Page 1 of 391
NBME 26 EXAM ALL 200 QUESTIONS AND CORRECT
ANSWERS LATEST UPDATE THIS YEAR NEW!!
QUESTION: 1
----------
Exam Section 1: Item 2 of 50
National, Board of Medical Examiners
Comprehensive Basic Science Self-Assessment
5. A 65-year-old woman has ascites. Which of the following additional findings indicates a
diagnosis of constrictive pericarditis rather than cirrhosis?
O A) Edema of the lower extremities
B) Esophageal varices
C) Hypoalbuminemia
D) Hyponatremia
E) Increased jugular venous pressure
F) Splenomegaly - ANSWER-E.
Increased jugular venous pressure (JVP) is an expected finding in constrictive pericarditis (CP)
and would not be found in patients with volume overload secondary to cirrhosis. CP describes a
pathologic state whereby the pericardium, which encases the entirety of
1
,Page 2 of 391
the heart and the origins of the great vessels, loses its elasticity. This can occur in patients with
viral infections, connective tissue disease, tuberculosis, or as a result of cardiac surgery or
radiation. During the normal cardiac cycle, increased venous return to the
right atrium (RA) and right ventricle (RV) during inspiration leads to transient expansion of the
RV with slight bowing of the interventricular septum into the left ventricle (LV). This increased
RV preload does not impair LV filling as the pericardial sac expands to
accommodate the increased RV volume. In constrictive pericarditis, the pericardial sac loses its
elasticity. When venous return to the right heart increases, the pericardial sac is unable to
expand, which exacerbates movement of the interventricular septum into the
LV. This impairs diastolic filling of the LV and reduces cardiac output. LV diastolic filling is
further reduced by a reduction in preload from the pulmonary veins. The constricted
pericardium does not respond to normal changes in intrathoracic pressure during
inspiration, but the pulmonary venous system, which lies outside of the pericardium,
experiences a normal drop in pressure during inspiration. This difference creates an abnormal
pressure gradient that reduces LV preload and leads to reduced cardiac output. The
RV and LV develop interventricular dependence whereby increased pressure in each ventricle
begins to affect the other ventricle. CP ultimately results in equalization of pressures in all four
chambers, with clinical evidence of right heart failure exhib
2
----------
Exam Section 1: Item 3 of 50
National, Board of Medical Examiners
Comprehensive Basic Science Self-Assessment
2
,Page 3 of 391
2. Free purine and pyrimidine bases are reutilized in normal metabolism. In children with Lesch-
Nyhan syndrome who have intellectual disability, poor muscle coordination, and self-mutilation
tendencies, there is a defect in the salvage of which of the following
pairs of bases?
A) Adenine and thymine
B) Guanine and hypoxanthine
C) Guanine and uric acid
D) Uracil and cytosine
E) Xanthine and hypoxanthine - ANSWER-B.
Lesch-Nyhan syndrome presents with intellectual disability, aggressive behavior, self-
mutilation, gout, and dystonia. The disorder is due to inactivating mutations of hypoxanthine-
guanine phosphoribosyltransferase (HGPRT), a key enzyme in the purine salvage
pathway, and is inherited in an X-linked recessive fashion. HGPRT catalyzes the conversion of
guanine to guanosine monophosphate and hypoxanthine to inosine monophosphate. Patients
with deficient activity of HGPRT are unable to salvage guanine and
hypoxanthine and develop resultant increased levels of xanthine and uric acid. Hyperuricemia
in Lesch-Nyhan syndrome is treated with xanthine oxidase inhibitors, such as allopurinol or
febuxostat, in order to reduce the synthesis of uric acid.
Incorrect Answers: A, C, D and E.
Adenine and thymine (Choice A) are purine and pyrimidine bases, respectively. Purine and
pyrimidine salvage are handled through two distinct pathways that are not commonly involved
in a single disease process.
3
, Page 4 of 391
Guanine and uric acid (Choice C) accumulation may occur as part of Lesch-Nyhan syndrome,
however, the accumulation of uric acid is also secondary to accumulation of hypoxanthine.
Choice B more accurately describes defective salvage of guanine and
hypoxanthine as the fundamental effect of HGPRT dysfunction. The accumulation of uric acid is
secondary.
Uracil and cytosine (Choice D) are pyrimidine nucleotides. Pyrimidine salvage is not affected by
mutations of HGPRT.
Defects of xanthine and hypoxanthine (Choice E) metabolism may result from defects in HGPRT.
However, HGPRT dysfunction results in impaired hypoxanthine salvage with resultant excessive
production of xanthine, rather than impaired xanthine salvage.
Educational Objective: Lesch-Nyhan syndrome presents with intellectual disability, aggressive
behavior, self-mutilation, gout, and dyst
QUESTION: 2
----------
Exam Section 1: Item 3 of 50
National Board of Medical Examiners
Comprehensive Basic Science Self-Assessment
3. A 42-year-old man is struck by a motor vehicle. His only injury is a closed fracture of the
proximal tibia. Initial neurovascular examination shows no deficits. Twenty-four hours later, he
has increased leg pain and paresthesias in the dorsal space between his
4
NBME 26 EXAM ALL 200 QUESTIONS AND CORRECT
ANSWERS LATEST UPDATE THIS YEAR NEW!!
QUESTION: 1
----------
Exam Section 1: Item 2 of 50
National, Board of Medical Examiners
Comprehensive Basic Science Self-Assessment
5. A 65-year-old woman has ascites. Which of the following additional findings indicates a
diagnosis of constrictive pericarditis rather than cirrhosis?
O A) Edema of the lower extremities
B) Esophageal varices
C) Hypoalbuminemia
D) Hyponatremia
E) Increased jugular venous pressure
F) Splenomegaly - ANSWER-E.
Increased jugular venous pressure (JVP) is an expected finding in constrictive pericarditis (CP)
and would not be found in patients with volume overload secondary to cirrhosis. CP describes a
pathologic state whereby the pericardium, which encases the entirety of
1
,Page 2 of 391
the heart and the origins of the great vessels, loses its elasticity. This can occur in patients with
viral infections, connective tissue disease, tuberculosis, or as a result of cardiac surgery or
radiation. During the normal cardiac cycle, increased venous return to the
right atrium (RA) and right ventricle (RV) during inspiration leads to transient expansion of the
RV with slight bowing of the interventricular septum into the left ventricle (LV). This increased
RV preload does not impair LV filling as the pericardial sac expands to
accommodate the increased RV volume. In constrictive pericarditis, the pericardial sac loses its
elasticity. When venous return to the right heart increases, the pericardial sac is unable to
expand, which exacerbates movement of the interventricular septum into the
LV. This impairs diastolic filling of the LV and reduces cardiac output. LV diastolic filling is
further reduced by a reduction in preload from the pulmonary veins. The constricted
pericardium does not respond to normal changes in intrathoracic pressure during
inspiration, but the pulmonary venous system, which lies outside of the pericardium,
experiences a normal drop in pressure during inspiration. This difference creates an abnormal
pressure gradient that reduces LV preload and leads to reduced cardiac output. The
RV and LV develop interventricular dependence whereby increased pressure in each ventricle
begins to affect the other ventricle. CP ultimately results in equalization of pressures in all four
chambers, with clinical evidence of right heart failure exhib
2
----------
Exam Section 1: Item 3 of 50
National, Board of Medical Examiners
Comprehensive Basic Science Self-Assessment
2
,Page 3 of 391
2. Free purine and pyrimidine bases are reutilized in normal metabolism. In children with Lesch-
Nyhan syndrome who have intellectual disability, poor muscle coordination, and self-mutilation
tendencies, there is a defect in the salvage of which of the following
pairs of bases?
A) Adenine and thymine
B) Guanine and hypoxanthine
C) Guanine and uric acid
D) Uracil and cytosine
E) Xanthine and hypoxanthine - ANSWER-B.
Lesch-Nyhan syndrome presents with intellectual disability, aggressive behavior, self-
mutilation, gout, and dystonia. The disorder is due to inactivating mutations of hypoxanthine-
guanine phosphoribosyltransferase (HGPRT), a key enzyme in the purine salvage
pathway, and is inherited in an X-linked recessive fashion. HGPRT catalyzes the conversion of
guanine to guanosine monophosphate and hypoxanthine to inosine monophosphate. Patients
with deficient activity of HGPRT are unable to salvage guanine and
hypoxanthine and develop resultant increased levels of xanthine and uric acid. Hyperuricemia
in Lesch-Nyhan syndrome is treated with xanthine oxidase inhibitors, such as allopurinol or
febuxostat, in order to reduce the synthesis of uric acid.
Incorrect Answers: A, C, D and E.
Adenine and thymine (Choice A) are purine and pyrimidine bases, respectively. Purine and
pyrimidine salvage are handled through two distinct pathways that are not commonly involved
in a single disease process.
3
, Page 4 of 391
Guanine and uric acid (Choice C) accumulation may occur as part of Lesch-Nyhan syndrome,
however, the accumulation of uric acid is also secondary to accumulation of hypoxanthine.
Choice B more accurately describes defective salvage of guanine and
hypoxanthine as the fundamental effect of HGPRT dysfunction. The accumulation of uric acid is
secondary.
Uracil and cytosine (Choice D) are pyrimidine nucleotides. Pyrimidine salvage is not affected by
mutations of HGPRT.
Defects of xanthine and hypoxanthine (Choice E) metabolism may result from defects in HGPRT.
However, HGPRT dysfunction results in impaired hypoxanthine salvage with resultant excessive
production of xanthine, rather than impaired xanthine salvage.
Educational Objective: Lesch-Nyhan syndrome presents with intellectual disability, aggressive
behavior, self-mutilation, gout, and dyst
QUESTION: 2
----------
Exam Section 1: Item 3 of 50
National Board of Medical Examiners
Comprehensive Basic Science Self-Assessment
3. A 42-year-old man is struck by a motor vehicle. His only injury is a closed fracture of the
proximal tibia. Initial neurovascular examination shows no deficits. Twenty-four hours later, he
has increased leg pain and paresthesias in the dorsal space between his
4
