This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Unknown
A five year old boy presents with precocious puberty and a blood pressure of 130/80 mmHg. Estimation of which of the following will help in diagnosis - 
Select and explain. 
A. | 17 hydroxy-progesterone, B. | Cortisol, C. | Aldosterone, D. Renin
A: | 17 hydroxy-progesterone
Answer: A: | 17 hydroxy-progesterone 
Explanation: Ans- A. Ref- Nelson Textbook Of Pediatrics Vol. 1 20th ed Biochemical diagnostic studies show elevated levels of serum 17-OHP, the substrate for the defective 21-hydroxylase enzyme activity.