This document discusses disorders of water and sodium balance. It begins by introducing concepts of water and sodium regulation including total body fluid volume, distribution between intracellular and extracellular compartments, and mechanisms like ADH, renin-angiotensin-aldosterone system, and natriuretic peptides. It then summarizes edema, alterations in isotonic fluid volume including deficit and excess, and alterations in sodium concentration covering hyponatremia and hypernatremia. For each condition, it outlines definitions, causes, manifestations, and treatment approaches.

1. Disorders of water and sodium
balance
Alireza soleimani
Professor of nephrology
Pathophysiology

2. Outline
Introduction of water and sodium balance
Edema
Alterations in isotonic fluid volume
• isotonic fluid volume deficit
• isotonic fluid volume excess
Alterations in sodium concentration
• hyponatremia
• hypernatremia

3. Introduction of water and sodium
balance

4. Water and sodium balance
Total fluid volume and distribution
Body fluid composition
Osmolality of the body fluid
Water balance
Mechanisms of regulation of body fluid
and sodium balance

5. Total fluid volume and distribution
Total body fluid accounts for 60% of body
mass in males.
Total body fluid is mainly distributed in
intracellular and extracellular compartments
 Intracellular fluid ( ICF) : 40%
 Extracellular fluid (ECF): 20%
 Interstitial fluid: 15%
 Plasma: 5%

6. Body fluid composition
The ICF is separated from the ECF by a
selective cell membrane that is only
permeable to a limited number of
substances such as water, oxygen and
carbon dioxide, but not to most of the
electrolytes in the body.
The concentration of ions in the
interstitial fluid and plasma are
considered to be equal except for
protein.

7. Osmolality of the body fluid
The total osmolality is almost equal among
plasma, the interstitial and intracellular fluids
with a range from 280-310 mOsm/L, due to a
free permeability of cell membrane to water.
Nearly 80% of the osmolality of plasma and
the interstitial fluid is induced by sodium and
chloride ions. And approximately half of the
intracellular osmolality is caused by
potassium.

8. Water balance
Water intake
• Ingestion in the form of liquid and water in food:
2100ml/day
• Metabolism in the body following the oxidation of
carbohydrates: 300ml/day
Water output
• Insensible evaporation from respiratory tract and
through the skin: 700ml/day
• Sweating: 100ml/day
• Feces: small amount
• Urine: 1500ml/day

9. Mechanisms of regulation of body fluid
and electrolyte balance
Sensation of thirst
Antidiuretic hormone (ADH)
Renin-angiotensin-aldosterone system
natriuretic peptide (NP)

10. ADH
Main target sites: distal tubules and
collecting ducts in kidney
Function: to Promote the water
reabsorption and cause increased ECF
volume and decreased urinary output.
Stimulating factors:
• Blood pressure↓
• Plasma osmolality↑
• Blood volume ↓

11. Renin-angiotensin-aldosterone system
Arterial pressure ↓
Plasma sodium content↓
Sympathetic nerve ↑
Glomerulus
(juxtaglomerular cells)
renin
Angiotensin I Angiotensin II
Angiotensin converting enzyme
aldosterone
Renal retention of sodium
Increase potassium secretion
ECF volume ↑
Arterial pressure↑
Adrenal gland

12. NP
ANP is a hormone produced by specific cells of
cardiac in response to blood volume expansion.
Function: NP inhibits the reabsorption of
sodium and water by the renal tubules, which in
turn increases urinary excretion and helps to
return blood volume back toward normal.
NP exerts a negative regulation against ADH in
the central nervous system.

13. Edema

14. Definition of edema
Edema can be defined as palpable
swelling produced by expansion of the
interstitial fluid volume.
Edema is caused by excessive fluid in
the interstitial compartment.

15. Causes and pathogenesis of edema
 Increased capillary filtration pressure
 Decreased capillary colloidal osmotic
pressure
 Increased capillary permeability
 Obstruction to lymph flow

16. Increased capillary filtration pressure
Increased vascular volume
• heart failure
• kidney disease
• pregnancy
Venous obstruction
• liver disease with portal vein obstruction
• venous thrombosis

17. Decreased capillary colloidal
osmotic pressure
Increased loss of plasma proteins
• protein-losing kidney diseases
• extensive burns
Decreased production of plasma
proteins
• liver disease
• starvation
• malnutrition

18. Increased capillary permeability
Inflammation
Allergic reaction
Malignancy
Tissue injury and burns

19. Obstruction to lymph flow
Malignant obstruction of lymphatic
structures
Surgical removal of lymph nodes

20. Manifestations of edema
Life threatening in some locations,
such as brain, larynx, lungs.
Interfering with movement and limiting
joint motion.
Increasing the distance for diffusion of
oxygen, nutrients and wastes at the
tissue level.

21. Treatment of edema
Correcting or controlling the cause , and
preventing tissue injury
Diuretic therapy
Elastic support stockings and sleeves for
patients with lymphatic or venous
obstruction
Administering albumin intravenously to raise
the colloidal osmotic pressure when edema
is caused by hypoalbuminemia.

22. Alterations in isotonic fluid
volume

23. Alterations in isotonic fluid volume
Isotonic fluid volume disorders
represent an expansion or contraction
of the ECF brought about by
proportionate changes in both sodium
and water.
Two types:
• Isotonic fluid volume deficit
• Isotonic fluid volume excess

24. Isotonic fluid volume deficit
Definition:
Isotonic fluid volume deficit results
when water and sodium are lost in
isotonic proportions
Causes:
• Inadequate fluid intake
• Excessive fluid losses

25. Inadequate fluid intake
Oral trauma or inability to swallow
Inability to obtain fluids
Impaired thirst sensation
Therapeutic withholding of fluids
Unconsciousness or inability to
express thirst

26. Excessive fluid losses
Excessive gastrointestinal fluid losses
vomiting, diarrhea, gastrointestinal suction
Excessive renal losses
diuretic therapy, osmotic diuresis, adrenal
insufficiency
Excessive skin losses
fever, exposure to hot environment, burns and
wounds that remove skin
Third-space losses
intestinal obstruction, edema, ascites

27. Manifestations of isotonic fluid
volume deficit
Acute weight loss
Compensatory increase in ADH
Decreased extracellular fluid volume
Shock

28. Treatment of isotonic fluid volume
deficit
Treating the underlying causes
Using isotonic electrolyte solutions for
replacement.

29. Isotonic fluid volume excess
Definition:
It represents an isotonic expansion of
the extracellular fluid compartment.
Water and sodium are increased in
isotonic proportions.
Causes:
• Inadequate sodium and water elimination
• Excessive sodium and water intake

30. Inadequate sodium and water
elimination
Congestive heart failure
Renal failure
Hyperaldosteronism
Liver failure

31. Excessive sodium and water intake
Excessive sodium intake
Food, sodium containing medications or fluid
Excessive fluid intake
• ingestion of fluid in excess of output
• administration of fluids or blood at an
excessive rate

32. Manifestations of isotonic fluid
volume excess
Acute weight gain
Increased interstitial fluid volume
Dependent and generalized edema
Increased vascular volume

33. Treatment of isotonic fluid volume
excess
Sodium-restricted diet
Diuretic therapy is commonly used to
increase sodium elimination.

34. Alterations of sodium
concentration

35. Alterations of sodium concentration
• Hyponatremia
• Hypernatremia

36. Hyponatremia
• Definition
Hyponatremia represents a decrease in
plasma sodium concentration below
135 mmol/L.

37. Causes of hyponatremia
Excessive sodium losses and
replacement with sodium-free water
Excessive water intake in relation to
output

38. Excessive sodium losses and
replacement with sodium-free water
Exercise- or heat-induced sweating
Gastrointestinal losses
Renal losses (some chronic renal
diseases)

39. Excessive Water Intake in Relation
to Output
Excessive administration of sodium-
free solutions
Repeated irrigation of body cavities
with sodium-free solutions
Irrigation of gastrointestinal tube with
distilled water
Kidney disorders that impair water
elimination
Increased ADH level

40. Manifestations of hyponatremia
Signs Related to Hypo-osmolality of
Extracellular Fluids and Movement of Water
Into Brain Cells and Neuromuscular Tissue
Muscle cramps, Weakness, Headache, Depression,
Personality changes, Lethargy and coma
Gastrointestinal Manifestations
Anorexia, nausea, vomiting, Abdominal cramps,
diarrhea

41. Treatment of hyponatremia
water intoxication
 Limit water intake
 Administer diuretics
sodium deficiency
Administer saline solution orally or
intravenously

42. Hypernatremia
• Definition
Hypernatremia implies a plasma
sodium level above 145 mmol/L.

43. Causes of hypernatremia
Excessive Water Losses
Decreased Water Intake
Excessive Sodium Intake

44. Excessive water losses
Watery diarrhea
Excessive sweating
Hyperventilation
Decrease level of ADH

45. Decreased Water Intake
Unavailability of water
Oral trauma or inability to swallow
Impaired thirst sensation
Withholding water for therapeutic
reasons
Unconsciousness or inability to
express thirst

46. Excessive Sodium Intake
Rapid or excessive administration of
sodium-containing solutions

47. Manifestations of hypernatremia
Thirst and signs of increased ADH levels
Oliguria or anuria
Intracellular dehydration
– Dry skin and mucous membranes
– tongue rough and fissured
– decreased salivation
Signs related to hyperosmolality of ECF and
movement of water out of brain cells
– Headache, agitation and restlessness, seizure and coma

48. Treatment of hypernatremia
Treating the underlying causes of the
disorder
Fluid replacement therapy to treat the
accompanying dehydration.

49. Today you learned:
How to regulate the normal water and
sodium balance?
Definition, causes, manifestations and
treatment of the following pathological
conditions
• Edema
• Isotonic fluid volume deficit
• Isotonic fluid volume excess
• Hyponatremia
• hypernatremia