USMLE Exam 1

Question 1

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Accepted Answer

Brachial artery

Answer

The brachial artery is the main artery of the upper arm, a continuation of the axillary artery. It is a crucial anatomical landmark for various medical procedures, including blood pressure measurement and arterial access. Its significant role in supplying blood to the forearm and hand makes it a frequently tested structure in anatomy and clinical contexts.

Question 2

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Accepted Answer

5α-reductase deficiency

Answer

5α-reductase deficiency is a disorder of sex development where testosterone cannot be converted to dihydrotestosterone (DHT). DHT is essential for the development of external male genitalia in utero. Individuals with this XY genetic makeup may present with ambiguous genitalia at birth, often virilizing at puberty due to increased testosterone.

Question 3

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Accepted Answer

Isospora belli

Answer

Isospora belli (now Cystoisospora belli) is an intestinal parasite known to cause isosporiasis, a diarrheal illness. It is particularly associated with chronic, watery diarrhea in immunocompromised individuals, such as those with HIV/AIDS. Diagnosis involves identifying oocysts in stool, and treatment typically uses trimethoprim-sulfamethoxazole.

Question 4

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Accepted Answer

Creatinine clearance

Answer

Creatinine clearance is the most commonly used clinical measure to estimate the glomerular filtration rate (GFR), which reflects overall kidney function. It quantifies the volume of blood plasma cleared of creatinine per unit time. This provides a practical and relatively accurate assessment of how well the kidneys are filtering waste products from the blood.

Question 5

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Accepted Answer

CA-125

Answer

CA-125 (Cancer Antigen 125) is a tumor marker primarily used in the management of ovarian cancer. Elevated levels are often found in women with epithelial ovarian cancer, and it is utilized for monitoring treatment response and detecting recurrence. While not specific enough for definitive diagnosis alone, it is a valuable tool in conjunction with imaging and clinical evaluation.

USMLE Practice Test

USMLE Practice Test

USMLE Exam 1