Fluid and Electrolyte Imbalance Lecture 2

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Sodium Imbalance • Normal value ( 135-145mEq/L)• Sodium is a primary determinant of serum

osmolarity. Increase in sodium lead to increase osmolarity

• Sodium also has a major role in water distribution. Sodium and water usually are lost and gained together

• Sodium is important in creation and transmission of nerve impulse and muscle contraction

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• Sodium deficit ( Hyponatremia): defined as sodium level below 135mEq/L

Can happened in 2 cases :• Loss of sodium from blood in a proportion that

is higher than loss of water• Significant increase in water with no change in

sodium content ( dilution hyponatremia)• Hyponatremia can happened in both

hypervolemia and hypovolemia

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Causes of hyponatremia

• Vomiting, sweating, diarrhea, fistula, use of diuretics if combined with loss sodium intake

• Deficiency of aldosterone• ( up normal) Increase anti diuretic

hormone( ADH) such as in syndrome of inappropriate antidiuritic hormone ( SIADH).

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Clinical manifestations of hyponatremia • With minor change Poor skin turgor, headache,

dry mucosa, orthostatic hypotension• With a level of less than 115mEq/L neurologic

changes such as alteration in mental status, increase intracranial pressure seizure and coma.

• Hyponatremia results in accumulation of water in brain tissue ( cerebral edema) due to osmotic gradient.

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Diagnostic findings in hyponatremia

• Decrease serum sodium ( less than 135mEq/L)

• Decrease urine sodium to less than 20mEq/L as the kidney try to conserve sodium

• Low urine specific gravity (1.002-1.004)

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Management of hyponatremia

• Sodium replacement : increase oral intake• Normal saline 0.9% or Ringer Lactate IV• Sodium should not be increased in a rate

higher than 12mEq/L• Water restriction less than 800ml/24hrs in

case of fluid excess such as (SIADH)

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Sodium excess (Hypernatremia )• High serum sodium more than 145mEq/L• Cause by increase is sodium in different

proportion than water• Can happened in both hypervolemia and

hypovolemia CausesDecrease fluid intake ( especially in unconscious

patient).Administration of hypertonic saline solutionDrowning in sea water

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Clinical manifestation of hypernatremia • Neurologic manifestation as a result of increase

plasma osmolarity and movement of water out of the cells.

• Restlessness, weakness, delusion hallucination • Thirst Assessment and diagnostic findings Increase sodium higher than 145mEq/L and

serum osmolarity higher than 300mOsm/kg

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Medical management of hypernatremia • Administer hypotonic saline solution such as

NS 0.45%• Sodium level is reduced in a rate no faster

than 0.5 to 1 mEq/L/ hr

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Potassium Imbalance • Normal value in serum is 3.5-5mEq/L• Potassium is a major intracellular electrolyte• Influence both cardiac and skeletal muscle

activity• Potassium is very sensitive to change in serum

level• Kidney is the primary regulator of serum

potassium with 80% excretion through kidney while the other 20% is excreted via bowle and sweat

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Potassium Deficit (Hypokalemia)

• Decrease in serum potassium less than 3.5mEq/L

• Causes include diuretics, Gastrointestinal loss as in vomiting and diarrhea, illeostomy.

• Increase aldosteron secretion• Diuretics ( lasix)• Increase insulin secretion as in diabetes I

insulin increase entry of insulin into skeletal muscle and hepatic mucles

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Clinical manifestations of hypokalemia • Fatigue, anorexia, nausea• Muscle weakness, paresthesia, decrease bowel

motility• Inability of kidney to excrete urine • Increase sensitivity to digitalis( digoxin)• Electrocardiogram (ECG) changes flat T wave,

inverted T wave, depressed ST segment elevated U wave

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Medical management of hypokalemia

• Potassium supplement: usually 40-80mEq/L• High potassium diet as most fruits, legume,

whole grain, milk, meat.• Potassium chloride is a routine supplement

and usually the concentration is 20mEq-40mEq/ for each liter

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Potassium Excess (Hyperkalemia)

• Potassium decrease less than 3.5mEq/LCauses• mainly is decrease renal excretion ( renal

failure).• Decrease aldosteron secretion.• Side effect of medications such as heparin,

ACE inhibitor (captopril), NSAID, potassium sparing diuretic such as spironalacton( aldacton)

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Clinical manifestations of hyperkalemia • The most common is cardiac when the level is

higher than 7mEq/L and early changes can be noted at a value 6mEq/L such as:

• Peaked narrow T wave• St segment depression• Shortened QT interval• PR interval prolonged followed by disappearance

of P wave.• Prolongation of QRS complex that entails cardiac

arrhythmia and cardiac arrest • Muscle weakness may be paralysis related to

depolarization block ( speech muscle and respiratory muscle 04/18/23 16

Medical management of hyperkalemia

• Restriction of potassium• Cation exchange resin ( Kayexalate): bind with

potassium in the intestine and removed through stool.

• Administration of calcium gluconate ( to protect the heart but has no effect on the potassium level)

• Administration of sodium bicarbonate• Administration of hypertonic dextrose solution

with insulin: insulin bind potassium and sugare and move it to the cells

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Calcium Imbalance • 99% of the total body calcium in the skeletal

system• Normal serum value for the total calcium is

8.6-10.2mg/dl ( 2.2-2.6mmol/L) .• The ionized calcium 4.5- 5.1mg/dl) ( the lap

give readings for both ionized and total)• Calcium is absorbed in the food in the

presence of gastric acidity and vitamin D• Excretion mainly via feces with the reminder

through urine 04/18/23 18

Calcium deficit ( Hypocalcemia)• Lower than 4.5- 5.1mg/dl for the ionized or

lower than 8.6mg/dl for the total • Causes include hypoparathyroidism ( decrease

parathormon cause less release of calcium from the bone)

• Inflammation of pancreas( pancreatitis)• Renal failure ( because of increase in

phosphate cause decrease in calcium)• Inadequate vitamin D consumption

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Clinical manifestations of hypocalcemia

• Increase neuronal excitability resulting in Tetany: increase both sensory and motor peripheral nerve discharge . Symptoms of tetany include general tingling in fingers and feet, face, and around mouth

• Trousseau’s sign• Chvostek’s sign• Mental changes then Seizure • ECG changes such as prolonged QT interval,

prolonged St SEGMENT

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• Diagnostic findings of hypocalcemia• Serum calcium level and serum albumin level

(because significant amount of calcium in blood is bonded to albumin)

• Medical management • Increase dietary intake( milk, green leafy

vegetables, canned salmon, sardines, and oyster

• IV supplement as calcium gluconate, or calcium chloride

• Vitamin D therapy ( increase absorption from the GIT

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Calcium Excess ( Hypercalcemia)• Increase total calcium higher than 10.2mg/dl or ionized

calcium higher than 5.1 mg/dl.

• Causes include malignancy and hyperparathyroidism ( increase parathormone)

• Clinical Manifestations • Increase calcium lead to suppress neuronal activity at

the neuromuscular junction which cause muscle weakness, incoordination, anorexia, and constipation.

• Increase urine output due to disturbed renal function • Cardiac standstill in sever case when calcium is higher

than 18mg/dl 04/18/23 22

Medical management of hypercalcemia• Administer high volume of NS0.9% to dilute

the serum and increase urine output• Phosphate may be given as it increase calcium

excretion• Lazix rarely given as it increase excretion • Also rarely Calcitonin may be given as it move

calcium from the blood to the bone.

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