PREGUNTAS 6/03/11

1.    Un hombre de 40 años, consumidor de alcohol durante muchos año, manifiesta distensión abdominal de forma progresiva a lo largo de varios meses. Al examen físico, se encuentra arañas vasculares y eritema palmar, además de circulación colateral periumbilical y matidez desplazable. ¿Cuál de los siguientes es el paso inicial más importante en la evaluación del paciente?

a.     Paracentesis diagnóstica

b.     Radiografía de tracto GI baritada seriada

c.     Dosaje de etanol

d.     TAC abdominal

e.     Frotis de sangre periférica

2.    Un hombre de 55 años está siendo evaluado por constipación. No hay historia previa de gastrectomía o problemas de tracto GI alto. Hemoglobina 10 g/dL, Volumen Corpuscular Medio (VCM) 72 fL, Hierro sérico 4 μg/dL (normal 50-150 μg/dL), Capacidad de unión al hierro 450 μg/dL (normal 250-370 μg/dL), Saturación 1% (normal 20%-45%) y ferritina 10 μg/L (normal 15-400 μg/L). ¿Cuál de los siguientes es la mejor opción como siguiente paso en la evaluación de la anemia de este paciente?

a.    Dosaje de ácido fólico

b.    Dosaje de plomo sérico

c.    Colonoscopía

d.    Examen de médula ósea

e.    Electroforesis para hemoglobina A2 y F

3.    Una mujer de 35 años, previamente sana, manifiesta cefalea muy severa seguida de pérdida de conciencia transitoria.  No se encuentra déficit neurológico focal.  ¿Cuál de los siguientes es la mejor opción como siguiente paso en la evaluación de la paciente?

a.    TAC cerebral sin contraste

b.    TAC cerebral con contraste

c.    Angiografía cerebral

d.    Monitoreo Holter

e.    Prueba terapéutica con nortriptilina

4.    Un paciente con fiebre de bajo grado y pérdida de peso, presenta amplexación disminuida en hemitórax derecho, vibraciones vocales disminuidas, matidez a la percusión y disminución del murmullo vesicular en el lado derecho. La tráquea se encuentra desviada a la izquierda. ¿Cuál de los siguientes es el diagnóstico más probable?

a.    Neumotórax

b.    Efusión pleural

c.    Neumonía consolidada

d.    Atelectasia

e.    EPOC

5.    En un examen físico de rutina a una paciente de 28 años, se encuentra un nódulo tiroideo. No refiere dolor, cambios en el tono de voz, hemoptisis o síntomas locales; el TSH sérico es normal. ¿Cuál de los siguientes es la mejor opción como siguiente paso en la evaluación de la paciente?

a.    Ecografía de tiroides

b.    Gammagrafía de tiroides

c.    Resección quirúrgica

d.    Aspiración con aguja fina de tiroides

e.    No evaluación ulterior

1. The answer is a. (Fauci, pp 267-268, 1978-1979.) Paracentesis is

required to evaluate new-onset ascites. While cirrhosis and portal hypertension

are most likely in this patient, complicating diseases such as tuberculous

peritonitis and hepatoma are ruled out by analysis of ascitic fluid.

An ultrasound or CT scan can be used to demonstrate ascitic fluid in equivocal

cases. A serum albumin minus ascitic fluid albumin greater than 1.1

suggests portal hypertension alone as a cause for ascites. Tuberculosis, pancreatitis,

and malignancy would cause inflammation and increased capillary

permeability, causing protein to leak into the ascitic fluid. This would

result in a gradient between the serum and ascitic fluid of less than 1.1.

Upper GI radiographs are less useful than endoscopy in demonstrating the

esophageal varices that may be associated with cirrhosis. Neither serum

ethanol level nor an evaluation of the peripheral blood smear for evidence

of folate deficiency would specifically address the ascites.

2. The answer is c. (Fauci, pp 628-651.) The patient has a microcytic

anemia. A low serum iron, low ferritin, and high iron-binding capacity all

suggest iron-deficiency anemia. Most iron-deficiency anemia is explained

by blood loss. The patient’s symptoms of constipation point to blood loss

from the lower GI tract. Colonoscopy would be the highest-yield procedure.

Barium enema misses 50% of polyps and a significant minority of colon

cancers. Even patients without GI symptoms who have no obvious explanation

(such as menstrual blood loss or multiple prior pregnancies in women) for

their iron deficiency should be worked up for GI blood loss. Folate deficiency

presents as a megaloblastic anemia with macrocytosis (large, oval-shaped

red cells) and hypersegmentation of the polymorphonuclear leukocytes.

Lead poisoning can cause a microcytic hypochromic anemia, but this would

not be associated with the abnormal iron studies and low ferritin seen in

this patient. Basophilic stippling or target cells seen on the peripheral blood

smear would be important clues to the presence of lead poisoning. Although

a bone marrow examination will prove the diagnosis by the absence of stainable

iron in the marrow, the diagnosis of iron deficiency is clear from the serum

studies. Thalassemia (diagnosed by hemoglobin electrophoresis) is not associated

with abnormal iron studies. The most important issue is now to find

the source of the iron loss.

3. The answer is a. (Fauci, pp 1726-1729.) An excruciating headache with

syncope requires evaluation for subarachnoid hemorrhage. The headache that

precedes or accompanies SAH is often described as a “thunderclap” headache,

meaning that it reaches its maximum intensity in seconds. This description is

unusual in migraine (where the headache usually reaches maximum intensity

in 5-30 minutes) and mandates CT scanning or lumbar puncture. In

about 90% of patients, there will be enough blood to be visualized on a noncontrast

CT scan. If the scan is normal, a lumbar puncture is the next step to

establish the presence of subarachnoid blood. A contrast CT scan sometimes

obscures the diagnosis because, in an enhanced scan, normal arteries may be

mistaken for subarachnoid blood. Cerebral angiogram will be necessary if

SAH is present to assess for a berry aneurysm but would not be the best initial

test. Holter monitor might be helpful in unexplained syncope but would not address the severe headache. Nortriptyline can be used to prevent migraine

recurrence, but this patient’s headache does not suggest migraine; overlooking

the possibility of SAH would be a serious mistake.

4. The answer is b. (Fauci, pp 1584-1585.) The diagnosis in this patient is

suggested by the physical examination findings. The findings of poor excursion,

flatness of percussion, and decreased fremitus on the right side are all

consistent with a right-sided pleural effusion. A large right-sided effusion

may shift the trachea to the left. A pneumothorax should result in hyperresonance

of the affected side. Atelectasis on the right side would shift the trachea

to the right. A consolidated pneumonia would characteristically result in

increased fremitus, flatness to percussion, and bronchial breath sounds, and

would not cause tracheal deviation. COPD would not cause flatness to percussion

or tracheal deviation. The distant breath sounds and hyper-resonance

of COPD would be bilateral and symmetric.

5. The answer is d. (Fauci, p 2247.) Palpable thyroid nodules are common,

occurring in about 5% of all adults. Thyroid fine needle biopsy now

plays a central role in the differential diagnosis of thyroid nodules. If the TSH

is normal, as it is in this patient, then fine needle aspirate biopsy is indicated

and will distinguish cysts from benign lesions or neoplasms. In about 14% of

such cases, biopsy will be suspicious or diagnostic for malignancy and surgery

will be necessary. Thyroid scan can show a “hot” nodule, which is almost

always benign, but the TSH is suppressed in most autonomously overactive

nodules. Thyroid sonography by itself cannot rule out malignancy in palpable

nodules. Thyroid cancer can present even in a young, asymptomatic patient

like this; so option e would not be appropriate.