In Hypertrophic pyloric stenosis, which of the following is seen?

Ans. (b) Metabolic alkalosis* In HPS, hypertrophy of the circular muscle of the pylorus results in constriction and obstruction of the gastric outlet.* Most commonly clinical presentation is seen between 3-6 weeks of life* Clinical features:* Projectile nonbilious vomiting* Visible gastric peristalsis may be seen as a wave of contraction from the left upper quadrant to the epigastrium* The infants usually feed vigorously between episodes of vomiting* Typical electrolyte abnormality: Hypochloremic, hypokalemic, metabolic alkalosis with paradoxical aciduria.* Remember: Hypokalemic metabolic acidosis is seen with diarrhea.Why metabolic alkalosis and paradoxical aciduria?* Loss of stomach contents will lead to dehydration. This will trigger the R.A.A.S system into an overdrive and lead to release of aldosterone. Since aldosterone leads to potassium and hydrogen loss in the DCT of the kidney, patient will develop hypokalemic metabolic alkalosis and aciduria (paradoxically)