A 4-year-old patient presents to the nurse practitioner for a routine exam, and the NP suspects hypertension. The test that would be the LEAST helpful in evaluating the etiology of hypertension in this age group would be:

Rationale: A. Urinalysis can detect hematuria, proteinuria, or signs of urinary tract infection, which may indicate renal causes of pediatric hypertension, making it a helpful test. B. Complete blood count (CBC) may reveal anemia or other hematologic abnormalities that could contribute indirectly to hypertension or help identify underlying systemic conditions. C. Renal ultrasound is essential for evaluating structural kidney abnormalities, which are a common cause of hypertension in young children. D. Liver enzymes (AST, ALT) are least helpful in determining the cause of hypertension in a 4-year-old, as liver disease is rarely a primary contributor to pediatric hypertension at this age.