****** HELP ******( SIADH )Inappropriate secretion of ADH leads to retention of water and hence dilutional hyponatraemia.
Clinical features:these are usually vague
*confusion
*nausea
*irritability
*fits and comma in later stages.
Mild symptoms usually occur with plasma sodium levels below 125 mmol/L and serious manifestations are likely below 115 mmol/L.
Diagnosis:*dilutional hyponatraemia due to excessive water retention
*low plasma osmolality with higher 'inappropriate' urine osmolality
*continued urinary sodium excretion >30mmol/L
*absence of hypokalaemia (or hypotension)
*normal renal and adrenal and thyroid function.
Treatment:*fluid intake should be restricted to 500-1000 mL daily, if tolerated, this will correct the biochemical abnormalities in almost every case.
*plasma osmolality and sodium and body weight should be measured frequently.
*if water restriction is poorly tolerated or ineffective, demethylchlortetracycline (600-1200 mg daily) may be given; this inhibits the action of vasopressin (ADH). It may, however, cause photosensitive rashes.
*when the syndrome is very severe, rarely hypertonic saline (300 mmol/L slowly i.v.) is given and frusemide may be given. These tearments are potentially dangerous and should only be used with extreme caution.
