Q- Which one of the following medications stimulates muscarinic receptors in airways when inhaled?
A- Bethanechol
B- Carbachol
C- Methacholine
D- Pilocarpine
C- Methacholine- Methacholine is a muscarinic receptor agonist that stimulates muscarinic receptors in the airways when inhaled. It is primarily used in the methacholine challenge test to diagnose bronchial hyperresponsiveness in conditions like asthma. Inhalation of methacholine causes bronchoconstriction, and the degree of airway narrowing is measured to assess hyperreactivity.
Q- Which of the following characterizes syndrome of inappropriate antidiuretic hormone secretion?
A- Euvolemic hyponatremia with continued Na excretion
B- Hyperosmotic volume contraction
C- Recommended treatment is desmopressin acetate and hydration
D- Serum osmolality is greater than urine osmolality
A- Euvolemic hyponatremia with continued Na excretion- The Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) is characterized by excessive secretion of antidiuretic hormone (ADH), leading to increased water reabsorption in the kidneys. This causes dilutional hyponatremia with a euvolemic state (normal extracellular fluid volume) due to compensatory mechanisms such as increased natriuresis (sodium excretion).
Q- Which of the following organisms is responsible for antibiotic-associated colitis?
A- Clostridium difficile
B- Clostridium botulinum
C- Clostridium perfringens
D- Clostridium tetani
A- Clostridium difficile- Clostridium difficile (C. difficile) is the primary organism responsible for antibiotic-associated colitis (also known as C. difficile infection or CDI). Antibiotics can disrupt the normal gut microbiota, allowing C. difficile to overgrow and produce toxins (Toxin A and Toxin B) that damage the colonic mucosa, leading to diarrhea, abdominal pain, and potentially life-threatening complications like pseudomembranous colitis.
2 thoughts on “Repeated USMLE Questions- Pharmacology MCQs- 346”
Dear Dr. Nancy
This is a great question.
The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is best defined by:
-Hyponatremia with corresponding hypoosmolality
-Continued renal excretion of Na+
-Urine less than maximally dilute
-Absence of clinical evidence of volume depletion – Normal skin turgor, blood pressure within the reference range
-Absence of other causes of hyponatremia – Adrenal insufficiency (mineralocorticoid deficiency, glucocorticoid deficiency), hypothyroidism, cardiac failure, pituitary insufficiency, renal disease with salt wastage, hepatic disease, drugs that impair renal water excretion
Correction of hyponatremia is accomplished by fluid restriction
Thank you so much
Dear Dr Ray,
Can you please explain the SIADH question and why you choose euvolemic hyponatremia
Thanks
Dear Dr. Nancy
This is a great question.
The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is best defined by:
-Hyponatremia with corresponding hypoosmolality
-Continued renal excretion of Na+
-Urine less than maximally dilute
-Absence of clinical evidence of volume depletion – Normal skin turgor, blood pressure within the reference range
-Absence of other causes of hyponatremia – Adrenal insufficiency (mineralocorticoid deficiency, glucocorticoid deficiency), hypothyroidism, cardiac failure, pituitary insufficiency, renal disease with salt wastage, hepatic disease, drugs that impair renal water excretion
Correction of hyponatremia is accomplished by fluid restriction
Thank you so much
Dear Dr Ray,
Can you please explain the SIADH question and why you choose euvolemic hyponatremia
Thanks