NU606 | NU606 Advanced Pathophysiology Exam 4
Version 2 | Questions with Correct Answers and
Expert Explanation for Each Question | Regis
1. A patient with central diabetes insipidus (DI) is likely to exhibit which of the
following clinical manifestations?
A. Concentrated urine and hyponatremia
B. High urine specific gravity and hypertension
C. Water retention and edema
D. Polyuria, polydipsia, and low urine specific gravity
Correct Answer: D
Expert Explanation: Central diabetes insipidus is characterized by a deficiency in
antidiuretic hormone (ADH), which leads to the inability of the kidneys to
concentrate urine. This results in the excretion of large volumes of dilute urine,
typically with a specific gravity below 1.005. Patients experience compensatory
polydipsia due to the increased serum osmolality and dehydration caused by
massive fluid loss.
2. In the pathophysiology of Syndrome of Inappropriate Antidiuretic Hormone
(SIADH), what is the primary cause of hyponatremia?
A. Excessive sodium loss in the stool
,B. Hyperaldosteronism
C. Decreased sodium intake
D. Dilution of serum sodium due to excessive water reabsorption
Correct Answer: D
Expert Explanation: SIADH involves the excessive release of ADH regardless of
serum osmolality, which causes the kidneys to reabsorb water in the collecting
ducts. This excess water retention expands the extracellular fluid volume and
dilutes the serum sodium concentration, leading to dilutional hyponatremia. Unlike
conditions involving true sodium loss, the total body sodium may be normal, but it is
disproportionately low relative to the water volume.
3. Which mechanism is responsible for the development of exophthalmos in Graves’
disease?
A. Increased intraocular pressure from aqueous humor buildup
B. Accumulation of hyaluronic acid and inflammation behind the eyes
C. Decreased production of thyroid-stimulating hormone
D. Atrophy of the extraocular muscles
Correct Answer: B
,Expert Explanation: Graves’ ophthalmopathy is an autoimmune process where
antibodies target the fibroblasts in the extraocular muscles and orbital fat. This
causes an accumulation of glycosaminoglycans like hyaluronic acid, which leads to
swelling, inflammation, and edema within the orbital cavity. The resulting pressure
pushes the eyeball forward, creating the characteristic bulging appearance known
as exophthalmos.
4. A patient presents with a ‘moon face,’ buffalo hump, and truncal obesity. Which of
the following conditions is most consistent with these symptoms?
A. Cushing syndrome
B. Hypothyroidism
C. Addison’s disease
D. Pheochromocytoma
Correct Answer: A
Expert Explanation: Cushing syndrome results from chronic exposure to excessive
levels of glucocorticoids, such as cortisol. This hormone excess causes a
redistribution of adipose tissue to the face (moon face), the cervicodorsal area
(buffalo hump), and the abdomen (truncal obesity). Additionally, high cortisol levels
lead to protein wasting and skin thinning, which explains the presence of purple
striae and muscle weakness.
, 5. Which laboratory finding is diagnostic for Addison’s disease (primary adrenal
insufficiency)?
A. Hypernatremia and hypokalemia
B. Hyperglycemia and high cortisol
C. Low ACTH and low serum potassium
D. Low serum cortisol and elevated ACTH levels
Correct Answer: D
Expert Explanation: Primary adrenal insufficiency, or Addison’s disease, occurs
when the adrenal cortex is damaged and cannot produce sufficient cortisol or
aldosterone. In response to low cortisol, the pituitary gland increases the secretion
of adrenocorticotropic hormone (ACTH) via a negative feedback loop. Therefore, the
hallmark of primary insufficiency is low cortisol paired with high ACTH, often
accompanied by electrolyte imbalances like hyperkalemia.
6. What is the underlying pathophysiology of Type 1 Diabetes Mellitus?
A. Autoimmune destruction of pancreatic beta cells
B. Insulin resistance in peripheral tissues
C. Excessive glucagon secretion from alpha cells
D. Downregulation of insulin receptors
Version 2 | Questions with Correct Answers and
Expert Explanation for Each Question | Regis
1. A patient with central diabetes insipidus (DI) is likely to exhibit which of the
following clinical manifestations?
A. Concentrated urine and hyponatremia
B. High urine specific gravity and hypertension
C. Water retention and edema
D. Polyuria, polydipsia, and low urine specific gravity
Correct Answer: D
Expert Explanation: Central diabetes insipidus is characterized by a deficiency in
antidiuretic hormone (ADH), which leads to the inability of the kidneys to
concentrate urine. This results in the excretion of large volumes of dilute urine,
typically with a specific gravity below 1.005. Patients experience compensatory
polydipsia due to the increased serum osmolality and dehydration caused by
massive fluid loss.
2. In the pathophysiology of Syndrome of Inappropriate Antidiuretic Hormone
(SIADH), what is the primary cause of hyponatremia?
A. Excessive sodium loss in the stool
,B. Hyperaldosteronism
C. Decreased sodium intake
D. Dilution of serum sodium due to excessive water reabsorption
Correct Answer: D
Expert Explanation: SIADH involves the excessive release of ADH regardless of
serum osmolality, which causes the kidneys to reabsorb water in the collecting
ducts. This excess water retention expands the extracellular fluid volume and
dilutes the serum sodium concentration, leading to dilutional hyponatremia. Unlike
conditions involving true sodium loss, the total body sodium may be normal, but it is
disproportionately low relative to the water volume.
3. Which mechanism is responsible for the development of exophthalmos in Graves’
disease?
A. Increased intraocular pressure from aqueous humor buildup
B. Accumulation of hyaluronic acid and inflammation behind the eyes
C. Decreased production of thyroid-stimulating hormone
D. Atrophy of the extraocular muscles
Correct Answer: B
,Expert Explanation: Graves’ ophthalmopathy is an autoimmune process where
antibodies target the fibroblasts in the extraocular muscles and orbital fat. This
causes an accumulation of glycosaminoglycans like hyaluronic acid, which leads to
swelling, inflammation, and edema within the orbital cavity. The resulting pressure
pushes the eyeball forward, creating the characteristic bulging appearance known
as exophthalmos.
4. A patient presents with a ‘moon face,’ buffalo hump, and truncal obesity. Which of
the following conditions is most consistent with these symptoms?
A. Cushing syndrome
B. Hypothyroidism
C. Addison’s disease
D. Pheochromocytoma
Correct Answer: A
Expert Explanation: Cushing syndrome results from chronic exposure to excessive
levels of glucocorticoids, such as cortisol. This hormone excess causes a
redistribution of adipose tissue to the face (moon face), the cervicodorsal area
(buffalo hump), and the abdomen (truncal obesity). Additionally, high cortisol levels
lead to protein wasting and skin thinning, which explains the presence of purple
striae and muscle weakness.
, 5. Which laboratory finding is diagnostic for Addison’s disease (primary adrenal
insufficiency)?
A. Hypernatremia and hypokalemia
B. Hyperglycemia and high cortisol
C. Low ACTH and low serum potassium
D. Low serum cortisol and elevated ACTH levels
Correct Answer: D
Expert Explanation: Primary adrenal insufficiency, or Addison’s disease, occurs
when the adrenal cortex is damaged and cannot produce sufficient cortisol or
aldosterone. In response to low cortisol, the pituitary gland increases the secretion
of adrenocorticotropic hormone (ACTH) via a negative feedback loop. Therefore, the
hallmark of primary insufficiency is low cortisol paired with high ACTH, often
accompanied by electrolyte imbalances like hyperkalemia.
6. What is the underlying pathophysiology of Type 1 Diabetes Mellitus?
A. Autoimmune destruction of pancreatic beta cells
B. Insulin resistance in peripheral tissues
C. Excessive glucagon secretion from alpha cells
D. Downregulation of insulin receptors
