Inappropriate ADH

Carbamazepine stimulates antidiuretic hormone activity and has been used for the treatment of neurohypophyseal diabetes insipidus. Carbamazepine induces microsomal enzymes and its metabolism is subject to auto-induction. Frequently occurring adverse effects are sedation, dry mouth, dizziness and gastrointestinal disturbances. Photosensitivity reactions, urticaria and Stevens-Johnson syndrome have been described. The elderly are more prone to mental confusion, cardiac abnormalities and problems due to inappropriate ADH secretion. 

Tetracyclines block ADH in the kidney and especially demeclocycline is used to treat the syndrome of inappropriate ADH secretion. 

Syndrome of inappropriate ADH secretion (SIADH) PO Initially, 900-1200 mg/day in 3-4 divided doses, then decrease dose to 600-900 mg/day in divided doses. 

Side effects are usually associated with the increasing serum concentration of theophylline and includes nausea, vomiting, headache, insomnia, tachypnea, epigastric pain, palpitation, hypotension, irritability. Higher doses can cause persistent vomiting, cardiac arrhythmias, intractable seizures, tachycardia. Other side effects include alopecia, hyperglycemia, inappropriate ADH syndrome, rash. 

Adverse effects include local reaction if extravasation occurs, constipation, paralytic ileus, jaw pain, alopecia, bone marrow depression, peripheral neuropathy, inappropriate ADH secretion, shortness of breath and bronchospasm. 

Amilohde and indomethacin are the most effective therapies for polyuria/polydipsia and syndrome of inappropriate ADH, respectively ( 77). 

Because CBZ can cause hyponatremia, it should be used cautiously in patients on a salt-restricted diet ( 373). Hyponatremia is rarely clinically significant when sodium values are above 125 mmol/L. Low sodium levels, as well as concomitant diuretic and lithium users, may predispose to the development of the syndrome of inappropriate ADH. Since CBZ enhances the effects of ADH, it can lead to impairment of free water clearance from the body. Older patients are at higher risk and should be closely monitored for this adverse effect which can be managed by dose reduction of CBZ. More severe cases, however, usually require switching to... 

The most important stimulus to the release of ANP from the heart is atrial stretch via mechanosensitive ion channels. ANP release is also increased by volume expansion, changing from the standing to the supine position, and exercise. ANP release can also be increased by sympathetic stimulation via aiA-adrenoceptors, endothelins via the -receptor subtype (see below), glucocorticoids, and vasopressin. Plasma ANP concentration increases in various pathologic states, including heart failure, primary aldosteronism, chronic renal failure, and inappropriate ADH secretion syndrome. 

Samman Y, Ghoneim H, Hashim IA. Syndrome of inappropriate ADH as a manifestation of severe ovarian hyperstimulation syndrome. J Obstet Gynaecol 2001 21 201-3. 

Neuroendocrine effects of neuroleptic drugs include a rise in growth hormone, inappropriate ADH and prolactin secretion, and disturbances of sex hormones (SEDA-7, 67). Galactorrhea (SEDA-20, 43) and gynecomastia can follow the rise in prolactin. 

Stahel RA, Oelz O. Syndrome of inappropriate ADH secretion secondary to vinblastine. Cancer Chemother Pharmacol 1982 8(2) 253-4. 

Diazepam has been reported to cause inappropriate ADH secretion in a neonate (28). 

Vincristine Tissue damage with extravasation Peripheral neuropathy alopecia mild bone marrow depression constipation paralytic ileus jaw pain inappropriate ADH secretion optic atrophy... 

Severe water intoxication caused by inappropriate ADH secretion has been described in an elderly woman taking indometacin (SEDA-17,108). 

Cisplatin-induced nephrotoxicity can be detected by a rise in blood urea or by a fall in creatinine clearance. Tubular dysfunction can cause hyponatremia (72), hypokalemia, hypomagnesemia (173), and hjrpophosphatemia. Inappropriate ADH secretion may be partly responsible for hjrponatremia (191). 

Bone marrow depression alopecia hemorrhagic cystitis sterility (may be temporary) pulmonary infiltrates and fibrosis hyponatremia leukemia bladder cancer inappropriate ADH secretion cardiac toxicity amenorrhea... 

In hypoosmotic hyponatremia with a normal volume status, the most common etiologies are the syndrome of inappropriate ADH (SIADH), primary polydipsia, hypothyroidism, and adrenal insufficiency (see Figure 46-2). SIADH is usually a result of ectopic or otherwise inappropriate ADH production arising from a variety of conditions (see Chapters 45 and 50) and results in excessive H2O retention. SIADH is often diagnosed when a urine osmolality that is greater than plasma osmolality (usually by more than >i00 mOsmol/kg) is observed in the setting of hyponatremia, but only when renal, adrenal, and thyroid functions are normal. Hypothyroidism impairs free H2O excretion, whereas in adrenal insufficiency, Na" is lost in preference to IC reabsorption. Finally, euvolemic hyponatremia can be... 

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