenoma. Octreotide would be prescribed to help control the symptoms of acromegaly while waiting for radiotherapy to work. It can help reduce the excessive growth hormone levels and alleviate symptoms such as joint pain, headache, excessive sweating, and deepening of the voice.

15. A laboratory experiment was performed utilizing microscope-florescence-imaging of a Ca⁺⁺ - sensitive dye (a technique that enables investigators to monitor intracellular Ca⁺⁺) on freshly isolated cells from the anterior pituitary gland of a mouse. On addition of a newly discovered peptide hormone to the fluid bathing the cells, it was observed that intracellular Ca⁺⁺ increased in some cells but not in others. All cells were determined as viable (alive) by an independent test. What is the most likely explanation for the failure of some cells to respond to the hormone?

Chemical signals are only exposed to specific cells

Some cells are completely without receptors

Some cells are completely without ligands

Signal chemicals often break down before reaching the target.

Some cells lack the necessary receptors

Some cells lack the necessary receptors to bind and respond to the newly discovered peptide hormone, which is why they did not show an increase in intracellular Ca++. This suggests that the hormone can only interact with cells that have the appropriate receptors for it.

Explanation

Some cells lack the necessary receptors to bind and respond to the newly discovered peptide hormone, which is why they did not show an increase in intracellular Ca++. This suggests that the hormone can only interact with cells that have the appropriate receptors for it.

16. Which drug for treating acromegaly acts by blocking receptors for growth hormone?

Somatropin

Pegvisomant

Octreotide

Desmopressin

Cabergoline

Pegvisomant is the correct answer because it acts by blocking receptors for growth hormone. This drug is used in the treatment of acromegaly, a condition characterized by excessive growth hormone production. By blocking the receptors, pegvisomant prevents the actions of growth hormone, reducing the symptoms associated with acromegaly.

Explanation

Pegvisomant is the correct answer because it acts by blocking receptors for growth hormone. This drug is used in the treatment of acromegaly, a condition characterized by excessive growth hormone production. By blocking the receptors, pegvisomant prevents the actions of growth hormone, reducing the symptoms associated with acromegaly.

17. Which of the following statements concerning the pituitary gland is CORRECT?

ACTH is derived from the hypothalamus

Herring bodies store oxytocin and vasopressin

TSH is stored in the pars nervosa of the pituitary gland

Acidophils produce FSH and ACTH

Chromophils secrete oxytocin and vasopressin

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Explanation

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18. A 25-year-old male patient comes to a local clinic with the following complaints. He has to urinate frequently and he is constantly drinking water. A 24-urine collection is taken with the following findings. Urine volume is 6 liters per day and the specific gravity of the urine is 1.005 (normal range is 1.010-1.025). Your tentative diagnosis is diabetes insipidus. You administer intravenously an analogue of vasopressin and observe that the subsequent 24 hour urine collection is reduced to 3 liters per day. What is the most likely explanation for his polyuria?

Aquatrophs of the anterior pituitary are not being stimulated by vasopressin releasing hormone.

V1 receptors on epithelial cells of the collecting tubules and ducts are absent.

V2 receptors on epithelial cells of the collecting tubules and ducts are absent.

The most likely explanation for the patient's polyuria is that the magnocellular neurons of the paraventricular nucleus of the hypothalamus are not responding to an increase in whole body osmolarity and are not releasing vasopressin from the posterior pituitary. This is supported by the fact that administering an analogue of vasopressin reduced the urine volume, indicating that the patient's polyuria is due to a deficiency in vasopressin production or release.

Explanation

The most likely explanation for the patient's polyuria is that the magnocellular neurons of the paraventricular nucleus of the hypothalamus are not responding to an increase in whole body osmolarity and are not releasing vasopressin from the posterior pituitary. This is supported by the fact that administering an analogue of vasopressin reduced the urine volume, indicating that the patient's polyuria is due to a deficiency in vasopressin production or release.

19. By which of the following mechanisms does bromocriptine relieves symptoms of hyperprolactinemia in a patient with prolactin-secreting pituitary adenoma?

Blocking prolactin receptors

Blocking receptors for prolactin releasing hormone

A cytotoxic effect on pituitary adenoma cells

Activating receptors for prolactin-inhibiting hormone

Stimulating the breakdown of prolactin

Bromocriptine relieves symptoms of hyperprolactinemia in a patient with prolactin-secreting pituitary adenoma by activating receptors for prolactin-inhibiting hormone. This means that bromocriptine stimulates the receptors for dopamine, which is the prolactin-inhibiting hormone. By activating these receptors, bromocriptine reduces the secretion of prolactin from the pituitary gland, thereby relieving the symptoms of hyperprolactinemia.

Explanation

Bromocriptine relieves symptoms of hyperprolactinemia in a patient with prolactin-secreting pituitary adenoma by activating receptors for prolactin-inhibiting hormone. This means that bromocriptine stimulates the receptors for dopamine, which is the prolactin-inhibiting hormone. By activating these receptors, bromocriptine reduces the secretion of prolactin from the pituitary gland, thereby relieving the symptoms of hyperprolactinemia.

20. A 43-year old female patient comes to your office with the following symptoms: lethargy, postural hypotension, recent weight loss, and muscle weakness. Your tentative diagnosis is adrenal cortical dysfunction. You order a set of laboratory tests which come back with the following results: undetectable levels of plasma ACTH and very low plasma cortisol. In addition, you can demonstrate that exogenous CRF increases plasma cortisol. What is the most likely explanation for this patient's endocrine problem?

Disappearance of cortisol producing adrenal cortical cells

Nonfunctional corticotrophs of the anterior pituitary.

Nonfunctional corticotrophs of the posterior pituitary.

Insufficient production of CRF by hypothalamic neurons.

Absence of ACTH receptors on adrenal cortical cells.

The most likely explanation for this patient's endocrine problem is insufficient production of CRF by hypothalamic neurons. This is supported by the undetectable levels of plasma ACTH and very low plasma cortisol, as well as the fact that exogenous CRF increases plasma cortisol. These findings suggest a dysfunction in the hypothalamus, specifically in the production of CRF, which is necessary for the release of ACTH and subsequent cortisol production by the adrenal cortex.

Explanation

The most likely explanation for this patient's endocrine problem is insufficient production of CRF by hypothalamic neurons. This is supported by the undetectable levels of plasma ACTH and very low plasma cortisol, as well as the fact that exogenous CRF increases plasma cortisol. These findings suggest a dysfunction in the hypothalamus, specifically in the production of CRF, which is necessary for the release of ACTH and subsequent cortisol production by the adrenal cortex.

21. A 40-year-old man who presented with a history of violent attacks of watery diarrhea, cramping and paroxysmal vasomotor attacks (red to purple flushing of face and neck) is diagnosed with carcinoid syndrome. Which of the following drugs can most likely control his symptoms?

Sermorelin

Conivaptan

Pegvisomant

Octreotide

Somatrem

Desmopressin

Octreotide is the most likely drug to control the symptoms of carcinoid syndrome in this patient. Carcinoid syndrome is caused by the release of excessive amounts of serotonin and other vasoactive substances by carcinoid tumors. Octreotide is a synthetic analog of somatostatin, a hormone that inhibits the release of serotonin and other vasoactive substances. By administering octreotide, the symptoms of watery diarrhea, cramping, and paroxysmal vasomotor attacks can be controlled. Sermorelin, Conivaptan, Pegvisomant, Somatrem, and Desmopressin are not indicated for the treatment of carcinoid syndrome.

Explanation

Octreotide is the most likely drug to control the symptoms of carcinoid syndrome in this patient. Carcinoid syndrome is caused by the release of excessive amounts of serotonin and other vasoactive substances by carcinoid tumors. Octreotide is a synthetic analog of somatostatin, a hormone that inhibits the release of serotonin and other vasoactive substances. By administering octreotide, the symptoms of watery diarrhea, cramping, and paroxysmal vasomotor attacks can be controlled. Sermorelin, Conivaptan, Pegvisomant, Somatrem, and Desmopressin are not indicated for the treatment of carcinoid syndrome.