NBME 25
1. Patient had anaphylaxis following IgA deficiency. Patient with this disease may have pre-
the transfusion of fresh frozen plas- formed antibodies against IgA
ma. What is the genetic deficiency?
2. How does sitagliptin work? It is a competitive inhibitor of dipeptidyl peptidase-4
(DPP4). It prevents breakdown of GI incretins (ex:
glucagon-like peptide, GLP-1) and promote endoge-
nous release of insulin.
** DPP4 inhibitor increases endogenous insulin
3. What are acoustic neuromas? Vestibular schwannoma
Benign tumors of Schwann cells that arise from the
vestibulocochlear nerve (CN VIII).
4. How does acoustic neuromas cause Lesions of CN VIII leads to ipsilateral hearing loss and
symptoms? positional dizziness
Compression of the cerebellar peduncles leads to ip-
silateral dysmetria
5. What is the classic presentation of Male infant 3-6 weeks of age with repeated vomit-
pyloric stenosis? ing after feeds, dehydration, and hypochloremic, hy-
pokalemic metabolic alkalosis
6. Vomiting -> Hypochloremia
, NBME 25
Explain the electrolyte and meta- Hypovolemia + excess bicarb -> RAAS activation -> in-
bolic derangement seen with py- crease renal tubule bicarb reabsorption -> Metabolic
loric stenosis alkalosis
Metabolic alkalosis + hypovolemia + increased aldos-
terone -> renal potassium excretion -> hypokalemia
7. How does hypokalemia worsens Hypokalemia further worsens metabolic alkalosis via
metabolic alkalosis? trans-cellular exchange or extracellular sodium and
protons in for potassium ions
8. IV drug user presents with tricuspid Tricuspid valve endocarditis
regurgitation and signs and symp-
toms of right-sided heart failure. Di-
agnosis?
9. Tricuspid valve endocarditis is asso- Staph Aureus
ciated with what organisms? Pseudomonas
Candida
10. Describe the sound and location of Holosystolic murmur best heard at the left lower ster-
tricuspid regurgitation murmur? nal border
11. What is the treatment for herpes Guanosine analogs such as acyclovir, famciclovir, vala-
simplex virus and varicella zoster cyclovir
virus?
12. How does acyclovir, famciclovir, and Inhibits viral DNA polymerase
valacyclovir work?
First, they are phosphorylated by the viral thymidine
kinase. Then, they are able to inhibit viral DNA poly-
merase by terminating the nascent DNA chain during
replication.
, NBME 25
13. How does HSV or VZV confer resis- Mutation in the viral thymidine kinase enzyme
tance to guanosine analogs?
Guanosine analog would not be phosphorylated and
thus cannot inhibit viral DNA polymerase.
14. How does lithium carbonate cause Lithium concentrates in the renal collecting duct,
nephrogenic diabetes insipidus? which then interferes with the signaling pathway of
ADH
Inhibits c-AMP-mediated pathway in the renal collect-
ing duct
15. What is the pathophysiology of Renal collecting duct becomes insensitive to ADH.
nephrogenic diabetes insipidus?
16. How does antidiuretic hormone ADH is released by the posterior pituitary in response
work? to hypovolemia.
It increases aquaporin channels in the cortical col-
lecting duct via a c-AMP mediated pathway. This then
reclaims free water -> increase volume and decrease
serum osmolality.
17. What are lab findings associat- Increased serum osmolarity
ed with nephrogenic diabetes in- Hypernatremia
sipidus? Inappropritely dilute urine
18. How can nephrogenic DI be differ- Desmopressin (ADH analog)
entiated from central DI?
Nephorgenic DI - No response
Central DI - decrease urine output and serum osmo-
larity
1. Patient had anaphylaxis following IgA deficiency. Patient with this disease may have pre-
the transfusion of fresh frozen plas- formed antibodies against IgA
ma. What is the genetic deficiency?
2. How does sitagliptin work? It is a competitive inhibitor of dipeptidyl peptidase-4
(DPP4). It prevents breakdown of GI incretins (ex:
glucagon-like peptide, GLP-1) and promote endoge-
nous release of insulin.
** DPP4 inhibitor increases endogenous insulin
3. What are acoustic neuromas? Vestibular schwannoma
Benign tumors of Schwann cells that arise from the
vestibulocochlear nerve (CN VIII).
4. How does acoustic neuromas cause Lesions of CN VIII leads to ipsilateral hearing loss and
symptoms? positional dizziness
Compression of the cerebellar peduncles leads to ip-
silateral dysmetria
5. What is the classic presentation of Male infant 3-6 weeks of age with repeated vomit-
pyloric stenosis? ing after feeds, dehydration, and hypochloremic, hy-
pokalemic metabolic alkalosis
6. Vomiting -> Hypochloremia
, NBME 25
Explain the electrolyte and meta- Hypovolemia + excess bicarb -> RAAS activation -> in-
bolic derangement seen with py- crease renal tubule bicarb reabsorption -> Metabolic
loric stenosis alkalosis
Metabolic alkalosis + hypovolemia + increased aldos-
terone -> renal potassium excretion -> hypokalemia
7. How does hypokalemia worsens Hypokalemia further worsens metabolic alkalosis via
metabolic alkalosis? trans-cellular exchange or extracellular sodium and
protons in for potassium ions
8. IV drug user presents with tricuspid Tricuspid valve endocarditis
regurgitation and signs and symp-
toms of right-sided heart failure. Di-
agnosis?
9. Tricuspid valve endocarditis is asso- Staph Aureus
ciated with what organisms? Pseudomonas
Candida
10. Describe the sound and location of Holosystolic murmur best heard at the left lower ster-
tricuspid regurgitation murmur? nal border
11. What is the treatment for herpes Guanosine analogs such as acyclovir, famciclovir, vala-
simplex virus and varicella zoster cyclovir
virus?
12. How does acyclovir, famciclovir, and Inhibits viral DNA polymerase
valacyclovir work?
First, they are phosphorylated by the viral thymidine
kinase. Then, they are able to inhibit viral DNA poly-
merase by terminating the nascent DNA chain during
replication.
, NBME 25
13. How does HSV or VZV confer resis- Mutation in the viral thymidine kinase enzyme
tance to guanosine analogs?
Guanosine analog would not be phosphorylated and
thus cannot inhibit viral DNA polymerase.
14. How does lithium carbonate cause Lithium concentrates in the renal collecting duct,
nephrogenic diabetes insipidus? which then interferes with the signaling pathway of
ADH
Inhibits c-AMP-mediated pathway in the renal collect-
ing duct
15. What is the pathophysiology of Renal collecting duct becomes insensitive to ADH.
nephrogenic diabetes insipidus?
16. How does antidiuretic hormone ADH is released by the posterior pituitary in response
work? to hypovolemia.
It increases aquaporin channels in the cortical col-
lecting duct via a c-AMP mediated pathway. This then
reclaims free water -> increase volume and decrease
serum osmolality.
17. What are lab findings associat- Increased serum osmolarity
ed with nephrogenic diabetes in- Hypernatremia
sipidus? Inappropritely dilute urine
18. How can nephrogenic DI be differ- Desmopressin (ADH analog)
entiated from central DI?
Nephorgenic DI - No response
Central DI - decrease urine output and serum osmo-
larity
