Hyponatremia SIADH Treatment
Normal serum Na 135-145 mEq/L
Definition
mild hyponatremia 130 – 134 mEq/L
moderate hyponatremia 125 – 129 mEq/L
Severe hyponatremia less than 125 mEq/L
Causes of SIADH
PULMONARY- Pneumonia tuberculosis and Empyema, tumors like small cell carcinoma of lung
CNS- CVA, SAH, SDH and Meningitis, GBS, acute psychosis, head trauma, Brain Tumor, encephalitis
Nausea, pain, post operative, stress AIDS, acute intermittent porphyria
Drugs – cyclophosphamide, vincristine, vinblastine, desmopressin vasopressin(ADH) amiodarone, SSRIs, monoamine oxidase inhibitors, carbamazepine, tricyclic antidepressants etc..
Diagnosis of SIADH
Decreased serum Na+, level serum urea, creatinine and Uric acid
decreased serum osmolality
Increased urine Na (>20 mEq/L)
No edema or dehydration clinically
Normal Thyroid and adrenal functions.
- Correct the electrolyte imbalance only if the patient is symptomatic or when serum Na < 120mEq/L
- Symptoms depend upon speed of development of hyponatraemia. Hence slowly developing gross hyponatraemia can be asymptomatic.
Hyponatremia SIADH Treatment
I. Water restriction to 500-800ml/day
2. Treatment of underlying causes and withdraw offending drugs like –
Oral hypoglycaemics (tolbutamide, chloropropamide) Anticancer drugs (vincristine, cyclophosphamide). CNS drugs (haloperidol, carbamazepine, trycyclic antidepressants)
3. Increase dietary salt intake up to 15gm/day and increase in protein intake.
4. Correction with hypertonic saline If patient is drowsy or unconscious. 3.0 % saline Ideally correct to 130mEq/L
* Calculation of deficit – Formula 1 (Sodium deficit in mEq) x (0.6) x (body weight in kg)
Correct 50% of the calculated deficit with 3% saline (rate of correction: to increase the plasma Na+ by 1-2 mEq/hour) or up to 8 mEq/liter for the first 24 hours.
Saline strength
1 litreLof 3 % Saline 517 mEq, that has to be given at a rate which increases plasma Na” by 1-2mEq/L hour. (i.e., over 15 hours in the above example)
If correction is done very fast, it can result in central pontine myelinolysis.
Increase salt intake in food, limit water intake
5. Inj. Frusemide it increases clearance of water. 20mg IV stat can be given
6. K+ supplementation may be required if hypokalaemia present
7. In chronic cases – Demeclocycline can be given PO 600mg/day in 2-3 divided doses.
8. In all resistant cases, rule out hypothyroidism or hypoadrenalism.
DILUTIONAL HYPONATRAEMIA
As in various conditions associated with oedema.
Patient may be oedematous.
Serum is hypoosmolar.
Restrict water and salt.
More water restriction than salt restriction.
Give loop diuretics.
Correct associated hypokalaemia.
Treatment or correction of underlying cause
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