Ans: C (Increases...) HYDROCHLOROTHIAZIDE It inhibits Na*- Cl- symport predominantly in the DCT. In contrast to loop diuretics, which inhibit Ca2* reabsorption, thiazides actually enhance Ca2* reabsorption & decrease urine calcium excretion (causes hypercalcemia).Thiazides are useful in the treatment of kidney stones caused by hypercalciuria.' The major indications for thiazide diuretics are (1) hypertension, (2) heart failure, (3) nephrolithiasis due to idiopathic hypercalciuria, and (4) nephrogenic diabetes insipidus. "Thiazide cause carbohydrate intolerance & cause precipitation of diabetes"- KDT 7^/560 Toxicity HYPOKALEMIC METABOLIC ALKALOSIS AND HYPERURICEMIA IMPAIRED CARBOHYDRATE TOLERANCE Hyperglycemia may occur in patients who are overtly diabetic or who have even mildly abnormal glucose tolerance tests. HYPERLIPIDEMIA Thiazides cause a 5-15% increase in total serum cholesterol and low-density lipoproteins (LDL). # HYPONATREMIA Hyponatremia is an important adverse effect of thiazide diuretics. It is due to a combination of hypovolemia-induced elevation of ADH, reduction in the diluting capacity-' of the kidney, and increased thirst. It can be prevented by reducing the dose of the drug or limiting water intake. # OTHER TOXICITIES Weakness, fatigability, and paresthesias similar to those of carbonic anhydrase inhibitors may occur. Impotence has been reported but is probably related to volume depletion. # Contraindications: Excessive use of any diuretic is dangerous in hepatic cirrhosis, borderline renal failure, or heart failure