Anesthesia Pharmacology: Renal Pharmacology
Mechanisms whereby furosemide and thiazides are useful in calcium metabolism disorders management
Loop Diuretics and Calcium Metabolism
Inhibition of NaCl reabsorption in the thick ascending limb of the loop of Henle
Inhibit the Na+/K+/2Cl- transport system in the luminal membrane
Reduction in sodium chloride reabsorption
decreases normal lumen-positive potential (secondary to potassium recycling)
Positive lumen potential: drives divalent cationic reabsorption (calcium magnesium)
Therefore, loop diuretics increase magnesium and calcium excretion.
Hypomagnesemia may occur in some patients.
Hypocalcemia does not usually develop because calcium is reabsorbed in the distal convoluted tubule.
In circumstances that result in hypercalcemia, calcium excretion can be enhanced by administration of loop diuretics with saline infusion.
Thiazides and Calcium Metabolism
Mechanism of action:
Diuretic action:Inhibition of NaCl reabsorption from the distal convoluted tubule (luminal side)
Enhanced calcium reabsorption in the distal convoluted tubule (unknown mechanism)
Thiazides infrequently cause hypercalcemia but can unmask hypercalcemia due to other causes such as carcinoma, sarcoidosis, or hyperparathyroidism.
Jackson, E.K. Vasopressin and Other Agents Affecting the Renal Conservation of Water In, Goodman and Gillman's The Pharmacological Basis of Therapeutics,(Hardman, J.G, Limbird, L.E, Molinoff, P.B., Ruddon, R.W, and Gilman, A.G.,eds) The McGraw-Hill Companies, Inc.,1996, pp.715-732
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