Parathyroid hormone lithium treatment

Many of the adverse effects of lithium can be ascribed to the action of lithium on adenylate cyclase, the key enz)nne that links many hormones and neurotransmitters with their intracellular actions. Thus antidiuretic hormone and thyroid-stimulating-hormone-sensitive adenylate cyclases are inhibited by therapeutic concentrations of the drug, which frequently leads to enhanced diuresis, h)rpoth)n oidism and even goitre. Aldosterone synthesis is increased following chronic lithium treatment and is probably a secondary consequence of the enhanced diuresis caused by the inhibition of antidiuretic-hormone-sensitive adenylate cyclase in the kidney. There is also evidence that chronic lithium treatment causes an increase in serum parathyroid hormone levels and, with this, a rise in calcium and magnesium concentrations. A decrease in plasma phosphate and in bone mineralization can also be attributed to the effects of the drug on parathyroid activity. Whether these changes are of any clinical consequence is unclear. 

Figure 9. Inverse correlation between serum calcium concentration and serum immunoreactive parathyroid hormone (iPTH) level when patient was on lithium (Li) treatment (solid line). The square denotes the normal range for serum calcium and iPTH. Solid circles denote when patient was taking lithium and open circles when lithium had been withdrawn. HCTZ = hydrochlorothiazide.

Malini S. Lithium treatment increases intact and midregion parathyroid hormone and parathyroid volume. J Clin Endocrinol Metab 1989 68 654-60. 

A number of drugs inhibit the antidiuretic actions of vasopressin. Lithium is of particular importance because of its use in the treatment of manic-depressive disorders. Lithium-induced polyuria is usually reversible. Acutely, lithium appears to reduce V -receptor-mediated stimulation of adeny-lyl cyclase. Also, hthium increases plasma levels of parathyroid hormone, a partial antagonist to vasopressin. In most patients, the antibiotic demeclocycline attenuates the antidiuretic effects of vasopressin, probably owing to decreased accumulation and action of cyclic AMP. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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