Lithium

How can lithium affect your kidneys?

[Dr_Aparna]

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-  Lithium is a univalent cation of the white metal series, closely related to both sodium and potassium, but having no known role in human physiology. Lithium is completely absorbed by the GI tract. The drug is not \protein bound and is completely filtered at the glomerulus. The majority of the filtered load is reabsorbed by the proximal tubule, but significant amounts are also absorbed in the loop of Henle and the early distal nephron. Up to 90% of the filtered load is reabsorbed by the nephron.Lithium can substitute for sodium in several sodium channels, particularly the sodium-hydrogen exchanger in different parts of the nephron.The nephron is the functional unit of the kidney.Acutely and chronically, lithium salts produce a natriuresis resulting in inappropriate sodium losses .The most common complication of chronic lithium therapy is nephrogenic diabetes insipidus.this results in the symptoms of polyuria-increased urination and polydipsia-increased thirst.
ref:eMedicine  Lithium Nephropathy : Articleby Eleanor Lederer
www.emedicine.com/med/topic1313.htm