Physician Assistant Formulating a Diagnosis 3 — Questions and Answers
Question 1: A PA is evaluating a 40-year-old with fatigue, weight gain, cold intolerance, and constipation. Which diagnosis fits this illness script best?
- Hypothyroidism (Correct answer)
- Addison's disease
- Type 2 diabetes mellitus
- Depression
Correct answer: Hypothyroidism
Fatigue, weight gain, cold intolerance, and constipation together form the classic illness script for hypothyroidism, driven by reduced metabolic activity.
Question 2: Which diagnostic approach is most appropriate when two diagnoses on a differential have similar presentations but very different treatments?
- Order the test with the highest likelihood ratio for the most dangerous diagnosis (Correct answer)
- Treat empirically for the more common diagnosis
- Wait for all symptoms to resolve spontaneously
- Consult subspecialty immediately without further workup
Correct answer: Order the test with the highest likelihood ratio for the most dangerous diagnosis
When dangerous diagnoses must be ruled out, prioritizing tests with the highest likelihood ratios for the most life-threatening condition ensures patient safety.
Question 3: A 35-year-old man presents with sudden severe headache described as 'the worst of my life.' Which diagnosis is the priority to exclude?
- Subarachnoid hemorrhage (Correct answer)
- Migraine with aura
- Tension headache
- Cluster headache
Correct answer: Subarachnoid hemorrhage
A thunderclap headache—sudden and maximal at onset—mandates urgent evaluation to exclude subarachnoid hemorrhage, a neurological emergency.
Question 4: Which finding most strongly supports a diagnosis of heart failure with preserved ejection fraction (HFpEF) over chronic obstructive pulmonary disease (COPD) in a dyspneic patient?
- Elevated BNP with bilateral crackles and orthopnea (Correct answer)
- Barrel chest with prolonged expiratory phase
- Increased resonance on percussion
- Pursed-lip breathing
Correct answer: Elevated BNP with bilateral crackles and orthopnea
Elevated BNP, bilateral crackles, and orthopnea are cardinal features of heart failure that help distinguish HFpEF from obstructive lung disease.
Question 5: A PA considers the sensitivity of a test when ruling out a disease. Which mnemonic aids this reasoning?
- SnNout — a highly Sensitive test, when Negative, rules OUT disease (Correct answer)
- SpPin — a highly Specific test, when Negative, rules IN disease
- SnPin — a highly Sensitive test, when Positive, rules IN disease
- SpNout — a highly Specific test, when Negative, rules OUT disease
Correct answer: SnNout — a highly Sensitive test, when Negative, rules OUT disease
SnNout indicates that a highly sensitive test with a negative result effectively rules out the disease due to its low false-negative rate.
Question 6: A 50-year-old presents with polyuria, polydipsia, and a fasting glucose of 136 mg/dL on two separate occasions. Which diagnosis is confirmed?
- Type 2 diabetes mellitus (Correct answer)
- Diabetes insipidus
- Prediabetes
- Gestational diabetes
Correct answer: Type 2 diabetes mellitus
Fasting plasma glucose ≥126 mg/dL on two separate occasions meets the ADA diagnostic criteria for type 2 diabetes mellitus.
Question 7: When using a clinical decision rule such as the Wells Score for DVT, what is its primary purpose in diagnostic reasoning?
- To stratify pre-test probability and guide selection of subsequent diagnostic testing (Correct answer)
- To replace the need for imaging in all patients
- To confirm the diagnosis without laboratory testing
- To determine the appropriate anticoagulation dose
Correct answer: To stratify pre-test probability and guide selection of subsequent diagnostic testing
Clinical decision rules like the Wells Score quantify pre-test probability to guide whether imaging is warranted, reducing unnecessary testing in low-risk patients.
Physician Assistant Formulating a Diagnosis 3
A PA is evaluating a 40-year-old with fatigue, weight gain, cold intolerance, and constipation.
Which diagnosis fits this illness script best?