SIADH: Treatment, symptoms, advice & help
SIADH is Syndrome of inappropriate antidiuretic hormone secretion: This is a condition in which an endogenous source of ADH ( cerebral or tumour derived) promotes water retention in the kidneys .This leads to volume overload and fall in serum sodium levels.
SIADH: Incidence, age and sex
The incidence varies with the various causative factors.
Signs and symptoms of SIADH: Diagnosis
The symptoms are due to low serum sodium levels and are non-specific .They include confusion, nausea, altered mood, seizures and loss of consciousness.
Low plasma sodium concentration (typically < 130 mmol/l), low plasma osmolality (< 270 mmol / kg), urine osmolality > 150 mmol / kg, urine sodium concentration 30 > mmol / l are suggestive of the diagnosis.
Causes and prevention of SIADH
Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is caused endogenous production of ADH by a) tumours, especially small – cell lung cancer b)CNS disorders like stroke, trauma ,infection and pscychosis c) pulmonary disorders pneumonia and tuberculosis, d) drugs like anticonvulsants, , Psychotropics, Antidepressants, Cytotoxics, Hypoglycaemics, and Opiates e)sustained pain, stress, nausea.
The common complications include water overload which can cause cerebral overload, hypouricemia which may increase the risk of exercise-induced renal failure, hypochloremia which may cause severe vomiting, severe diarrhea, nausea, decreased appetite, confusion, and irritability, low osmolarity and hypokalemia which can cause arrythmias, muscular weakness, and muscle cramps. With severe hypokalemia, tetany, and respiratory depression can occur. High concentration of sodium in the urine increases the risk for urinary tract infections because the solute is very concentrated.
Specific treatment measures should be related to the underlying cause. Fluid restriction should be in the range 600 – 1000 ml / day. Where an inadequate rise in plasma Na results, treatment with demeclocyline (600 – 900 mg / day) may enhance water excretion, by interfering with collecting duct responsiveness to ADH. An effective alternative for subjects with persistent hyponatraemia due to prolonged SIADH is oral urea therapy (30 – 45 g / day), which provides a solute load to promote water excretion.