2. SODIUM METABOLISM
INTAKE
BODY DISTRIBUTION
LOSES100 -300 mmoles/DAY
Bones and tissues
25%
Exchangeable
75%
ECF
ICF
Interstitial fluid
Renal = IntakeRenal = Intake
Faeces
5mmoles/day
Sweat
5mmoles/day
Normal level of Na+ in plasma is 136-145 mEq/L
and in cells 12 mEq/L.
Sodium is the major cation of extracellular fluid
Dr. N. Sivaranjani 2
3. • Functions of sodium
• Maintenance of resting membrane potential
• Nerve impulse transmission
• Muscle contraction
• Maintenance of EC osmotic pressure and Water balance
• Regulation of A-B balance
• Glucose , galactose, amino acid absorption
• Functioning of NaK ATPase and Na-H exchanger.
Dr. N. Sivaranjani 3
4. Regulation of sodium balance
• Kidney plays a predominant role.
• Renin/angiotensin – Aldosterone mechanism
effective circulating volume is the major stimulus
• Atrial Natriuretic peptide
increase in ECF, increase BP - stimulus
Dr. N. Sivaranjani 4
5. Disorders of sodium balance
• Hyponatremia
• Abnormally low serum sodium <136 mEq/L
• Decrease in plasma osmolality
Clinical features :
Hyponatremia –due to excess H2O & Na :-
Edema , ascites , increased JVP
Hponatremia - due to loss of Na & H2O :-
Decreased skin turgor , dry mucus membrane, hypotension and tachycardia.Dr. N. Sivaranjani 5
6. HYPONATREMIA
Hypervolemia
Excess of H2O & Na retention
Presents with Edema
PSEUDOHYPONATREMIA
RENAL loss
SALT LOSING NEPHROPATHY
ADDISONS DISEASE
Diarrhea
Vomiting
Burns
SIADH
CCF
NEPHROTIC SYNDROME
CIRRHOSIS
HYPERLIPIDEMIA
HYPERPROTEINEMIA
Hyponatremia
N or raised P.Osmolality
plasma water fraction
falls
TRUE HYPONATREMIA
ATN
Euvolemia
Excess of H2O
NO Edema
Increased intake of water –
PSYCHOGENIC POLYDIPSIA
IATROGENIC FLUID OVERLOAD
Hypovolemia
H2O & Na loss
Dehydration
NON RENAL
loss
Dr. N. Sivaranjani 6
7. Diagnostic approach
• Plasma Na – decreased
• Plasma osmolality – decreased
• If pt Dehydrated – due to loss of Na and H2O
• Not dehydrated – due to excess Na and H2O
• Urine Na –
• Renal loss more than 20 mEq/L
• Non renal loss less than 10 mEq/L
Dr. N. Sivaranjani 7
8. 8
Treatment of Hyponatremia
• Treat the underlying cause
• Administered sodium should be closely monitored
• Fluid restriction and diuretics – edematous state
Dr. N. Sivaranjani
9. 9
Hypernatremia
– Plasma Na+ > 145 mEq / L
– Total body Na Content is high with respect to water
– Common cause – excessive water loss - Cells dehydrate
C/F :-
If Hypernatraemia is due to water loss-
symptoms of Dehydration
Intense thirst, mental confusion, fever & decreased urine output
Due to excess salt gain- Hypertension ,Edema
Dr. N. Sivaranjani
10. CAUSES OF HYPERNATREMIA
Water depletionRetention of sodium
GIT loss
S.Vomiting S.Diarrhea
Excessive sweating
Ch.Fever S.ExerciseDI
Hypothalamic
Nephrogenic
Ingestion
Infusion of Na HCO3
for treatment of acidosis
1̊ Hyperaldosteronism
Conn’s syndrome
Cushing’s syndrome
Na & H2O depletion
Decreased intake Increased loss
Unconscious
patient
Diuretic therapy ,
nephropathy ,
polyuric phase of
ATN ,
DM
Dr. N. Sivaranjani 10
11. • Diagnostic approach
• Serum sodium and osmolality – elevated
HYPERNATREMIA
Urine osmolality
>300 mOsmo/Kg
Diarrhea – 700 mOsmol/Kg
Excessive sweating
DM – Osmotic diuresis
< 300 mOsmo/Kg
Diabetes insipidusADH stimulation
No response
Nephrogenic DI
Response
Central DI
Dr. N. Sivaranjani 11
12. 12
Treatment of Hypernatremia
• Treat the underlying cause
• Correct the free water deficit at a rate of 1mEq/L/hr
• Check serum Na every 4hr
• Use isotonic salt -free IV fluid
• acute hypernatremia - correction can be quicker.
• chronic cases should be treated slowly to prevent cerebral edema
Dr. N. Sivaranjani
13. POTASSIUM METABOLISM
INTAKE
BODY DISTRIBUTION
LOSES30 -100 mmoles/DAY
ECF
55 MMOLES/L
ICF
3600 MMOL/L
Renal
20-100 MMOL/L
Faeces
5mmoles/day
LOSS
Normal level of K+ in plasma is 3.5-5 mEq/L
and in cells 150 mEq/L.
Dr. N. Sivaranjani 13
14. Functions of potassium
• Nerve impulse transmission
• Maintenance of IC osmotic pressure
• Function of H-K ATPase and HCL secretion
• Activation of intracellular enzyme- PK, GS
• Cardiac muscle activities
• Neuromuscular excitability
Dr. N. Sivaranjani 14
15. Uptake of K into cells - Na K ATPase / pump
Renal regulation K balance – 67% reabsorbed by PCT H+-K ATPase
Aldosterone – increase excretion of K+ from DCT
High K diet, H+ – increases the excretion of K.
Regulation of plasma Potassium
Increase uptake of K into cell Decrease uptake of K
Insulin DM
Alkalosis Acidosis – H+
Beta adrenergic stimulation Alpha Adrenergic stimulation
Inhibition of Na K ATPase
Dr. N. Sivaranjani 15
17. 17
Hypokalemia
• Serum K+ < 3.5 mEq /L
• Beware if diabetic
– Insulin pushes K+ into cells
– D.Ketoacidosis – H+ replaces K+, which is lost in urine
Dr. N. Sivaranjani
18. HYPOKALEMIA
Intake Altered
cellular
uptake
GI loss
Renal loss
Alkalosis
Insulin
Renal Tubular acidosis
Hyper Aldosteronism –
Cushing’s disease
Dietary
deficiency
Diuretics
Vomiting
Diarrhea
GI fistula
Hypokalemic periodic
paralysis
(abnormal calcium channels)
Dr. N. Sivaranjani 18
19. 19
Clinical manifestations of Hypokalemia
Non specific symptoms - Anorexia, Nausea, Vomiting ,Muscle cramps,
confusion.
• Neuromuscular disorders
– Weakness, decreased reflexes.
– ECG - appearance of U wave , Flat or inverted T wave, ST
segment depression. Arrhythmias and cardiac arrest
Rx- supplement K+ slowly, preferably by foods
Be cautious in administering drugs that are not potassium-sparing
Monitor acid-base balance, pulse, BP and ECG
Dr. N. Sivaranjani
21. 21
Hyperkalemia
• Serum K+ > 5.5 mEq /L
• Beware of diabetic
– Insulin deficiency pushes K+ outside cells.
Dr. N. Sivaranjani
22. HYPERKALEMIA
Intake Pseudo hyperkalemia
Altered Cellular Uptake
Renal Excretion
Acidosis
Insulin deficiency
Renal failure
Hypo Aldosteronism –
Addison’s disease
HemolysisK rich food –
banana
,orange Leukocytosis
Thrombocytosis
Factitious (K+ leaches out when
blood is kept for a long time
before separation
Dr. N. Sivaranjani 22
23. 23
Clinical manifestations of hyperkalemia
• Early – hyperactive muscles , paresthesia
• Late - muscle weakness, flaccid paralysis
ECG – wide QRS complex, Peaked T-waves, Prologed PR interval.
• Dysrhythmias
– Bradycardia, heart block, cardiac arrest
Dr. N. Sivaranjani
26. Treatment
Acute treatment –
• Infusion of Ca. gluconate – antagonize K
• Insulin and glucose administration – enhance entry of K into cell
from plasma
• Administration of HCO3 – correct acidosis
Chronic treatment –
• Administration of K binding resins orally
• Dialysis – hemodialysis and peritoneal dialysis.
Dr. N. Sivaranjani 26
27. Cl ˉ (Chloride)
• Major extracellular anion
• Plasma conc. 95 -105 mEq/ L
Regulation in kidney through:
• Reabsorption with sodium
• Reciprocal relationship with bicarbonate
Dr. N. Sivaranjani 27
28. Functions of chloride
• Regulation of A-B balance, Water balance and osmotic
pressure
• Formation of HCl
• Chloride shift
• Enzyme salivary amylase is activated by Cl.
Dr. N. Sivaranjani 28
29. • Most commonly from gastric losses
– Excessive vomiting - compensatory increase in plasma
bicarbonate. This is called hypochloremic alkalosis
– Excessive sweating.
• Renal loss
- Addisons disease, salt losing nephropathy .
• Often presents as a contraction alkalosis with paradoxical
aciduria (Na+ retained and H+ wasted in the kidney)
Rx: resuscitation with normal saline
Hypochloremia
Dr. N. Sivaranjani 29
30. • Dehydrtaion ,
• Cushing’s synd,
• Severe diarrhea - loss of bicarbonate and compensatory
retention of chloride.
• Renal tubular acidosis.
• often presents as a hyperchloremic acidemia with paradoxical
alkaluria (H+ retained and Na+ wasted in the kidney)
Rx: stop normal saline and replace with hypotonic crystalloid
Hyperchloremia
Dr. N. Sivaranjani 30
31. IV FLUID REPLACEMENT THERAPY
Indications
Replacement of abnormal fluid & electrolyte losses
[surgery, trauma, burns, GI bleeding]
Maintenance of daily fluid & electrolyte needs
Correction of fluid disorders
Correction of electrolyte disorders
Dr. N. Sivaranjani 31
32. Assessment of fluid compartment
Plasma volume –
• BP, JVP, Pulse rate, CVP central venous
pressure
Interstitial volume –
• Edema
Intracellular volume –
• Difficult to assess clinically
• Disorders of cerebral function is
important
Dr. N. Sivaranjani 32
33. What fluids to give :
5% dextrose – replace deficit in total body water
0.9% sodium chloride – expands only ECF volume
Hypotonic - Water moves from ECF to ICF by osmosis
Usually maintenance fluids
0.45% sodium chloride
0.33% sodium chloride
Hypertonic – expands and rise osmolality of ECF
3% NaCl
Dr. N. Sivaranjani 33
34. Plasma Expanders
• Stay in vascular space and increase osmotic pressure
• Colloids (protein solutions)
– Packed RBCs
– Albumin
– Plasma
Dr. N. Sivaranjani 34
35. Essay (15)
What are the functions of Na in the body? What is the reference range for
levels of serum Na. describe working of RAA system o maintain optimal
amounts of sodium in the body. Briefly disorders associated with
derangements in Na homeostasis.
Short notes (5)
Water toxicity
Dehydration
Give an account of water distribution and its balance in the body
Explain the metabolic inter relation b/w Na conc and water volume.
Hyponatremia
Very short notes (2)
Normal Na and K level
Name the major intra and extra cellular anion
Osmolality Dr. N. Sivaranjani 35
