All of the following are seen in chronic pyloric obstruction except: March 2010

Ans. A: Alkaline urine Paradoxical aciduria occurs when a metabolic alkalosis caused by severe vomiting as seen in pyloric obstruction. Blood tests initially will reveal hypochloremic metabolic alkalosis due to loss of hydrochloric acid vomiting, but sodium and potassium levels are normal. However as dehydration progresses, more profound metabolic abnormalities arise, paly due to renal dysfunction. Initially the urine has low chloride and high bicarbonate content, reflecting primary metabolic abnormality. This bicarbonate is excreted along with sodium and so, with time patient becomes progressively hyponatremic and more profoundly dehydrated. Because of dehydration, a phase of sodium retention follows and potassium and hydrogen are excreted in preference. This results in urine becoming paradoxically acidic and hypokalemia ensues.