Sodium imbalance can cause hyponatremia or hypernatremia. Hyponatremia is defined as a serum sodium level below 135 mmol/L and can be caused by conditions that decrease sodium levels like diuretic use. Hypernatremia is a serum sodium over 145 mmol/L due to inadequate sodium retention. Both conditions require slow correction to avoid complications like osmotic demyelination syndrome from overly rapid changes. Proper treatment depends on the severity and chronicity of the sodium imbalance.

1. Sodium Imbalance
Dr Mohammad Yasin
Diploma(Endocrinology and Metabolism)
BIRDEM General Hospital

2. Basic daily requirement
Sodium: 1.5-2 mmol/kg
( 105-140 mmol/day in 70 kg adult)
Ref: Davidson’s Principles & Practice of Medicine

3. Ref: Davidson’s Principles & Practice of Medicine

4. Disorder in Sodium Balance
A.Hyponatremia
B. Hypernatremia

5. A. Hyponatraemia:
Hyponatraemia is defined as a serum
Na< 135 mmol/L
Severity Serum Sodium Symptoms
Mild 130-135 mmol/L None
Moderate 125-129 mmol/L Nausea, Delirium,
Headache
Severe < 125 mmol/L Vomiting,
Somnolence,
Seizures, Coma,
Cardiorespiratory
arrest

6. Causes of Hyponatremia
Volume status Examples
Hypovolaemic
.Renal sodium losses:
.Diuretic therapy (Especially
thiazides)
.Adrenocortical failure
.Gastrointestinal losses:
.Vomiting .Diarrhoea
.Skin Losses: Burns

7. Volume status Examples
Euvolaemic
. Primary polydipsia
. Excessive electrolyte -free water infusion
. SIADH
. Hypothyroidism
Hypervolaemic
. CCF . Cirrhosis
. Nephrotic syndrome
. CKD(Free water intake)
Ref: Davidson’s Principles & Practice of Medicine

8. Ref: Davidson’s Principles & Practice of Medicine

9. Diagnostic criteria of SIADH :
. Low plasma Sodium Conc.( Typically <130 mmol/L)
. Low plasma osmolarity (<275 mOsmol/kg)
. Urine osmolarity not minimally low
(typically >100 mOsmol/kg)
. Urine sodium conc. not minimally low
(>30 mmol/L)

10. • Diagnostic criteria(Cont.):
. Low-normal plasma urea, creatinine, uric acid
. Clinical Euvolaemia
. Absence of adrenal, thyroid, pituitary or renal
insufficiency
. No recent use of diuretics
. Exclusion of other causes of hyponatremia
. Appropriate clinical context
Ref: Davidson’s Principles & Practice of Medicine

11. Approach to Hyponatremia

12. Cont.
Ref: Davidson’s Principles & Practice of Medicine

16. Ref: Davidson’s Principles & Practice of Medicine

17. *** That’s why rate of correction of plasma Na
concentration in chronic asymptomatic
hyponatremia should not exceed 10 mmol/L/24
hrs and a slower rate is generally safer.

18. B. Hypernatremia
Hypernatremia is defined as serum sodium
> 145 mmol/L.
Pathophysiology:
-- Failure to generate an adequate medullary
concentration gradient in kidney due to low
GFR or loop diuretic therapy or,
-- Failure of vasopressin system
(Cranial/ Nephrogenic Diabetes Insipidus)
Ref: Davidson’s Principles & Practise of Medicine

19. Figure:Etiologies of Hypernatremia Ref:Oxford handbook of Nephrology

20. Causes of Hypernatremia

21. Clinical feature:
. Generally this patients have reduced cerebral
function which result in dehydration of neurons &
brain shrinkage
. Usually as this patients have intact thirst
mechanism, hypernatremia may not progress far
. If protective mechanism is impaired sequence of
events may occur:
Weakness, Delirium, Dizziness ComaDeath
Ref: Davidson’s Principles & Practise of Medicine

22. Management
• Treatment of Hypernatremia depends on
-- Rate of development
-- Underlying cause

23. • If the condition has developed rapidly relatively
rapid correction may be attempted because
there may be acute neuronal shrinkage
This can be achieved by infusing isotonic 5%
Dextrose or hypotonic 0.45% Normal saline

24. • In older patients, it is likely that the disorder
has developed slowly and extreme caution is
required in lowering plasma sodium to avoid
the risk of cerebral oedema
• If possible the underlying cause should be
addressed irrespective of the fact that
whether it is acute or chronic
Ref: Davidson’s Principles & Practise of Medicine

25. Sodium Correction formula
** Na deficit=0.6 Weight(kg) (desired Na-actual Na)
(In case of female use 0.5)
** Change in serum Na with 1 L infusate
Infusate Na- Serum Na
Total Body Water+ 1
Ref: Davidson’s Principles & Practise of
Medicine

26. Pseudohyponatremia
• It is a condition where serum Na+ is < 135
mmol/L but serum Osmolarity is normal(280-
300 mOsm/kg)
• Occurs dur to presence of osmotically active
substance in plasma leading to intracellular
shift of Sodium

27. Cont.
• Causes:
-- Severely elevated levels of cholesterol
-- Abnormally high levels of protein in
conditions such as . Chronic infectious
disease(Hepatitis C, HIV etc) . Multiple
Myeloma . Malignant lymphoproliferative
disorder . Heavy/ Light chain disease . IV IG
therapy
-- Hyperglycemia
Ref: Oxford Handbook Of Nephrology

28. Osmotic Demyelination Syndrome
• Also known as central pontine myelinolysis
• Causes:
-- Overly rapid correction of Hyponatremia
(Most common)
-- Hypokalemia
-- Burn victims
-- Patients on dialysis
-- Anorexia nervosa(when feeding is started)

29. Cont.
• Symptoms:
Initially patient may have features related to
hyponatremia( Nausea, Vomiting, Confusion,
Headache, Seizure etc.) These symptoms may
subside with normalization of serum Na+ 3-5 days
later patient may present with Gait disturbance,
Decreased consciousness level, Seizure, difficulty in
respiration etc.
• Signs:
Progressive development of
-- Spastic quadriparesis
-- Pseudobulbar palsy
-- Emotional lability etc.

30. Cont.
• Risk factors:
-- Liver cirrhosis
-- Liver transplant
-- Alcoholism
-- Malnutrition
-- HIV
-- Hyperemesis gravidarum etc.

31. Cont.
• Treatment:
-- Once osmotic demyelination has begun,
there is no cure or specific treatment
-- Care is mainly supportive
-- Alcoholics should have vitamin supplement
Factors favoring favourable outcome:
-- Concurrent treatment of all electrolyte
imbalance
-- Early ICU involvement
-- Early introduction of feeding including
thiamine supplement
Ref:Harrison’s Nephrology

32. TAKE HOME MESSAGE
• During evaluation of sodium imbalance
volume status of the patient must be
perceived
• In treating acute severe hyponatremia a rapid
approach should be made but the rate of
cooection must not exceed 10 mmol/day
• Acute hypernatremic cases should be treated
rapidly to prevent acute neuronal shrinkage