QUESTIONS WITH VERIFIED SOLUTIONS
NEW MODIFIED WITH RATIONALES
Question
A 24-year-old woman presents with severe diarrhea that she has been experiencing for 3
days, with no medical issues before then. She now feels dizzy upon standing, her tongue is
dry, and her eyes appear glazed. Her serum sodium concentration is 130 mEq/L. What
finding is most likely? ---Correct answer:
Increased serum ADH concentration
Explanation
The patient has obvious symptoms of dehydration. She also has a low serum sodium
concentration, which shows that the body's drive to conserve water supersedes that of
maintaining an adequate sodium concentration.
ADH makes the normally impermeable collecting tubules permeable to water. ADH promotes
water reabsorption in the collecting tubules, so urine volume is decreased and urine osmolality
is increased. The patient's condition can be readily explained in view of an increased level of
serum ADH.
Serum aldosterone will be increased, as the body will also be trying to conserve sodium.
Atrial natriuretic peptide will be decreased for the same reason.
Case Ico-delete Highlights
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,A 29-year-old man is seen in clinic for groin pain. He works as a cashier at a local
supermarket. The pain increases through the day. When asked to point out its location, he
localizes it to his left groin fold. Examination of his inguinoscrotal region reveals an ill-
defined tortuous swelling that increases with standing, with a palpable thrill on coughing.
Question
What is the best next step in diagnosis? ---Correct answer:
Ultrasound
Explanation
Ultrasonography is the correct answer. Ultrasound reliably diagnoses varicoceles. Being
quick, reliable and non-invasive, it is the diagnostic test of choice. Sensitivity increases with
the concomitant use of Doppler. Pampiniform plexus venous dilation of over 2 mm with
standing or Valsalva maneuver is considered diagnostic.
Diagnostic laparoscopy is incorrect. The pathology lies in the inguinal region extending to the
scrotum, and it does not need laparoscopy.
Venography is incorrect. While it is highly accurate, it remains an invasive technique; there is
exposure to ionizing radiation. It is rarely (if ever) necessary in the age of ultrasonography.
Computerized tomography (CT) is incorrect. If other tests indicated testicular cancer, a CT of
the chest, abdomen and pelvis may be undertaken to inspect for metastasis.
MRI is incorrect. It is unnecessary because ultrasonography is of such high sensitivity.
Case Ico-delete Highlights
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,A 28-year-old woman receives a lung transplant due to cystic fibrosis. 2 months after the
transplant day, she is readmitted with paralysis of the left body. A basal ganglia stroke is
diagnosed by computed tomography (CT). After 2 weeks of hospital stay, she shows signs of
cardiac failure and is intubated. A posterior mitral valve leaflet vegetation with severe
regurgitation is identified by transesophageal echocardiography (TEE). She is submitted to
mechanical mitral valve replacement. Colonies of Aspergillus fumigatus are detected in the
excised mitral valve leaflets. Intravenous anti-fungal therapy with amphotericin B is started. 8
days later, she presents with fever, shortness of breath, and edema. A rapid increase in
creatinine levels is observed. Fraction of excretion of sodium (FENa) is increased (> 3%), and
urine analysis reveals epithelial casts.
Question
In what example would ---Correct answer:
Acute tubular necrosis
Explanation
The clinical and laboratory findings of the vignette point to the diagnosis of acute tubular
necrosis (ATN). In cases of ATN, cells heal completely by regeneration. Epithelial cells that
line the kidney tubules are destroyed by ischemia (e.g. hypovolemic shock, sepsis, cardiac
heart failure), toxins (e.g., aminoglycosides, amphotericin B as in this case, contrast media,
lead, cisplatin), myoglobinuria in rhabdomyolysis, or hyperurecemia in acute tumor lysis. Re-
absorptive mechanisms of sodium and water are lost with the tubular cells and acute renal
failure occur. 2 features corroborate for the regeneration in ATN to be complete: 1) necrosis
occurs in a patchy pattern; 2) the collagen framework of the tubules (epithelial basal
membrane and the interstitium) remains intact. The existing epithelial cells replicate using the
basement membrane as a guide, and they bring the kidney back to normal. After regeneration
is complete, the damage is undetectable, even microscopically.
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, In contrast, healing will take place by repair when the causative process affects the kidney
collagen framework. While enzymes released by inflammatory cells in chronic pyelonephritis
damage this framework, an infarction leads to its total collapse. Because of the history of
previous cerebral infarction and fungus endocarditis, the possibility of another embolization
with kidney infarction in this case is high. However, the clinical and laboratory findings do not
support this diagnosis.
Diffuse cortical necrosis (DCN) is an acute generalized cortical infarction of both kidneys,
leading to atrophy of the cortex with preservation of the medulla. DCN is the pathological
progression of ATN: once rapidly corrected, acute renal ischemia leads to ATN. A more
prolonged ischemia may lead to DCN.
Case
A 62-year-old woman is being treated for chronic congestive heart failure. She has been put on
hydrochlorothiazide therapy. Her serum electrolyte levels are being monitored and show a
persistent hypokalemia.
Question
The addition of what to her therapeutic regimen would be most appropriate? ---Correct
answer:
Amiloride
Explanation
Amiloride is a potassium-sparing diuretic. Its diuretic effect is not very potent; therefore, it is
good to use in combination with other diuretics.
Acetazolamide is a carbonic anhydrase inhibitor. It causes a mild diuresis, a marked elevation
of urinary pH, and a significant loss of potassium.
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