SIADH syndrome of inappropriate antidiuretic hormone

Causes of nonosmotic release of arginine vasopressin, commonly known as antidiuretic hormone, include hypovolemia decreased effective circulating volume as seen in patients with congestive heart failure nephrosis cirrhosis and syndrome of inappropriate antidiuretic hormone (SIADH) release. 

Nephrogenic diabetes insipidus is due to resistance to action of vasopressin, and therefore DDAVP is not indicated, but some benefit may be gained by using thiazide diuretics or chlorpropamide. The syndrome of inappropriate antidiuretic hormone (SIADH) can be treated by using the antibiotic derivative demeclocycline to induce a state of vasopressin resistance and partial nephrogenic diabetes insipidus. 

Bouman WP Pinner G, lohnson H. Incidence of selective serotonin reuptake inhibitor (SSRI) induced hyponatraemia due to the syndrome of inappropriate antidiuretic hormone (SIADH) secretion in the elderly. Int 1 Geriatr Psychiatry 1998,13 12-15. 

The syndrome of inappropriate antidiuretic hormone (SIADH) secretion is a condition in which secretion of ADH continues despite serum hypo-osmolarity. This results in fluid retention and hyponatremia that can lead to brain oedema, mental confusion and coma. The causes are hypothalamic-pituitary tumours or an ectopic vasopressin-secreting tumour. 

The mechanism of hyponatremia is unclear. Where documented, 4 out of the 6 cases describe a scenario consistent with syndrome of inappropriate antidiuretic hormone (SIADH). In one case, a 66 year old woman... 

Tetracyclines are the first broad-spectrum antibiotic used to impede the growth of gram-positive and -negative bacteria. Tetracyclines are prescribed for acne vulgaris, actinomycosis, anthrax, bronchitis, and urinary tract infections. Demeclocycline, a member of the tetracycline family, is also prescribed for syndrome of inappropriate antidiuretic hormone (SIADH). Demeclocycline inhibits water-induced reabsorption in the kidneys. 

Determination of plasma and urine osmolality can be useful in the assessment of electrolyte and acid-base disorders. Comparison of plasma and urine osmolalities can determine the appropriateness and status of water regulation by the kidneys in settings of severe electrolyte disturbances, as might occur in diabetes insipidus or the syndrome of inappropriate antidiuretic hormone (SIADH) (see Chapters 45 and 50). The major osmotic substances in normal plasma are Ha, Cr, glucose, and urea thus expected plasma osmolality can be calculated from the following empirical equation ... 

BOX 50-M Diagnosis of Syndrome of Inappropriate Antidiuretic Hormone (SIADH)... 

The HCP ordered furosemide (Lasix) for a client diagnosed with syndrome of inappropriate antidiuretic hormone (SIADH). Which laboratory test would be monitored to determine the effectiveness of the medication ... 

Endocrine The syndrome of inappropriate antidiuretic hormone (SIADH) has been associated with lopinavir in an HIV-infected 13-year-old boy [122 ]. 

Relatedly, malfunction of one of the sodium-water control mechanisms, such as a kidney that normally excretes excess water, can result in fluid retention and dilutional hyponatremia. The pituitary gland and hypothalamus function to release ADH (which controls water reabsorption), and the cortex of the adrenal gland seaetes aldosterone (which controls sodium reabsorption). An alteration in the function of either of these hormone systems will alter the body s regulation of sodium or water and can result in hyponatremia. 2 For example, in the syndrome of inappropriate antidiuretic hormone (SIADH), excessive ADH is produced (usually by a tumor or some pulmonary diseases such as tuberculosis or bacterial pneumonia), and the kidneys reabsorb excessive fluids, resulting in dilutional hyponatremia. Conditions causing decreased aldosterone secretion include... 

Syndrome of inappropriate antidiuretic hormone is defined by water retention, dilutional hyponatraemia and decreased volume of highly concentrated urine. There are several causes which can result in SIADH, neoplasms ectopic secreting AVP, ectopic release of AVP by various diseases or drugs, exogenous administration of AVP, desmopressin, lysipressin or large doses of OT (iatrogenic SLADH). 

SIADH Syndrome of inappropriate antidiuretic hormone TID Three times daily (ter in die)... 

FIGURE 78-1. Diagnostic algorithm for the evaluation of hyponatremia. (CHF, congestive heart failure EABV, effective arterial blood volume SIADH, syndrome of inappropriate antidiuretic hormone UNa, urine sodium concentration Uosm, urine osmolality.)... 

Hyponatremia Hyponatremia and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) may occur with venlafaxine. 

Abbreviations CNS, central nervous system COX, cyclooxygenase Gl, gastrointestinal NSAlDs, nonsteroidal anti-inflammatory drugs SIADH, syndrome of inappropriate antidiuretic hormone secretion. From Pick DM, Cooper IW, Wade WE, et al Updating the Beers criteria for potentially inappropriate medication use in older adults Results of a U.S. consensus panel of experts. Arch Intern Med 2003 163 2716. 

In an unusual case reported in detail from Saudi Arabia, a 28-year-old woman receiving gonadotropins developed acute respiratory distress, abdominal pain, and severe hyponatremia associated with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) (19). A multiple pregnancy nevertheless resulted and three fetuses went to term successfully. 

Furosemide rarely causes the syndrome of inappropriate antidiuretic hormone secretion (SIADH) (although it has been found useful in treating some patients with SIADH who cannot tolerate water restriction (428)). In furosemide-induced cases (SEDA-7, 246), serum ADH concentrations were raised, total body sodium was normal, total body potassium greatly reduced, and intracellular water raised at the expense of extracellular fluid volume. However, such cases are rare, and no new cases have been published since this complication was reported in SEDA-7. 

Ikegami H, Shiga T, Tsushima T, Nirei T, Kasanuki H. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) induced by amiodarone a report on two cases. J Cardiovasc Pharmacol Ther 2002 7(l) 25-8. 

Castrillon JL, Mediavilla A, Mendez MA, Cavada E, Carrascosa M, Valle R. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) and enalapril. J Intern Med 1993 233(1) 89-91. 

Hyponatremia is caused by an excess of total body water relative to total body sodium and can result from a number of underlying conditions, including the syndrome of inappropriate antidiuretic hormone secretion (SIADH), cirrhosis, and congestive heart failure (CHF). In each of these conditions, inappropriate production of arginine vasopressin (AVP) [also known as vasopressin or antidiuretic hormone (ADH)], a neurohormone that regulates renal electrolyte-free water reabsorption, contributes to enhanced renal water retention, leading to decreased serum sodium concentrations.7 Hyponatremia can be characterized as hypervolemic, euvolemic, or hypovolemic... 

Since SSRIs can sometimes also reduce sodium due to SIADH (syndrome of inappropriate antidiuretic hormone production), patients treated with combinations of oxcarbazepine and SSRIs should be carefully monitored, especially in the early stages of treatment... 

---