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: Pediatrics
The metabolic derangement in congenital pyloric stenosis is – 
Select and explain. 
A. Hypochloremic alkalosis, B. Hyperchloremic alkalosis, C. Hyperchloremic acidosis, D. Hypochloremic acidosis
A: Hypochloremic alkalosis
Answer: A: Hypochloremic alkalosis 
Explanation: Clinical manifestations of congenital hypertrophic pyloric stenosis 

Pyloric stenosis is usually not present at birth.
Nonbullous vomiting is the initial symptoms of pyloric stenosis.
The vomiting usually starts after 3 weeks of age, but symptoms may develop as early as the 1st week of life and as late as the 5 months of life.
Emesis may follow each feeding, or it may be intermittent.
After vomiting, the infant is hungry and wants to feed again.
Due to vomiting, there is a progressive loss of→ Fluid, Hydrogen ion, Chlorides
This results in hypochloremic metabolic alkalosis.
Serum potassium levels are usually maintained, but there may be a total body potassium deficit.
Jaundice (unconjugated bilirubin) is associated with a decreased level of glucuronyl transferase in 5% of patients.