Antidiuretic hormone measurement is used in the diagnosis of diabetes insipidus, psychogenic water poisoning, inappropriate antidiuretic hormone secretion syndrome, and in ectopic production of antidiuretic hormone.
Antidiuretic hormone (ADH), originally known as vasopressin, is a hormone produced by the hypothalamus. It is stored in the posterior pituitary lobe and released when required, depending on serum osmolarity. A high serum osmolarity value indicates that the serum concentration is increased and that the amount of water is limited, thereby releasing the antidiuretic hormone. The antidiuretic hormone increases the permeability of the distal renal tubules and the collecting ducts, in order to reabsorb water. On the contrary, a low serum osmolarity indicates that there is excess water and the serum density is low. In this condition, the secretion of antidiuretic hormone is reduced, leading to increased secretion of water (diuresis).
Some conditions may lead to abnormal secretion or lack of secretion of antidiuretic hormone or lack of renal response to secretion of antidiuretic hormone. In diabetes insipidus, either inadequate secretion of antidiuretic hormone occurs or the kidneys do not respond appropriately to antidiuretic hormone. Causes of diabetes insipidus include head trauma, brain tumor or inflammation, neurosurgery, or primary kidney disease. In the syndrome of inappropriate antidiuretic hormone secretion (SIADH), there is a continuous release of the hormone in the presence of low plasma osmolality. This syndrome can be caused by ectopic production of anti-diuretic hormone by lung, thymic, pancreatic, intestinal, and urinary tract tumors as well as certain lung conditions or by severe stress.
What Do Pathological Rates Mean?
- Increase: Acute porphyria, Addison's disease, brain tumors, lung cancer, circulatory shock, ectopic ADH secretion, hemorrhage, hepatitis, hypothyroidism, nephrogenic diabetes insipidus, pneumonia, stress, inappropriate antidiuretic hormone secretion (SIADH) syndrome, tuberculosis.Medications: paracetamol, anesthetics, barbiturates, carbamazepine, chlorothiazide, chloropropamide, cyclophosphamide, estrogen, lithium, morphine, nicotine, oxytocin, vincristine.
- Decrease: Central (pituitary) diabetes insipidus, head trauma, hypovolemia, hypothalamic tumors, metastatic disease, neurosurgery, sarcoidosis, syphilis, viral infection. Medications: alcohol, phenytoin.
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. The correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings, and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.