Defect seen in Bartter syndrome is

(D) Thick ascending limb of loop of Henle[?]Bartter Syndrome:-An inborn autosomal recessive defect, in the Na+-K+-2C- cotransporter in the thick ascending limb of the loop of Henle, leading to NaCl and water wasting.-Symptoms are polyuria, polydipsia, episodes of dehydration, faltering growth and constipation.-There may be maternal polyhydramnios with an affected fetus.-The resultant ECF volume contraction causes secondary renin secretion and raised aldosterone levels, with avid Na+ and water reabsorption in the distal tubule and reciprocal K+ and H+ secretion into the urine.-The blood pressure is normal; the hyperreninaemia is a compensatory response to maintain normal blood pressure in the presence of chronic ECF volume depletion.-There is also increased renal prostaglandin E2 production.[?]Fanconi Syndrome:oDiffuse proximal tubular dysfunction, leading to excess urinary loss of:-Glucose - glycosuria with normal blood glucose-Phosphate - hypophos- phataemia, rickets-Amino acids - no obvious clinical consequence-HCO3- - leading to proximal RTA-K+ - causing hypokalae- mia-Na+Cl- & water - leading to polyuria & polydipsia, chronic ECF volume depletion, faltering growth.-Tubular proteinuria - loss of low molecular weight proteins including retinol binding protein.