This document discusses water and electrolyte metabolism. It covers topics such as the distribution of total body water and intracellular/extracellular fluid volumes. It describes water turnover rates and the hormones that regulate electrolyte and water balance, including ADH, aldosterone, renin-angiotensin system, and atrial natriuretic peptide. Disturbances in water and electrolyte homeostasis like dehydration, water intoxication, and disorders of potassium, sodium, and chloride are explained. Analytical methods for measuring electrolytes are also briefly mentioned.
2. Distribution of water
total body water (42 ltr) (60% of body weight)
ICF (28 ltr) (40% BW) ECF (14 L)(20% BW)
IV(plasma) extravscular
(4%)(2.8L) (interstitial fluid)
(16%)(11.2 L)
3. Water turnover
Intake per day
Water In food 700 ml
Oxidation of food 200ml
Drinking water 1600 ml
Total 2500 ml
Output per day
Urine 1500 ml
Skin 600ml
Lungs 300 ml
Feces 100ml
Total 2500 ml
17. Definition
• Dehydration occurs when you lose more fluid
than you take in.
• And your body doesn't have enough water
and other fluids to carry out its normal
functions.
– If you don't replenish lost fluids, you may suffer
serious consequences.
18. The average person loses about 2.5 liters of water
every day. So to stay properly hydrated you must
replenish this water in order to keep from being
dehydrated.
19. Daily Water Requirements
Drink 50-75% of your body weight in ounces.
Sedentary people: 50%;
Moderate: 62%
Active people: 75%
20. Causes of Dehydration
• Intense diarrhea, vomiting, fever or excessive
sweating.
• Inadequate intake of water during hot
weather or exercise also may cause
dehydration.
• Young children, older adults and people with
chronic illnesses are most at risk.
21. Signs/Symptom of Mild to Moderate
Dehydration
• Dry, sticky mouth
• Sleepiness or tiredness
• Thirst
• Decreased urine (dark color) output — fewer than six wet
diapers a day for infants and eight hours or more without
urination for older children and teens
• Few or no tears when crying
• Muscle weakness
• Headache
• Dizziness or lightheadedness
22. Dehydration can lead to any of the following
problems:
• Cramps
• Headaches
• Diarrhea
• Fever
• Vomiting
• Hallucinations
• Death
In fact, dehydration is the leading cause in deaths of
infants.
Dangers of Dehydration
23. Staging of dehydration
There are three types of dehydration
• Mild – Less than 5% weight loss
• Moderate – 5-10% weight loss
• Severe – 10-15% weight loss
Severe dehydration requires immediate
medical attention and can lead to death.
24. Detecting Dehydration
• Skin pinch test
– falls back instantly -
normal
– 2 - 4 sec - moderate
– 4 -6 sec - severe
• Capillary refill
– press finger on gums
above an upper tooth
• if it takes longer than 2
seconds for blood to
return - dehydration
25. Lab evaluation
• Blood analysis
– PCV and total plasma proteins
• rise indicates dehydration
– if PCV > 50% indicates hazardous fluid loss
Serum Na & K high
28. • It is a potentially fatal disturbance in brain
functions
• It results when the normal balance of
electrolytes in the body is pushed outside safe
limits by over-hydration
29. • Water, just like any other substance, can be
considered a poison when over-consumed in a
specific period of time.
• Water intoxication mostly occurs when water
is being consumed in a high quantity without
giving the body the proper nutrients it needs
to be healthy
30. • Excess of body water may also be a result of a
medical condition or improper treatment
31. Physiology
• fluid outside the cells has an excessively low
amount of solutes in comparison to that
inside the cells
• fluid shifts into the cells to balance its
concentration
32. • This causes the cells to swell
• In the brain, this swelling increases
intracranial pressure (ICP)
• symptoms of water intoxication: headache,
personality changes, changes in behavior,
confusion, irritability etc
33. • These are sometimes followed by difficulty
breathing during exertion, muscle weakness,
cramping, nausea, vomiting, thirst, dulled
ability to perceive and interpret sensory
information, bradycardia , pulse pressure ,
cerebral edema etc.
34. Risk factors
• Low body mass (infants)
• Endurance sports (marathon runners)
• Overexertion and heat stress
• Psychiatric conditions (psychogenic
polydipsia)
• Iatrogenic
35. Treatment
• Mild intoxication may remain asymptomatic
and require only fluid restriction.
• In more severe cases, treatment consists of:
Diuretics to increase urination, which are most
effective for excess blood volume.
Vasopressin receptor antagonists (prevent
water reabsorption in kidney tubules)
37. • Total body K in a 70 kg oerson = 40-59
mmol/kg (of which 1.5% - 2% is present in
ECF)
• Loss of K = kidneys, feces, sweat
• Serum K = 3.5-5 mmol/l
47. • Disorders of Na+ homeostasis can occur
because of excessive loss, gain, or retention
of Na+
• Also because of excessive loss, gain or
retention of water
48. • It is difficult to separate disorders of Na &
water balance because of their close
relationship in establishing normal osmolality
in all body water compartments
49. Hyponatremia
• Serum Na : less than 135 meq/l
• Serum Na <120 meq/L (nausea, weakness,
mental confusion)
• Serum Na between 90-105 meq/L (severe
mental impairement)
50. Causes :
1. Due to fluid retention : -
a. Edematous fluid retention : -
i. Increased water intake : eg, inappropriate IV
saline
ii. Decreased water excretion : eg, nephrotic
syndrome
51. b. non-edematous fluid retention : -
i. Increased water intake : eg, compulsive
water drinking
ii. Decreased water excretion : eg, SIADH, RF
52. 2. Due to sodium deficit : -
a. GI loss : eg, vomitting, diarrhoea
b. Urinary loss : eg, aldosterone deficiency,
drug-spironolactone
53. Clinical features
• Dry mucus membrane
• Hypotension
• Loss of conciousness
• Decreased skin turgor
• Sunken eyeball
• Tachycardia
• Increased pulse
55. Hypernatremia
• Serum Na : >150 mmol/l
• Hyperosmolar plasma
• Assessment of TBW status by physical
examination and measurement of urine Na &
osmolality are important steps in establishing
a diagnosis for hypernatremia.
56. Causes :
1. Normal sodium with decreased water :
i. Decreased water intake
ii. Renal water loss : eg, diabetes insipidus
2. Decreased Na with very much decreased
water :
i. Osmotic diuresis : eg, diabetes mellitus
ii. Excessive sweating or diarrhoea in children
57. 3. High Na with normal water :
i. Na administration
ii. Conn’s syndrome, cushing’s syndrome
58. Features
• Fluid loss – dehydration
• Salt overload – pulmonary edema
• Neurological symptoms (due to intraneuronal
loss of water to the ECF)
• Tremor, irritability, ataxia, confusion, coma
60. Disorders of Chloride
• Most abundant anion in ECF
• In the absence of acid-base disturbances, Cl-
concen in plasma generally follow those of Na+
• Helps in HCl formation
• Takes part in chloride shift process
• essential for calculating the anion gap and in
the differential diagnosis of acid-base
disorders
61. • Fluctuations in serum Cl- serves as signs of
disturbances in fluid & acid-base homeostasis
• CSF Cl- : 125 meq/L
• Urine Cl- : 5-8 gm/day
62. Hyperchloremia
• Increased plasma Cl- >107 meq/L
Causes :
Dehydration
Renal tubular acidosis
Acute renal failure
Metabolic acidosis associated with prolonged
diarrhoea & loss of bicarbonate
64. Hypochloremia
• Hypochloremia is frequently observed in
metabolic acidosis that are caused by
increased production or diminished excretion
of organic acid (DKA & renal failure)
• In such cases, total anion concen. represented
by Cl- is diminished because of increase in β-
hydroxybutyrate, acetoacetate, lactate &
phosphate
65. causes
Causes of hypochloremia parallel those causes
of hyponatremia
• Excessive vomitting
• Excessive sweating
• Addisson’s disease
• Persistent gastric acid secretion
