Anti-diuretic hormone

Urine osmolality <100 mOsm/kg (anti-diuretic hormone [ADH] suppressed)... 

The answer is c. (Katzung, p 493.) Lithium treatment frequently causes polyuria and polydipsia. The collecting tubule of the kidney loses the capacity to conserve water via anti diuretic hormone. This results in significant free-water clearance, which is referred to as nephrogenic diabetes insipidus. 

Anti-diuretic hormone is a small peptide shown as Figure 8.9, which is secreted by the pituitary gland located at the base of the brain. The cellular actions of ADH are mediated by activation of a G-protein linked receptor generating cAMP as second messenger. Absence of ADH or a functional defect in the action of ADH-stimulated water reabsorption in the collecting duct results in the condition diabetes insipidus, characterized by the passing of large volumes (= diabetes) of dilute (= insipidus) urine. 

VLc. Diabetes Insipidus and Vasopressin (Anti-diuretic Hormone)... 

Deficiency of pituitary vasopressin (arginine vasopressin or AVP, also termed anti-diuretic hormone, ADH) causes the syndrome of polyuria, thirst and polydipsia termed cranial diabetes insipidus. It is... 

Norgaard, J.P., Pedersen, E.B., and Djurhuus, J.C. (1985) Diurnal anti-diuretic-hormone levels in enuretics./ Urol 134 1029-1031. 

Delisle F. Hyponatremia and syndrome of inappropriate anti-diuretic hormone reported with the use of vincristine an over-representation of Asians ... 

Also known as water diabetes, diabetes insipidus (DI) is a rare chronic disease that causes excessive urination. If not properly treated, it can result in electrolyte imbalance and dehydration. It may be caused by a number of factors, including lithium use (a psychiatric drug used for bipolar disorder), neurological disease, or an inadequate amount of ADH (anti-diuretic hormone, or vasopressin, which is produced by the pituitary gland). DI caused by insufficient ADH is called central diabetes insipidus. 

Vasopressin (anti diuretic hormone, ADH) plays an important role in the long-term control of blood pressure through its action on the kidney to increase water reabsorption. This and other aspects of the physiology of vasopressin are discussed in Chapter 15 Diuretic Agents and Chapter 37 Hypothalamic Pituitary Hormones and will not be reviewed here. 

Xanthines, including caffeine and theophylline, are diuretics they inhibit re-absorption of Na+, increasing the GFR. Alcohol is a diuretic it reduces production of anti-diuretic hormone. 

Anti-diuretic hormone (arginine vasopressin) is a nine-amino-acid peptide secreted from the posterior pituitary. Within hypothalamic neurons, the hormone is packaged in secretory vesicles together with a carrier protein called neurophysin both are released upon secretion. 

The single most important effect of anti-diuretic hormone is to conserve body water, by reducing the loss of water in urine. In the absence of anti-diuretic hormone, the collecting ducts of the kidney are virtually impermeable to water. Anti-diuretic hormone stimulates water re-absorbtion through the insertion of water channels , or aquaporins (see Section 10.5), into the membranes of kidney tubules. Aquaporins transport solute-free water through tubular cells and back into blood, leading to a decrease in plasma osmolarity and an increased osmolarity of urine. 

Regulation of anti-diuretic hormone secretion is primarily through the plasma osmolarity. Osmolarity is sensed in the hypothalamus by neurons known as osmoreceptors, which in turn stimulate secretion from those neurons that produce anti-diuretic hormone. Secretion of antidiuretic hormone is also simulated by decreases in blood pressure and volume, conditions sensed by stretch receptors in the heart and large arteries. Changes in blood pressure and volume are not nearly as sensitive a stimulator as increased osmolarity, but are nonetheless potent in severe conditions. For example, loss of 15-20% of blood volume by haemorrhage results in a massive secretion of anti-diuretic hormone. Another potent stimulus of anti-diuretic hormone is nausea and vomiting, both of which are controlled by regions in the brain with links to the hypothalamus. 

The most common disease state related to anti-diuretic hormone is diabetes insipidus. This condition can arise from either of two simations ... 

The major indication of either type of diabetes insipidus is excessive urine production as much as 161 of urine per day. If adequate water is available for consumption, the disease is rarely fife-threatening. Hypothalamic diabetes insipidus can be treated with exogenous anti-diuretic hormone. 

Aquaporin 2 Kidney (apically) Water re-absorption in response to anti-diuretic hormone... 

Another important urinary regulatory mechanism involves the effects of vasopressin (AVP) also known as anti diuretic hormone (ADH). A decrease in blood pressure or an elevation in plasma osmolality will result in the release of ADH from the posterior... 

Syndrome of inappropriate anti-diuretic hormone (SIADH), which causes water retention and sodium loss... 

Pellicone JT, Goldstein HB. Pulmonary malignant angioendotheliomatosis Presentation with fever and syndrome of inappropriate anti-diuretic hormone. Chest. 1990 98 1292-1294. 

S43, Vasopressin, Anti diuretic hormone beta-hypo-phamine /3-hypophamine Leiomnone Pitressin Tonephm Vasophysin. The water-soluble pressor principle prepd by synthesis or obtained from the posterior lobe of the pituitary of healthy domestic animals used for food by man V.S.P. XVIII, 770. Separation from oxytocin Kamm el at., J. Am. 

Syndrome of Inappropriate Anti-Diuretic Hormone (SIADH), which causes abnormal water retention (sodium loss) or Addison s Disease,... 

A case of hyponatraemia resembling anti-diuretic hormone excess induced by phen-formin has been reported (44 ). 

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