1. Low salt
BM 2019
MMC

2.
Nausea
Malaise
< 120
Headache
Lethargy
Obtundation
Siezure
Coma
Chronic  less severe
Chronic adaptation important  CSF , K loss and then organic solutes  24 hours

3. CSF Nausea Malaise Headache Lethargy Seizures Coma
Respiratory depression
The adaptive process takes 24 hours
The correct of organic solute concentration is much slower and rapid correct  osmotic demyelination especially in premenopausal women and children
Cell water K+
Organic solutes (1/3)
CSF

4. 5.2 vs 1.3% @ 30 days 1.8% vs 0.7% 7.4% vs 4.6% 3.7% vs 1.5%
75000 hyponatreamia normal
5.2 vs 30 days
1.8% vs 0.7%
7.4% vs 4.6%
3.7% vs 1.5%

7. 8 – 10 mmol/L in
24 hours
18 in 48 hours

8. Primary Polydipsia overwhelms kidney

10. Serum osmolarity and sodium concentration in plasma water is normal
The sodium concentration per litre of plasma is reduced
Asymptomatic = tonicity is maintained
Tonicity maintained = sodium per Liter of plasma is reduced (but normal per liter of plasma water)

11. Glucose increases serum osmolarity and is an effective osmole ( i
Glucose increases serum osmolarity and is an effective osmole ( i.e it doesn’t freely enter cells)
Water moves into plasma and dilutes sodium
Neurologic symptoms not from low sodium
For ethanol / urea  ineffective but some contribution
Patients with hyponatreamia in these patients as likely to develop symptoms

12. Severe hypertonic hyponatreamia due to dilution

13. Symptom Severity Acute or Chronic Mild Moderate Severe < 120 mEq/L
hours
Symptom Severity
Seizures Obtunded Coma Respiratory Arrest

14. Hypotonic hyponatremia
Hypovolemia
Oedematous
Low urine Na < 25
Low urine Na > 40
GIT loss
‘Third space’
Diuretics
Urine Chloride >25
Diuretics
Primary adrenal insufficiency
‘Cerebral salt wasting’
Urine chloride < 25
Vomiting
Associated M. Alk
Heart failure
Cirrhosis
End stage renal disease

15. Euvolemic Hypotonic hyponatremia High urine sodium > 40
High urine osmolality > 100
Low urine sodium < 25
Low urine osmolality < 100
SIADH
Primary polydipsia
Beer potomania
Rapid correct of hypovolemia with saline
Reversal of SIADH after stopping drug
GC replacement in adrenal insufficiency
Surreptitious diuretic use
Severe hypothyroidism
Cortisol deficiency

16. Chlorpropamide Carbamazepine Oxcarbazepine IV cyclophosphamide SSRI
Vincritine
Haloperidol
Valproate
NSAIDS
Alpha interferon
Amiodarone
MTX
opiates
CNS
Stroke
Bleed
Tumour
Infection
Trauma
Psychosis
Malignancy
Lung Small cell

17. < 105
Hypokalemia
Alcoholism
Malnutrition
Liver disease
Premenopausal women
Young children

18. 6/6 8/24 ABC Stop offending drugs Reverse the cause
Treat hypovolemia with saline or 3% saline if severe
Treat seizures with benzo
8/24
8-10 mEq/L in 24 hours
Acute Severe:
4-6 mEq/L will reverse most severe symptoms in 6 hours
50-100ml aliquots of 3% Saline over 10 minutes
Max 300mls
6/6