NBME 25 Exam Questions and Answers
Patient had anaphylaxis following the transfusion of fresh frozen plasma. What is the
genetic deficiency? - Answers -IgA deficiency. Patient with this disease may have
preformed antibodies against IgA
How does sitagliptin work? - Answers -It is a competitive inhibitor of dipeptidyl
peptidase-4 (DPP4). It prevents breakdown of GI incretins (ex: glucagon-like peptide,
GLP-1) and promote endogenous release of insulin.
** DPP4 inhibitor increases endogenous insulin
What are acoustic neuromas? - Answers -Vestibular schwannoma
Benign tumors of Schwann cells that arise from the vestibulocochlear nerve (CN VIII).
How does acoustic neuromas cause symptoms? - Answers -Lesions of CN VIII leads to
ipsilateral hearing loss and positional dizziness
Compression of the cerebellar peduncles leads to ipsilateral dysmetria
What is the classic presentation of pyloric stenosis? - Answers -Male infant 3-6 weeks
of age with repeated vomiting after feeds, dehydration, and hypochloremic, hypokalemic
metabolic alkalosis
Explain the electrolyte and metabolic derangement seen with pyloric stenosis - Answers
-Vomiting -> Hypochloremia
Hypovolemia + excess bicarb -> RAAS activation -> increase renal tubule bicarb
reabsorption -> Metabolic alkalosis
Metabolic alkalosis + hypovolemia + increased aldosterone -> renal potassium excretion
-> hypokalemia
How does hypokalemia worsens metabolic alkalosis? - Answers -Hypokalemia further
worsens metabolic alkalosis via trans-cellular exchange or extracellular sodium and
protons in for potassium ions
IV drug user presents with tricuspid regurgitation and signs and symptoms of right-sided
heart failure. Diagnosis? - Answers -Tricuspid valve endocarditis
, Tricuspid valve endocarditis is associated with what organisms? - Answers -Staph
Aureus
Pseudomonas
Candida
Describe the sound and location of tricuspid regurgitation murmur? - Answers -
Holosystolic murmur best heard at the left lower sternal border
What is the treatment for herpes simplex virus and varicella zoster virus? - Answers -
Guanosine analogs such as acyclovir, famciclovir, valacyclovir
How does acyclovir, famciclovir, and valacyclovir work? - Answers -Inhibits viral DNA
polymerase
First, they are phosphorylated by the viral thymidine kinase. Then, they are able to
inhibit viral DNA polymerase by terminating the nascent DNA chain during replication.
How does HSV or VZV confer resistance to guanosine analogs? - Answers -Mutation in
the viral thymidine kinase enzyme
Guanosine analog would not be phosphorylated and thus cannot inhibit viral DNA
polymerase.
How does lithium carbonate cause nephrogenic diabetes insipidus? - Answers -Lithium
concentrates in the renal collecting duct, which then interferes with the signaling
pathway of ADH
Inhibits c-AMP-mediated pathway in the renal collecting duct
What is the pathophysiology of nephrogenic diabetes insipidus? - Answers -Renal
collecting duct becomes insensitive to ADH.
How does antidiuretic hormone work? - Answers -ADH is released by the posterior
pituitary in response to hypovolemia.
It increases aquaporin channels in the cortical collecting duct via a c-AMP mediated
pathway. This then reclaims free water -> increase volume and decrease serum
osmolality.
What are lab findings associated with nephrogenic diabetes insipidus? - Answers -
Increased serum osmolarity
Hypernatremia
Inappropritely dilute urine
How can nephrogenic DI be differentiated from central DI? - Answers -Desmopressin
(ADH analog)
Patient had anaphylaxis following the transfusion of fresh frozen plasma. What is the
genetic deficiency? - Answers -IgA deficiency. Patient with this disease may have
preformed antibodies against IgA
How does sitagliptin work? - Answers -It is a competitive inhibitor of dipeptidyl
peptidase-4 (DPP4). It prevents breakdown of GI incretins (ex: glucagon-like peptide,
GLP-1) and promote endogenous release of insulin.
** DPP4 inhibitor increases endogenous insulin
What are acoustic neuromas? - Answers -Vestibular schwannoma
Benign tumors of Schwann cells that arise from the vestibulocochlear nerve (CN VIII).
How does acoustic neuromas cause symptoms? - Answers -Lesions of CN VIII leads to
ipsilateral hearing loss and positional dizziness
Compression of the cerebellar peduncles leads to ipsilateral dysmetria
What is the classic presentation of pyloric stenosis? - Answers -Male infant 3-6 weeks
of age with repeated vomiting after feeds, dehydration, and hypochloremic, hypokalemic
metabolic alkalosis
Explain the electrolyte and metabolic derangement seen with pyloric stenosis - Answers
-Vomiting -> Hypochloremia
Hypovolemia + excess bicarb -> RAAS activation -> increase renal tubule bicarb
reabsorption -> Metabolic alkalosis
Metabolic alkalosis + hypovolemia + increased aldosterone -> renal potassium excretion
-> hypokalemia
How does hypokalemia worsens metabolic alkalosis? - Answers -Hypokalemia further
worsens metabolic alkalosis via trans-cellular exchange or extracellular sodium and
protons in for potassium ions
IV drug user presents with tricuspid regurgitation and signs and symptoms of right-sided
heart failure. Diagnosis? - Answers -Tricuspid valve endocarditis
, Tricuspid valve endocarditis is associated with what organisms? - Answers -Staph
Aureus
Pseudomonas
Candida
Describe the sound and location of tricuspid regurgitation murmur? - Answers -
Holosystolic murmur best heard at the left lower sternal border
What is the treatment for herpes simplex virus and varicella zoster virus? - Answers -
Guanosine analogs such as acyclovir, famciclovir, valacyclovir
How does acyclovir, famciclovir, and valacyclovir work? - Answers -Inhibits viral DNA
polymerase
First, they are phosphorylated by the viral thymidine kinase. Then, they are able to
inhibit viral DNA polymerase by terminating the nascent DNA chain during replication.
How does HSV or VZV confer resistance to guanosine analogs? - Answers -Mutation in
the viral thymidine kinase enzyme
Guanosine analog would not be phosphorylated and thus cannot inhibit viral DNA
polymerase.
How does lithium carbonate cause nephrogenic diabetes insipidus? - Answers -Lithium
concentrates in the renal collecting duct, which then interferes with the signaling
pathway of ADH
Inhibits c-AMP-mediated pathway in the renal collecting duct
What is the pathophysiology of nephrogenic diabetes insipidus? - Answers -Renal
collecting duct becomes insensitive to ADH.
How does antidiuretic hormone work? - Answers -ADH is released by the posterior
pituitary in response to hypovolemia.
It increases aquaporin channels in the cortical collecting duct via a c-AMP mediated
pathway. This then reclaims free water -> increase volume and decrease serum
osmolality.
What are lab findings associated with nephrogenic diabetes insipidus? - Answers -
Increased serum osmolarity
Hypernatremia
Inappropritely dilute urine
How can nephrogenic DI be differentiated from central DI? - Answers -Desmopressin
(ADH analog)
