However, prior to a water deprivation test, consideration should be given to a psychiatric consult to see whether it is possible to rule out psychogenic polydipsia or habit polydipsia. Diagnosis
Polydipsia is a symptom (evidence of a disease state), not a disease in itself. As it is often accompanied by polyuria (excessive urination) and low sodium levels. Investigations directed at diagnosing diabetes insipidus and diabetes mellitus can be useful. Blood serum tests can also provide useful information about the osmolality of the bodys extracellular fluids. A decrease in osmolality caused by excess water intake will decrease the serum concentration of red blood cells, blood urea nitrogen (BUN), and sodium. See also
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It is also a short-lived effect because the kidneys become resistant to calcitonin, as demonstrated by the kidneys unaffected excretion of calcium in patients with thyroid tumors that secrete excessive calcitonin.In its skeleton-preserving actions, calcitonin protects against calcium loss from the skeleton during periods of calcium mobilization, such as pregnancy and, especially, lactation. The protective mechanisms include the direct inhibition of bone resorption and the indirect effect through the inhibition of the release of prolactin from the pituitary gland. The reason provided is that prolactin induces the release of PTH related peptide which enhances bone resorption, but is still under investigation.Other effects are in preventing postprandial hypercalcemia resulting from absorption of Ca2+. Also, calcitonin inhibits food intake in rats and monkeys, and may have CNS action involving the regulation of feeding and appetite. Calcitonin lowers blood calcium and phosphorus mainly through its inhibition of osteoclasts. Osteoblasts do not have calcitonin receptors and are therefore not directly affected by calcitonin levels. However, since bone resorption and bone formation are coupled processes, eventually calcitonins inhibition of osteoclastic activity leads to increased osteoblastic activity (as an indirect effect). Receptor
The calcitonin receptor is a G protein-coupled receptor localized to osteoclasts as well kidney and brain cells. It is coupled to a Gsα subunit, thus stimulating cAMP production by adenylate cyclase in target cells. It may also affect the ovaries in women and the testes in men. Discovery
Calcitonin was first purified in 1962 by Douglas Harold Copp and B. Cheney at the University of British Columbia, Canada.