Chapter 7 Fluid and Electrolyte Imbalances

normal serum albumin levels

3.1-4.3 g/dL Changes in this albumin level alter oncotic pressure

Transudate

A serous filtrate of blood

Hyperkalemia

A blood K+ level greater than 5.2 mEq/dL. Normal kidney function is important in the regulation of potassium. Any decrease in renal perfusion, such as decreased cardiac output, will diminish the kidney's ability to excrete K+, thus increasing the amount of potassium in the body.

ATPase pump

Membrane pumps that use the hydrolysis of ATP to translocate ions against their electrochemical gradients. Sodium and potassium require this pump to maintain Na+ as the extracellular ion and K+ as the intracellular ion.

Dehydration

A state of diminished water volume in the body. A deficit in intracellular fluid, which causes body cells to shrink. It causes hypovolemia a diminished level of circulating blood volume that increased the osmolarity of the blood. There is also a decreased amount of water in the extracellular fluid. Causes include reduced fluid intake, excessive fluid loss caused by illness, lack of sufficient ADH production or lack of renal stimulation by ADH can also lead to excessive fluid loss and dehydration, as can certain gastrointestinal disorders such as prolonged diarrhea.

symptoms of hypokalemia

Anorexia, nausea, vomiting, sluggish bowel, cardiac arrhythmias, postural hypotension, muscle fatigue, leg cramps, and weakness. Respiratory muscles can be weakened with severe state of this condition. There can be decreased or absent deep tendon reflexes on physical examination.

Conditions that cause dehydration and increase water requirements

Bleeding, breastfeeding, burns, fever, GI fluid loss, hypotension, nephrolithiasis, polyuria, surgical drains, sweating, tachypnea

Baroreceptors

Blood vessel receptors that sense a decreased blood pressure in dehydration. This, in turn, stimulates the sympathetic nervous system, which vasoconstricts arterial vessels and increases heart rate to compensate.

Sodium

Main extracellular electrolyte Primary determinant of the ECF's osmolarity and volume. It must be constantly pumped out of the cell into the bloodstream.

Potassium

Main intracellular electrolyte

fluid homeostasis

maintaining fluid (ie water) levels in the body at a near constant level In terms of fluid volume, both fluid intake and output must be regulated to prevent fluid volume overload, also known as edema, and fluid volume deficit, also known as dehydration. However, in addition to fluid volume status, the relative composition of body fluids, including electrolyte and acid or base concentrations, needs to be consistent. The kidney, RAAS, Osmoreceptors, thirst sensation, antidiuretic hormone, and natriuretic peptides work together to maintain fluid homeostasis in the body.

Normal plasma osmolality range

282-295 milliosmoles per kilogram of water

High osmolality

Indicates greater amount of solutes

Treatment of hypophosphatemia

Replacement therapy

renin-angiotensin-aldosterone system

-decreased blood pressure causes the juxtaglomerular cells of kidneys to secrete renin which converts angiotensinogen (inactive- a large protein produced by the liver) to angiotensin I (active), in the lungs, angiotensin 1 is then converted into angiotensin II (a powerful vasoconstrictor) by angiotensin-converting enzyme (ACE) -Angiotensin II stimulates the adrenal cortex to secrete aldosterone - aldosterone, which is a mineralocorticoid, that increases sodium and water reabsorption into the bloodstream at the distal tubule of the nephrons, therefore increasing blood pressure -once blood pressure is restored, aldosterone secretion is reduced and there is a decreased drive to stimulate renin release, therefore shutting off RAAS system

Hypercalcemia

A calcium level greater than 10 mg/dL. Will occur when the amount of calcium entering the ECF exceeds calcium excretion by the kidneys. The two common causes are hyperparathyroidism and cancer. In hyperparathyroidism, the PTH is overproduced, and the hormone pulls excessive amounts of calcium out of the bones and into the bloodstream. Cancer related is caused by malignant cells invading the bone, causing bone destruction. Cancer also releases a parathyroid-like hormone, causing an increase in serum calcium levels. S/S involve decreased neuromuscular excitability. Muscle flaccidity, proximal muscle weakness of lower extremities, bone tenderness, decreased neuromuscular activity of the bowel causing constipation. Other nonspecific effects include dulled consciousness, depression, anorexia, nausea, vomiting and ulcers. Hyperreflexia and tonguefasciculations may also occur.

Hypermagnesemia

A magnesium blood level of greater than 2.5 mEq/L. Magnesium is often used to treat cardiac disorders and pregnancy-related eclampsia, and levels must be carefully monitored. High Mg++ inhibits acetylcholine release and can cause diminished neuromuscular function, demonstrated by hyporeflexia and muscle weakness. Magnesium also blocks calcium channels and can cause CV effects such as hypotension and arrhythmias. Severely high Mg++ levels (greater than 10 mEq/L) can cause cardiac arrest.

Tolvaptan

A medication indicated for the treatment of clinically significant hypervolemic hyponatremia, which is indicated by a serum sodium of 125 mEq/L or less marked hyponatremia that is symptomatic and has resisted correction with fluid restriction.

Hypernatremia

A sodium level greater than 145 mEq/L. It can occur with an excess of or decrease in body water. Most commonly, It is caused by water loss, although It can be caused by salt loading. Cells become dehydrated. The high osmotic load of the increased sodium acts to extract water from the cells. Dehydrated cells shrink from water extraction. Cells immediately respond to combat this shrinkage and osmotic force by transporting electrolytes across the cell membrane, this altering rest potentials if electrically active membranes. After an hour, intracellular organic solutes are generated in an effort to restore cell volume and to avoid structural damage. This protective mechanism is important to remember when treating a patient with this condition. Cerebral edema ensues if water replacement proceeds at a rate that does not allow for excretion or metabolism of accumulated solutes.

Treatment of hypokalemia

Accomplished by replacement of potassium with foods such as orange juice, bananas, dried fruits, meats, and oral or parenteral K+ preparations. Potassium can also be prescribed intravenously; commonly 20 mEq of potassium chloride (KCl) per liter of intravenous solution is administered to NPO patients, not to exceed a total of 60 mEq/day.

Causes of hypocalcemia

Alcohol abuse, drugs (loop diuretics, anticonvulsants, calcitonin, gentamycin, phosphates), hyperphosphatemia, hypoalbuminemia, hypomagnesemia, hypoparathyroidism, inadequate dietary intake or inadequate vitamin D, malabsorption, pancreatitis, sepsis.

causes of hypermagnesemia

Alcohol withdrawal, antacid abuse, burns, decreased intestinal absorption of PO4-, diabetic ketoacidosis, hyperalimentation (nutrient-rich intravenous solution), hypercalcemia, hyperparathyroidism, increased renal loss of PO4-, lack of vitamin D, respiratory alkalosis.

Causes of hypokalemia

Alkalosis, diuretic therapy, elevated glucocorticoids, excessive gastrointestinal/renal/skin losses, hyperaldosteronism, inadequate intake, laxative abuse, nasogastric suction, redistribution of potassium (K+) between the intracellular and extracellular spaces

causes of hypernatremia

Certain medications such as osmotic diuretics, sodium, bicarbonate, and sodium chloride, Cushing's syndrome, diabetes insipidus (lack of antidiuretic hormone), diarrhea, excess sodium administration, excessive adrenocortical secretion, hypercalcemia, impaired thirst, increased aldosterone, potassium depletion, profuse diaphoresis, tube feedings with lack of adequate water administration, uncontrolled diabetes mellitus, water deprivation.

Hypocalcemia

Consists of a blood calcium level of less than 8.7 g/dL in adults. Acute version of this condition is manifested by neuromuscular excitability, which is demonstrated in individuals as a subjective experience of paresthesias around the mouth, hands, and feet; muscle spasms of the face, hands, and feet; laryngeal spasm; seizures; and death. Cardiovascular effects include hypotension, arrhythmias (particularly heart block and ventricular fibrillation), and failure to respond to cardioactive drugs. Chronic version of this condition causes bone pain and fragility, dry skin and hair, cataracts, depression, and dementia. Chvostek's sign and Trosseau's sign are examples of neuromuscular irritability causes by chronically low calcium levels.

Hypophosphatemia

Consists of a blood level of phosphate lower than 2.5 mg/dL. Three main causes: decreased intestinal absorption of phosphorus, increased excretion if phosphorus by the kidneys, and an intracellular shift of phosphate. Low phosphate causes red blood cell, white blood cell, and platelet dysfunction, as well as neural dysfunction and disturbed musculoskeletal function. Lack of sufficient phosphate can cause tremors, paresthesias, hyporeflexia, anorexia, dysphagia, muscle weakness, joint stiffness, bone pain, and osteomalacia.

Asses fluid volume status

Daily weight I&O

Causes of hypercalcemia

Decreased elimination of calcium, drugs (diuretics, chemotherapy, androgens, estrogen, lithium, theophylline), excess vitamin D, hyperparathyroidism, increased bone resorption of calcium, increased intestinal absorption of calcium, malignancy such as bone/multiple myeloma/blood/breast/lung cancer, prolonged immobility, renal insufficiency.

Treatment of hyperphosphatemia

Directed at correcting the cause of the disorder. Calcium-based phosphate binders, such as sevelamer and lanthanum carbonate, inhibits GI absorption of phosphate. Dialysis can also reduce this

Starling's law of capillary forces

Explains the movement of fluid that occurs at every capillary bed in the body. There are two major opposing forces at every capillary membrane: 1. Hydrostatic pressure 2. Osmotic pressure (includes oncotic pressure) Within every capillary, the blood contains electrolytes and proteins that exert osmotic pressure. The fluid within the capillary exerts hydrostatic pressure. These pressure forces oppose each other and attempt to balance each other out at every capillary membrane, thereby creating a state of homeostasis

antidiuretic hormone (ADH)

Hormone produced by the neurosecretory cells in the hypothalamus that, once synthesized It travels by an axonal transport mechanism to the posterior pituitary gland. When the bloodstream lacks sufficient water, plasma osmolarity is increased and the osmoreceptors shrink. This stimulates "these" neurons to depolarize, releasing this hormone from the posterior pituitary. After release into the bloodstream, it stimulates water reabsorption from kidney (nephron) tubule fluid at the collecting duct into the blood and vasoconstriction of arterioles. When high plasma osmolarity stimulates osmoreceptors in the hypothalamus, this also stimulates the hypothalamic thirst center of the brain as well as promoting the release of this hormone from the posterior pituitary. When there is enough water in the bloodstream, plasma osmolarity decreases, and ADH secretion is inhibited.

Clinical manifestations of hypernatremia

If It causes water retention, then the picture is one of an edematous state: weight gain and hypertension. With severe edematous states, there may also be mental changes and pulmonary edema causing dyspnea. If It is that of sodium retention and water loss, the patient will appear to be dehydrated and demonstrate thirst, irritability, tachycardia, flushed skin, dry mucous membranes, and oliguria.

Causes of renal hypovolemic hyponatremia

Include adrenal insufficiency, osmotic diuresis, diuretic use, and salt-losing nephritis.

Causes of nonrenal hypovolemic hyponatremia

Include diarrhea, vomiting, excessive sweating, cystic fibrosis, gastric lavage, fistulas, burns, and wounds.

Low osmolality

Indicates there are fewer amounts of solutes in solution

Treatment of hypermagnesemia

Intravenous calcium or dialysis can be used for treatment.

Treatment of hypercalcemia

Involves enhancement of urinary excretion of calcium and inhibition of bone breakdown. Increased fluids and loop diuretics enhance calcium secretion. Biphoshonates, such as alendronate, and calcitonin are used to inhibit bone breakdown. Dialysis can be used in patients with kidney or heart failure.

Osmolality

Is a measurement of the concentration of solutes per kg of solvent It is based on 1 mole (or gram molecular weight equivalent) of a substance dissolved in 1 kilogram of water In clinical practice, this can be used to evaluate the body's hydration status based on the concentration of fluid and particles in solution

Calcium

Is an important element in the body because of its role in the formation and function of bones and teeth, normal clotting, and regulation of neuromuscular irritability. It is stored in the bone, bound to plasma proteins, and bound with organic ions such as citrate. A small amount of this element also remains free, this free, or ionized, element interacts in normal physiologic functions. The ionized form participated in cellular activities such as enzymatic reactions; neuron excitability; muscle contraction; release of hormones, neurotransmitters, and other chemical messengers; blood vessel contractility; cardiac contractility and automaticity; and blood clotting. Found in both ECF and ICF. Highly protein bound, interpretation of calcium levels is based on serum albumin levels. About half of this element is bound to albumin.

Treatment of hyperkalemia

Is dependent on the cause. If condition is severe (greater than 7.0 mEq/L), rapid treatment is needed to move K+ from ECF to ICF. Continuous ECG monitoring is necessary. An infusion of 50% dextrose, 10 units of regular insulin, and 75 mEq of sodium bicarbonate can be administered. If K+ levels continue to be elevated and the patient has normal renal function, a diuretic such as Lasix can be administered. Calcium chloride or calcium gluconate (Kalcinate) can also be administered. Another options for treatment is to give sodium polystyrene sulfonate (Kayexalate), which acts at the bowel to capture potassium and excrete it via feces. Alternatively, if the patient is in renal failure, dialysis can reduce K+.

C-type natriuretic peptide (CNP)

Is produced by endothelial cells of the arteries and ventricular cells of the heart in response to excess ECF volume

Brain Natriuretic Peptide (BNP)

Is produced in the heart's ventricles and, to a lesser extent, in the brain. It is excreted in response to fluid volume overload stretching the heart's ventricles- the more the ventricle is stretched by blood volume, the more this peptide is secreted.

Potassium

Is the main intracellular cation; It assists in the maintenance of neuromuscular excitability and acid-base balance.

Magnesium

Largely stored in bone and, like calcium, is protein bound within the bloodstream. It is the most abundant cation in the ICF. It is required for many cellular metabolic processes, such as functioning of nerve conduction, replication and transcription of DNA, translation of RNA, intracellular enzyme reactions, and all processes that require ATP. CV system requires this for vasodilation and normal functioning. Also affects sodium and potassium levels both inside and outside the cell membrane. Can also compete with and exert effects on calcium-mediated processes, because of its effect on the parathyroid gland. Ingested from meats, seafood, green vegetables, and some sources of ground water. Absorbed from the intestine, reabsorbed in the loop of Henle, and the excreted by the kidney. It is inhibited by high plasma calcium levels and high PTH levels. Also assists in the release of PTH. Interdependent relationship with potassium, increase and decrease together.

Hypomagnesemia

Magnesium Blood level of less than 1.5 mEq/L. In this disorder, Mg ++ ions are released from bone in exchange for increased uptake of calcium. Usually occurs in conjunction with hypocalcemia and hypokalemia. S/S are similar to those of low Ca and K levels. These include neuromuscular manifestations such as tetany, Chvostek's sign, Trosseau's sign, and cardiac arrhythmias.

calcium and phosphorus

Major mineral contents of bone.

Serum osmolality calculation

Milliosmoles of solute/ kg of water= 2 x serum sodium + serum glucose/ 18 + BUN / 2.4

Hypoalbuminemia

Occurs in severe protein starvation. There is an imbalance between oncotic pressure and hydrostatic pressure at every capillary interface. Hydrostatic pressure overwhelms oncotic pressure and It pushes water out of the capillary into the ISF and ICF. Edema occurs throughout the body at every capillary-cell interface, and this is often most apparent in the peritoneal cavity as a swollen abdomen.

edema

Occurs when there is an excess of fluid in the ISF and ICF compartments. Can occur because of elevated hydrostatic pressure created by excess water in the bloodstream or diminished osmotic force created by a low amount of solutes in the bloodstream. Can also occur because of inflammation, which causes increased capillary permeability; the capillary pores enlarge to allow fluid and cells out of the bloodstream to reach the site of injury. The fluid that movies into the ISF and ICF causes "this." Can also occur because of a low amount of solute in the bloodstream.

cellular dehydration

Occurs with loss of ICF, causing the cells to shrink. The ECF gains fluid, which is excreted via the kidney; this leads to further dehydration. This situation continues until water is replenished. Can also occur because of hypernatremia.

dependent edema

Often forms in the lower extremities. A weakened venous valve system, lack of muscle contractions, and gravitational forces can allow venous blood to collect in the lower extremities. When an individual stands or sits in one position for an extended period of time, venous blood can pool in the lower extremities. Increased hydrostatic pressure in the veins allows fluid to flow out of the capillary into interstitial tissues. Fluid accumulates in the ankles and feet. Brisk venous circulation back to the heart and vigorous muscle activity need to be maintained in the lower extremities in order to help this.

Digitalis toxicity

Often occurs when the patient is in the state of hypokalemia. Digitalis is a drug used in heart failure. Heart failure often causes a loss of potassium because of the cycling of the RAAS when the heart is weakened. When digitalis is administered to a patient, potassium and digitalis compete for binding sites in the heart. In hypokalemia, there are open binding sites for potassium in the heart and digitalis binds to these sites. When a high number of binding sites become occupied by digitalis, there is an increased potential for "this."

isotonic solution

Same tonicity as blood; when infused as an intravenous solution, It does not cause fluid shifts or alter body cell size. It has a concentration of particles and fluid that is similar to bloody and body fluids. Standard solution 0.9% NaCl aka normal saline: used frequently as a bloodstream volume expander. Often It is used to keep an open connection to the intravenous route for medication administration or a blood transfusion.

Hyponatremia

Serum sodium less than 135 mEq/L. Most commonly occurs when water excretion is impaired and it is diluted within a large volume of water in the bloodstream. Can occur in the presence of hypervolemia because it is diluted within an excess of water

Hydrostatic Pressure

The "pushing" force exerted by water in the bloodstream. The heart is the main source of pushing pressure with is pulsatile pumping action, It exerts an outward force that pushes water through thd capillary membrane pores into the ISF and ICF. Osmotic pressure opposes this pressure at all capillary membranes

Sodium

The main determinant of osmolarity, is a positive ion, also called a cation; It is found mostly in the ECF and assists in the maintenance of fluid balance and osmotic pressure.

Osmolarity

The number of osmoles of solute per litre of solution; It is dependent on the number of particles suspended in a solution.

Natriuretic peptides

There are three major peptides that promote natriuresis: atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). Secreted in response to excess ECF/blood volume.

S/s of dehydration caused by hypovolemic hyponatremia

Thirst, dry mouth, orthostatic hypotension, tachycardia, azotemia (high blood urea nitrogen concentration), and oliguria.

Hypertonic solution

This contains more particles and less water than blood and body fluids. When It is infused into the bloodstream, this adds solutes to the bloodstream and causes fluids to shift from ICF to ECF, causing body cells to shrink. A commonly used solution of this nature is Mannitol. It can be used to diminish cell swelling, particularly in cerebral edema. Another solution is 3.0% NaCl.

sodium-potassium pump

a carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell Constantly at work to try to retain K+ in the intracellular compartment and move Na+ to the extracellular environment.

action potential

a neural impulse; a brief electrical charge that travels down an axon Impulses generated along neuronal axons, are created by changes in sodium and potassium ions in ICF and ECF. During "this," sodium ion channels open in the plasma membrane, sodium ion channels open in the plasma membrane, allowing the entry of sodium ions into the cell. This is followed by the opening of potassium ion channels that permit the exit of potassium ions from the cell. The inward flow of sodium ions increases the concentration of positively charged cations in the cell and causes depolarization, where the potential of the cell is higher than the cell's resting potential. The sodium channels close at the peak of the action potential, whereas potassium continues to leave the cell. The efflux of potassium ions decreases the membrane potential in the repolarization phase.

causes of hypomagnesemia

alcoholism, citrated blood, drugs such ass diuretics/aminoglycosides/antibiotics/amphotericin/cyclosporine, liver failure, malabsorption, malnutrition, renal failure, Prolonged diarrhea, laxative abuse, increased renal excretion of magnesium, sepsis, burns, and serious wounds requiring debridement

Natriuresis

excretion of a large amount of sodium and water in the urine by the kidneys in response to excess ECF volume. although this is normal, this term usually applies to greater than normal sodium excretion It is a process of natural diuretics initiated by the body.

oncotic pressure

force exerted specifically by albumin in the bloodstream Albumin is the main colloidal protein in the bloodstream and is essential for maintaining this type of pressure in the vascular system Albumin attracts water and helps keep It inside the blood vessel

Atrial natriuretic peptide (ANP)

hormone secreted from atrial cells of the heart in response to excess ECF volume that causes atrial stretching and an increase in circulating blood volume. ANP has been identified as a diuretic that causes sodium loss and inhibits the thirst mechanism

Phosphate

intracellular negative ion, aka anion

pitting edema

occurs when pressure is applied to a small area and an indentation persists for some time after the release of the pressure Depending on the severity, an individual can have +1, +2, or +3 grading

Osmotic Pressure

"Pulling" force that pulls water into the bloodstream from the ICF and ISF. The pressure exerted by the solutes in a solution In the bloodstream, this is exerted by electrolytes (mainly sodium ions and plasma proteins). Opposes hydrostatic pressure

Hyperphosphatemia

A PO4- level of 4.5 mg/dL or greater in the blood. The most common cause is kidney failure, where the kidneys are unable to excrete phosphorus. Usually accompanied by hypocalcemia, and many of its symptoms are related to low calcium levels.

parathyroid hormone

Acts on bond to mobilize calcium and raise blood levels. Controls calcium levels. When the plasma calcium level is low, this is stimulated; when the plasma calcium level is high, this is inhibited.

Causes of hyponatremia

Adrenal insufficiency, burns, cirrhosis, CHF, diaphoresis with more salt lost then water, diarrhea, diuretic therapy, excess hypotonic fluid administration (called dilutional hyponatremia), hyperglycemia, hypoaldosteronism, laxatives, nasogastric suction, psychogenic polydipsia, renal disease, syndrome of inappropriate antidiuretic hormone (SIADH- which causes excess reabsorption of water into the bloodstream at the nephron).

Phosphorus

An essential component of bone, red blood cells, enzymatic processes, formation of adenosine triphosohate (ATP), acid-base balance, and cellular building blocks. Found in bone and circulated in the blood as phosphate (PO4-).

S/S of fluid volume excess

Ascites Crackles in lungs Dyspnea caused by pulmonary fluid accumulation Edema, either ankle or sacral Weight gain (2 lbs= 1 liter of fluid)

Hypoalbuminemia

Causes an imbalance in oncotic pressure versus hydrostatic pressure forces. With reduced albumin, the oncotic pressure is low and force exerted by hydrostatic pressure overwhelms the oncotic pressure. This causes water in the bloodstream to push outward from the capillary pores toward the ISF and ICF

Kwashiorkor

Condition in which persons are starving. Without sufficient nutritional protein, blood albumin levels become extremely low and, consequently, oncotic pressure is diminished causing third spacing. Most apparent in the peritoneal cavity as a swollen abdomen.

Exudate

Contains material such as blood, lymph, proteins, pathogens, and inflammatory cells.

s/s of fluid volume deficit

Dark urine with high specific gravity Depressed fontanelles (infant) Dry mucous membranes Low urine output Orthostatic hypotension Poor skin turgor Thirst Weight loss

treatment of hypernatremia

Depends on the underlying cause. Replacement fluids can be given orally or parenterally if It is caused by fluid depletion. Oral glucose-electrolyte replacement solutions are available for infants and children. If excess water is present, diuretic therapy may be necessary.

Hypotonic solution

Fewer particles and more water than blood and body fluids. It adds water the the bloodstream and causes a fluid shift from ECF to ICF to deliver water to the body as in dehydration treatment. A standard solution of this nature is 0.45% NaCl, and is also referred to as half normal saline Causes cells to swell Lower tonicity

effusion

Fluid that accumulates in body cavities that are normal free of fluids such as the pericardial sac, peritoneal cavity, and pleural space. Can be a transudate or exudate

When a membrane such as a cell membrane separates two solutions with different osmotic pressures, fluid will move from the solution that has the ______ osmotic Pressure into the solution that has the ______ osmotic pressure.

Lower, higher This is why a high osmotic pressure in the bloodstream favors fluid movement from the ICF and ISF into the bloodstream. Conversely, when the osmotic pressure is reduced, fluid moves out of the bloodstream and into interstitial and intracellular spaces

Symptoms of hyperkalemia

Numbness or tingling of the extremities Muscle cramping Diarrhea Apathy Mental confusion

orthostatic hypotension

Occurs in dehydration, is a systolic blood pressure decrease of at least 20 mm Hg or a diastolic blood pressure decrease of at least 10 mm Hg within 3 minutes when going from a lying to a standing position.

Fluid volume overload

Occurs when the bloodstream has an excessive amount of water. One of the most common causes is heart failure. Can also been seen in certain types of cancer that secrete ADH and cause SIADH Other ADH-related causes are cirrhosis of the liver, polycystic kidney disease, and some forms of hypertension.

Magnesium

Plays an important role in enzymatic systems within the body

Calcium

Plays an important role in neuromuscular irritability, blood clotting, and bone structure

Hypokalemia

Refers to a plasma concentration of potassium below 3.5 mEq/L.

Tonicity

Refers to the amount of solutes in solution compared with the bloodstream Used to describe the various intravenous solutions used in the clinical setting

Treatment of hypomagnesemia

Replacement therapy commonly with magnesium sulfate.

Treatment of hypocalcemia

Requires calcium replacement. Oral calcium supplements with vitamin D are often used, as Vitamin D is needed for calcium absorption from the intestine.

Osmoreceptors

Respond to the blood's high osmotic content and stimulate the thirst center in the hypothalamus. Also stimulate ADH secretion from the posterior pituitary gland, ADH works at the nephron to increase water reabsorption into the bloodstream.

Bicarbonate

Responsible for acid-base balance

hypovolemic hyponatremia

When dehydration occurs because the body has lost sodium and fluid together; it's cause is either renal or nonrenal.

Hyperkalemia ECG

Wide QRS complexes and tall, peaked T waves. As the potassium level rises, the ECG will show bradycardia, irregular pulse rate, and, ultimately, cardiac arrest.

dilutional hyponatremia

a serum sodium that is low not because of an absolute lack of sodium but because of an excess of water in the bloodstream

major solutes in the body

albumin, sodium (Na+), potassium (K+), phosphate (Po4-), magnesium (Mg++), calcium (Ca++), bicarbonate (HCO3-), and glucose

Hypokalemia ECG

prolonged PR interval, flattened T wave, and prominent U wave

Osmoreceptors

respond to changes in osmolarity of the blood and blood fluid volume (water homeostasis) High plasma osmolarity stimulates these in the hypothalamus, which then stimulates the hypothalamic thirst center of the brain as well as promoting the release of ADH from the posterior pituitary. When the blood lacks sufficient water, plasma osmolarity is increased and these shrink.