HSC 4555 Exam 3 V2 | HSC 4555 Pathophysiology 1 | Actual Q&A with
Rationale (HSC4555 Exam 3) | University of Central Florida
1. A patient presents with polyuria, polydipsia, and a very low urine specific gravity. If the
cause is a deficiency in Antidiuretic Hormone (ADH) from the posterior pituitary, what is the
most likely diagnosis?
A. Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
B. Neurogenic Diabetes Insipidus
C. Psychogenic Polydipsia
D. Nephrogenic Diabetes Insipidus
Answer: B
Explanation: Neurogenic Diabetes Insipidus occurs when there is a central failure to
produce or release ADH from the hypothalamus or posterior pituitary. This lack of ADH
prevents the kidneys from reabsorbing water, leading to the excretion of large volumes of
dilute urine. Unlike the nephrogenic form, this condition typically responds well to
exogenous vasopressin administration.
2. Which electrolyte imbalance is the hallmark of the Syndrome of Inappropriate Antidiuretic
Hormone (SIADH)?
A. Hyperkalemia
B. Dilutional hyponatremia
C. Hypernatremia
D. Hypocalcemia
Answer: B
Explanation: SIADH is characterized by the excessive release of ADH, which causes the
kidneys to retain water despite normal or high fluid intake. This water retention leads to an
expansion of extracellular fluid volume and a subsequent dilution of serum sodium levels.
It is a classic example of hypotonic hyponatremia where the body holds onto too much free
water.
3. A 45-year-old female presents with exophthalmos, heat intolerance, and tachycardia.
Laboratory results show low TSH and high T3/T4 levels. What is the underlying
pathophysiology of Graves’ disease?
A. Destruction of thyroid follicular cells by T-cells
B. Autoantibodies (TSI) stimulating TSH receptors
,C. Pituitary adenoma secreting excess TSH
D. Iodine deficiency leading to goiter
Answer: B
Explanation: Graves’ disease is a type II hypersensitivity reaction where thyroid-
stimulating immunoglobulins (TSI) bind to and activate TSH receptors on the thyroid
gland. This continuous stimulation results in the overproduction of thyroid hormones and
thyroid gland hyperplasia. The exophthalmos is specifically caused by the infiltration of the
orbital soft tissues with inflammatory cells and edema.
4. What is the most common cause of primary hypothyroidism in iodine-sufficient regions like
the United States?
A. Pituitary failure
B. Hashimoto Thyroiditis
C. Graves’ disease
D. Subacute thyroiditis
Answer: B
Explanation: Hashimoto Thyroiditis is an autoimmune condition characterized by the
destruction of the thyroid gland by lymphocytes and antithyroid antibodies. It is the
leading cause of primary hypothyroidism in the United States, typically resulting in a firm,
painless goiter. Over time, the destruction leads to a permanent decrease in T3 and T4
levels with a compensatory rise in TSH.
5. In Cushing’s Disease, the excess production of cortisol is specifically caused by which of the
following?
A. Exogenous steroid use
B. Small cell lung carcinoma
C. An adrenal cortex tumor
D. An ACTH-secreting pituitary adenoma
Answer: D
Explanation: Cushing’s disease refers specifically to hypercortisolism caused by excessive
ACTH secretion from a pituitary adenoma. This distinguishes it from ‘Cushing’s syndrome,’
which is a broader term for any condition resulting in elevated cortisol levels. The chronic
exposure to high cortisol leads to classic signs like moon facies, buffalo hump, and central
obesity.
, 6. Which clinical manifestation is characteristic of Addison’s Disease (Primary Adrenocortical
Insufficiency)?
A. Hypernatremia
B. Hypertension
C. Hyperglycemia
D. Hyperpigmentation of the skin
Answer: D
Explanation: Addison’s disease involves the destruction of the adrenal cortex, leading to a
deficiency in cortisol and aldosterone. The lack of cortisol feedback causes the pituitary to
produce high levels of ACTH and MSH (Melanocyte-Stimulating Hormone), resulting in
bronze-colored skin pigmentation. Patients also suffer from hypotension and hypoglycemia
due to the loss of these vital metabolic hormones.
7. A patient with a pheochromocytoma will most likely experience which symptom due to
excessive catecholamine secretion?
A. Bradycardia
B. Episodic severe hypertension
C. Weight gain
D. Hypotension
Answer: B
Explanation: A pheochromocytoma is a rare tumor of the adrenal medulla that secretes
massive amounts of epinephrine and norepinephrine. The resulting sympathetic
stimulation causes episodes of headache, diaphoresis, and severe hypertension. If left
untreated, the chronic stress on the cardiovascular system can lead to stroke or heart
failure.
8. What is the primary pathophysiological mechanism behind Type 1 Diabetes Mellitus?
A. Insulin resistance in peripheral tissues
B. Excessive glucagon secretion
C. Downregulation of insulin receptors
D. Autoimmune destruction of pancreatic beta cells
Answer: D
Explanation: Type 1 Diabetes Mellitus is characterized by a nearly absolute deficiency of
insulin caused by the T-cell-mediated autoimmune destruction of beta cells in the
pancreatic islets. Without insulin, glucose cannot enter cells for fuel, leading to
Rationale (HSC4555 Exam 3) | University of Central Florida
1. A patient presents with polyuria, polydipsia, and a very low urine specific gravity. If the
cause is a deficiency in Antidiuretic Hormone (ADH) from the posterior pituitary, what is the
most likely diagnosis?
A. Syndrome of Inappropriate Antidiuretic Hormone (SIADH)
B. Neurogenic Diabetes Insipidus
C. Psychogenic Polydipsia
D. Nephrogenic Diabetes Insipidus
Answer: B
Explanation: Neurogenic Diabetes Insipidus occurs when there is a central failure to
produce or release ADH from the hypothalamus or posterior pituitary. This lack of ADH
prevents the kidneys from reabsorbing water, leading to the excretion of large volumes of
dilute urine. Unlike the nephrogenic form, this condition typically responds well to
exogenous vasopressin administration.
2. Which electrolyte imbalance is the hallmark of the Syndrome of Inappropriate Antidiuretic
Hormone (SIADH)?
A. Hyperkalemia
B. Dilutional hyponatremia
C. Hypernatremia
D. Hypocalcemia
Answer: B
Explanation: SIADH is characterized by the excessive release of ADH, which causes the
kidneys to retain water despite normal or high fluid intake. This water retention leads to an
expansion of extracellular fluid volume and a subsequent dilution of serum sodium levels.
It is a classic example of hypotonic hyponatremia where the body holds onto too much free
water.
3. A 45-year-old female presents with exophthalmos, heat intolerance, and tachycardia.
Laboratory results show low TSH and high T3/T4 levels. What is the underlying
pathophysiology of Graves’ disease?
A. Destruction of thyroid follicular cells by T-cells
B. Autoantibodies (TSI) stimulating TSH receptors
,C. Pituitary adenoma secreting excess TSH
D. Iodine deficiency leading to goiter
Answer: B
Explanation: Graves’ disease is a type II hypersensitivity reaction where thyroid-
stimulating immunoglobulins (TSI) bind to and activate TSH receptors on the thyroid
gland. This continuous stimulation results in the overproduction of thyroid hormones and
thyroid gland hyperplasia. The exophthalmos is specifically caused by the infiltration of the
orbital soft tissues with inflammatory cells and edema.
4. What is the most common cause of primary hypothyroidism in iodine-sufficient regions like
the United States?
A. Pituitary failure
B. Hashimoto Thyroiditis
C. Graves’ disease
D. Subacute thyroiditis
Answer: B
Explanation: Hashimoto Thyroiditis is an autoimmune condition characterized by the
destruction of the thyroid gland by lymphocytes and antithyroid antibodies. It is the
leading cause of primary hypothyroidism in the United States, typically resulting in a firm,
painless goiter. Over time, the destruction leads to a permanent decrease in T3 and T4
levels with a compensatory rise in TSH.
5. In Cushing’s Disease, the excess production of cortisol is specifically caused by which of the
following?
A. Exogenous steroid use
B. Small cell lung carcinoma
C. An adrenal cortex tumor
D. An ACTH-secreting pituitary adenoma
Answer: D
Explanation: Cushing’s disease refers specifically to hypercortisolism caused by excessive
ACTH secretion from a pituitary adenoma. This distinguishes it from ‘Cushing’s syndrome,’
which is a broader term for any condition resulting in elevated cortisol levels. The chronic
exposure to high cortisol leads to classic signs like moon facies, buffalo hump, and central
obesity.
, 6. Which clinical manifestation is characteristic of Addison’s Disease (Primary Adrenocortical
Insufficiency)?
A. Hypernatremia
B. Hypertension
C. Hyperglycemia
D. Hyperpigmentation of the skin
Answer: D
Explanation: Addison’s disease involves the destruction of the adrenal cortex, leading to a
deficiency in cortisol and aldosterone. The lack of cortisol feedback causes the pituitary to
produce high levels of ACTH and MSH (Melanocyte-Stimulating Hormone), resulting in
bronze-colored skin pigmentation. Patients also suffer from hypotension and hypoglycemia
due to the loss of these vital metabolic hormones.
7. A patient with a pheochromocytoma will most likely experience which symptom due to
excessive catecholamine secretion?
A. Bradycardia
B. Episodic severe hypertension
C. Weight gain
D. Hypotension
Answer: B
Explanation: A pheochromocytoma is a rare tumor of the adrenal medulla that secretes
massive amounts of epinephrine and norepinephrine. The resulting sympathetic
stimulation causes episodes of headache, diaphoresis, and severe hypertension. If left
untreated, the chronic stress on the cardiovascular system can lead to stroke or heart
failure.
8. What is the primary pathophysiological mechanism behind Type 1 Diabetes Mellitus?
A. Insulin resistance in peripheral tissues
B. Excessive glucagon secretion
C. Downregulation of insulin receptors
D. Autoimmune destruction of pancreatic beta cells
Answer: D
Explanation: Type 1 Diabetes Mellitus is characterized by a nearly absolute deficiency of
insulin caused by the T-cell-mediated autoimmune destruction of beta cells in the
pancreatic islets. Without insulin, glucose cannot enter cells for fuel, leading to
