Test 1 - Hypo/Hyper

What is hyponatremia?

Sodium deficiency

What causes hyponatremia?

• Losses from excessive sweating, vomiting, and diarrhea

• Use of certain diuretic drugs combined with low-salt diets

• Hormonal imbalances

  • Ex. insufficient aldosterone, adrenal insufficiency, excess ADH secretion

    • Syndrome of inappropriate antiduretic hormone secretion

• Early chronic renal failure

• Excessive water intake

What are the effects of hyponatremia?

• Impaired nerve conduction (low sodium) resulting in fluid imbalances between the compartments.

• Decreased osmotic pressure in the extracellular compartment may cause a fluid shift into cells

• Brain cells might swell

How does impaired nerve conduction manifest in patients with hyponatremia?

Fatigue, muscle cramps, and abdominal discomfort or cramps with nausea and vomiting

How does a fluid shift into cells manifest in patients with hyponatremia?

Hypovolemia and decreased blood pressure

How does brain swelling manifest in patients with hyponatremia?

Confusion, headache, weakness, or seizures

What is hypernatremia?

Excess sodium

What causes hypernatremia?

• Ingestion of large amounts of sodium without proportionate water intake

• Loss of water from the body is faster than loss of sodium

• Specific Causes:

  • Insufficient ADH, which results in a large volume of dilute urine (Diabetes insipidus)

  • Loss of thirst mechanism

  • Watery diarrhea

  • Prolonged periods of rapid respirations

What are the effects of hypernatremia?

• Fluid shifts out of cells owing to increased osmotic pressure of interstitial or extracellular fluid.

What are the manifestiations of a fluid shift out of cells due to hypernatremia?

• Weakness, agitation

• Firm subcutaneous tissues (Table 2.5)

• Increased thirst, with dry, rough mucous membranes

• Decreased urine output, because ADH is secreted

• Note: the manifestation can change depending on the cause of the problem. If the cause of hypernatremia is fluid loss caused by a lack of ADH, the urine output is high

Why is sodum (Na+) important?

Sodium (Na+) is the major extracellular cation and has major osmotic effects.

Why is potassium (K+) important?

Potassium (K+) is a major intracellular cation.

• Intracellular fluid osmotic provider. 

• Essential for nerve functioning and muscle contraction. 

• Sodium-Potassium: 

  • Gradient between the inside and outside of the cell is established and maintained by sodium-potassium pumps, which actively transport potassium into cells and sodium out.

What disorder is hypokalemia sometimes associated with?

Alcoholism

What causes hypokalemia?

• Excessive losses from the body because of diarrhea 

• Diuresis associated with certain diuretic drugs

  • Ex. Patients with heart disease who are being treated with certain diuretic drugs such as furosemide may have to increase their daily intake of potassium in food or take a potassium supplement, as hypokalemia may increase the toxicity of heart medications such as digitalis

• Presence of excessive aldosterone or glucorticoids in the body

  • Ex. Cushing’s syndrome, in which glucorticoids have some mineralcorticoid activity that promotes retention of sodium and excretion of potassium

• Decreased dietary intake, which may occur with alcoholism, eating disorders, or starvation

• Treatment of diabetic ketoacidosis with insulin

What are the effects of hypokalemia?

• Cardiac dysrhythmias are serious

  • Shows typical ECG pattern changes that indicate prolonged repolarization and eventually lead to cardiac arrest

• Hypokalemia interferes with neuromuscular function, and muscles become less responsive to stimuli

  • Shown by fatigue and muscle weakness commencing in the legs

• Paresthesias (abnormal touch sensations) develop

  • “Pins and needles”

• Decreased digestive tract motility causes decreased appetite (anorexia) and nausea

• In people with severe potassium deficits, the respiratory muscles become weak, leading to shallow respirations

• In severe cases, renal function is impaired, leading to failure to concentrate the urine, and increased urine output (polyuria) results

What type of organ failure can cause hyperkalemia?

Renal failure

What is hyperkalemia?

Excess potassium

What causes hyperkalemia?

• Renal failure

• Deficit of aldosterone

• Use of  “potassium-sparing” diuretic drugs

  • Prevent potassium from being excreted in adequate amounts

• Leakage of intracellular potassium into extracellular fluids in patients with extensive tissue damage

  • Ex. traumatic crush injuries or burns

• Displacement of potassium from cells by prolonged or severe acidosis (Fig. 2.7)

What are the effects of hyperkalemia?

• The ECG shows typical cardiac dysrhythmias (Fig. 2.8) 

  • Progresses into cardiac arrest

• Muscle weakness is common

  • Progresses to paralysis as hyperkalemia advances and impairs neuromuscular activity (Table 2.6)

• Fatigue, nausea, and paresthesia (tingling sensation)  are also common

Explain Fig. 2.7 [insert image] explaining the displacement of K+ from inside cells by H+ during severe, prolonged acidosis.

• Acidosis: High concentration of H+ ions in the blood lead to a low pH/high acidity. 

• Acidosis leads to H+ moving out of the blood and into the interstitial fluid.

• H+ are then draw into the cell and displace K+ into the interstitial fluid. 

  • Mechanism to buffer excess H+ ions and to balance shift in ions.

• K+ are drawn into the blood, creating a high concentration of K+.

• High concentration of K+ in blood leads to hyperkalemia.

How can hyper- and hypokalemia affect the heart?

They can both result in cardiac dysrhythmias and cardiac arrest.

• Hypokalemia and hyperkalemia both have powerful electrophysiological effects that promote cardiac arrhythmias. 

  • Hypokalemia reduces repolarization reserve by directly inhibiting K+ channel conductances and indirectly by suppressing Na+-K+ ATPase.

  • Hyperkalemia enhances repolarization reserve by increasing K+ channel conductance, shortening APD, and inducing postrepolarization refractoriness, manifested electrocardiographically by peaked T waves.

What is hypoalcemia?

How is hypoalcemia related to renal failure?

Hypoalcemia may result from renal failure due to phosphate retention (phosphates and calcium can switch with one another)

• Calcium and phosphate ions in the extracellular fluid have a reciprocal relationship. 

  • If calcium levels are high, phosphate is low. The product of calcium and phosphate concentrations should be a constant value. 

  • If levels of calcium and phosphate ions rise, crystals of calcium phosphate precipitate in soft tissue. 

  • Alkalosis can decrease the number of free calcium ions, causing hypocalcemia. 

What are the two primary causes of hypocalcemia in chronic renal failure?

• Increased serum phosphorus

• Decreased renal production of vitamin D.

  • Vitamin D promotes calcium movement in the GI and bone.

What are the causes of hypocalcemia?

• Hypoparathyroidism (decreased parathyroid hormone)

  • Results in decreased intestinal calcium absorption

• Malabsorption syndrome

  • Results in decreased intestinal absorption of vitamin D or calcium

• Defiecent serum albumin

• Increased serum pH – resulting in alkalosis

  • In renal failure, hypocalcemia results in the retention of phosphate ions, which causes a loss of calcium

  • Also, vitamin D is not activated, thereby decreasing the intestinal absorption of calcium.

What are the effects of hypoalcemia?

• Increase in the permeability and excitability nerve membranes lead to spontaneous stimulation of skeletal muscle.

  • Muscle twitching, carpopedal spasm (atypical contraction of fingers), and hyperactive reflexes

  • The Chvostek sign, spasm of the lip or face when face is tapped in from of the ear.

  • The Trousseau sign, carpopedal spasm when blood pressure cuff blocks circulation to the hand, both indicate low serum calcium and tetany (skeletal muscle spasms causing prolonged contractions and/or cramps). 

  • Severe calcium deficiency may cause laryngospasm (obstructsthe  airway).

  • Parethesias are common, as are abdominal cramps. 

• Heart contractions become weak, owing to insufficient calcium for muscle action, conduction is delayed, arrhythmias develop, and blood pressure drops.

What are the signs of hypoalcemia?

• Tetany – involuntary skeletal muscle spasm, carpopedal spasm, laryngospasm

• Tingling fingers

• Mental confusion, irritability

• Arrythmias, weak heart contractions

What is hypercalcemia?

Excess calcium

What are the causes of hypercalcemia?

• Neoplasms can cause an uncontrolled release of calcium ions from the bones

• Hyperparathyroidism

• Immobility

• Increased intake of calcium

  • Excessive vitamin D

  • Excess dietary calcium

• Milk-alkali syndrome

How can neoplasms cause hyperalcemia?

• Malignant bone tumors may destroy the bone

• Some tumors secrete PTH (parathyroid hormone), a key regulator of blood calcium levels, in excess

How can hyperparathyroidism cause hypercalcemia?

It increases PTH, increasing calcium absorption.

How can immobility cause hypercalcemia?

It may decrease stress on the bone, leading to demineralization.

What are two causes of increased calcium intake, leading to hypercalcemia?

• Excessive vitamin D

• Excess dietary calcium

What is milk-alkali syndrome? How does it cause hypercalcemia?

A condition associated with increased milk and antacid intake, which may also elevate serum calcium levels.

What are the effects of hypercalcemia?

• Depressed neuro-muscular activity

• High calcium interferes with the function of ADH in the kidneys

• Cardiac contractions increase in strength and dysrhythmias may develop

• Effects on bone varying with cause

• May contribute to the formation of kidney stones in the urinary system

How does depressed neuro-muscular activity due to hypercalcemia manifest?

• Muscle weakness

• Loss of muscle tone

• Lethargy

• Stupor, often with personality changes, anorexia, and nausea

  • double check this last one

How does the interaction between calcium and ADH in the kidneys due to hypercalcemia manifest?

• Results in less absorption of water and in polyuria.

• If hypercalcemia is severe

  • blood volume drops, renal function decreases, nitrogen wastes accumulate, and cardiac arrest may ensue. 

How does hypercalcemia affect a patient’s bones?

• If excess PTH, bone density will decrease and spontaneous fractures may occur, particularly in weight-bearing areas

• If intake of calcium is high, PTH levels will be low, and more calcium will be stored in the bone, maintaining bone strength

What are the signs of Hypercalcemia?

• Apathy, lethargy

• Anorexia, nausea, constipation

• Polyuria, thirst

• Kidney stones

• Arrhythmias, prolonged strong cardiac contractions, increased blood pressure

What is hypomagnesmia?

Magnesium deficiency

What disorder can cause hypomagnesmia, and how?

Alcoholism. It is assocaited with malabsorption or malnutrition, which can cause hypomangesmia.

What are the causes of hypomagnesmia?

• Use of diuretics

• Diabetic ketoacidosis

• Hyperparathyroidism

• Hyperaldosteronism 

What are the effects of hypomagnesmia?

• Neuromuscular hyperirritability

• Tremors or chorea (involuntary repetitive movements)

• Insomnia

• Personality changes

• Increased heart rate with arrhythmias

What is hypermagnesmia?

Excess magnesium

What type of organ failure can cause hypermagnesmia?

Renal failure

What are the causes of hypermagnesmia?

• Usually occurs with renal failure

• Addison’s disease

• Hypothyroidism

• Excessive dietary consumption

• Magnesium-containing medications

What are the effects of hypermagnesmia?

• Depressed neuromuscular function

• Decreased reflexes

• Lethargy

• Cardiac arrhythmias

What is hyperphosphatemia?

Excess phosphate

What type of organ failure is hyperphosphatemia associated with?

Renal failure

What causes hyperphosphatemia?

• Often results from renal failure

  • Dialysis patients often take phosphate binders with meals to control their serum phosphate levels

• Tissue damage or cancer chemotherapy may cause the release of intracellular phosphate

What are the effects of hyperphosphatemia?

• Manifestations of hyperphosphatemia are the same as hypocalcemia

  • Tetany – involuntary skeletal muscle spasm, carpopedal spasm, laryngospasm

  • Tingling fingers

  • Mental confusion, irritability

  • Arrhythmias, weak heart contractions

What is hypochoremia?

Chlorine deficiency

What are the causes of hypochloremia?

• Associated with alkalosis in the early stages of vomiting when hydrochloric acid is lost from the stomach

• Excessive perspiration associated with fever or strenuous labor on a hot day can lead to loss of sodium chloride

  • Results in hyponatremia and hypochloremia, and ultimately dehydration

What two physical processes can cause hypochloremia?

Vomiting and excessive persipiration

What are the effects of hypochloremia?

• Nausea

• Vomiting

• Diarrhea

• Muscle twitching

• Confusion, sleepiness