USMLE Step 1 Practice Test 10
10 free USMLE Step 1 practice questions in the real exam format, covering the official content areas, with an explanation for every answer.
Question 1 of 10
Respiratory & Renal/Urinary SystemsQuestion: Which of the following is the most likely mechanism of this patient's kidney injury?
Patient Information Age: 8 years Gender: F, self-identified (by parent) Race/Ethnicity: Hispanic, self-identified (by parent) Site of Care: emergency department
History Reason for Visit/Chief Concern: "My pee looks like cola." History of Present Illness: • 2 days of dark urine and decreased urine output • puffy eyelids each morning for 2 days • sore throat with fever 2 weeks ago that resolved without treatment Past Medical History: no serious illness Medications: none Allergies: no known drug allergies Family History: no kidney disease Psychosocial History: lives with her parents and younger brother; attends third grade
Physical Examination
| Temp | Pulse | Resp | BP | O2 Sat | Ht | Wt | BMI |
|---|---|---|---|---|---|---|---|
| 37.0°C (98.6°F) | 92/min | 20/min | 138/90 mm Hg | 98% on room air | 128 cm (4 ft 2 in) | 28 kg (62 lb) | 17 kg/m² |
• Periorbital edema and mild pretibial edema • Pharynx: no erythema or exudate • Skin: no rash • Joints: no swelling or tenderness
Diagnostic Studies
| Test | Result |
|---|---|
| Blood | |
| Hemoglobin | 12.2 g/dL |
| Platelet count | 290,000/mm³ |
| Serum | |
| Urea nitrogen | 28 mg/dL |
| Creatinine | 1.0 mg/dL |
| Complement C3 | decreased |
| Complement C4 | normal |
| Anti-DNase B antibody | increased |
| Urine | |
| Blood | 3+ |
| Protein | 1+ |
| RBCs | 40–50/hpf, dysmorphic |
| Casts | RBC casts |