Examkin

Question

Difficulty: EasyOrdering Laboratory Tests

Match the following patient clinical presentations to the most appropriate initial laboratory evaluation to establish a diagnosis.

  • A 42-year-old woman with a BMI of 32 kg/m², acanthosis nigricans, and recent onset of increased thirst and frequent urination.Hemoglobin A1c measurement
  • A 24-year-old pregnant woman at 26 weeks gestation presenting for a routine second-trimester prenatal care visit.1-hour 50-g oral glucose challenge test
  • A 55-year-old man with acute onset of severe, excruciating pain, swelling, and erythema of the first metatarsophalangeal joint.Arthrocentesis for synovial fluid crystal analysis
  • An 18-year-old man with a 2-day history of sore throat, fever of 39.0°C (102.2°F), tonsillar exudates, and absence of cough.Rapid streptococcal antigen test

Answer

Symptoms of type 2 diabetes mellitus match with Hemoglobin A1c measurement; a routine 26-week pregnancy visit matches with the 1-hour 50-g oral glucose challenge test; an acute podagra presentation matches with arthrocentesis for crystal analysis; and pharyngitis meeting Centor criteria matches with the rapid streptococcal antigen test.
Each correct pairing matches a classic clinical vignette with its gold-standard initial laboratory or diagnostic test. The 42-year-old woman shows clear signs of insulin resistance and hyperglycemia, warranting a Hemoglobin A1c test. The 24-year-old pregnant woman is at the standard gestational age for gestational diabetes screening using the 50-g oral glucose challenge. The 55-year-old man presents with podagra, requiring joint aspiration (arthrocentesis) to confirm gout and rule out infection. The 18-year-old meets Centor criteria for suspected strep throat, requiring confirmation with a rapid strep test before empiric treatment.

Step-by-Step Solution

1
Analyze the first clinical presentation (BMI 32 kg/m², acanthosis nigricans, polyuria, polydipsia).
Identify the likely diagnosis as type 2 diabetes mellitus.
The patient presents with classic osmotic symptoms and physical exam findings indicating insulin resistance.
2
Determine the initial laboratory test for suspected diabetes.
Select Hemoglobin A1c measurement.
Hemoglobin A1c is a highly specific, standardized initial test for establishing the diagnosis of diabetes mellitus.
3
Evaluate the second presentation (26 weeks gestation routine prenatal care).
Recognize the need for universal gestational diabetes screening.
Obstetric guidelines mandate screening between 24 and 28 weeks of gestation with an oral glucose challenge test.
4
Assess the third presentation (acute painful swelling of the first metatarsophalangeal joint).
Identify podagra, highly suggestive of an acute gout flare.
The sudden onset of severe monoarticular arthritis in this specific joint is the classic presentation for crystalline arthropathy.
5
Determine the diagnostic test of choice for suspected gout.
Select arthrocentesis for synovial fluid analysis.
Joint aspiration confirms the presence of monosodium urate crystals and rules out an infectious etiology (septic arthritis).
6
Examine the fourth presentation (fever, sore throat, tonsillar exudates, no cough in a young adult).
Apply the Centor criteria, noting a score of 4.
A high Centor score suggests a high probability of Group A streptococcal pharyngitis.
7
Select the appropriate initial laboratory test for this Centor score.
Choose the rapid streptococcal antigen test.
Testing is indicated to confirm the bacterial etiology and guide appropriate antibiotic therapy to prevent complications like rheumatic fever.

Key Concept

Selecting the most appropriate initial diagnostic laboratory test based on the patient's acute clinical presentation, demographic risk factors, and established screening guidelines.
Rate this question

Topics

Ordering Laboratory Tests

More questions from this topic