Fluid & Electrolytes Lab Values

Fluid & Electrolytes Lab Values

  • Sodium (Na+): 136 - 145 mEq/L

  • Potassium (K+): 3.5 - 5.0 mEq/L

  • Magnesium (Mg++): 1.3 - 2.1 mEq/L

Hemoglobin (Hgb)

  • Carries oxygen to the body, tissue, organs.

    • Male: 14 - 18 g/dL

    • Female: 12 - 16 g/dL

Hematocrit (Hct)

  • Percentage of blood made up of RBCs.

    • Male: 42 - 52%

    • Female: 37 - 47%

Blood Urea Nitrogen (BUN)

  • 10 - 20 mg/dL

  • Tells us about kidneys.

Creatinine

  • Accurate test to test kidney function.

    • Male: 0.6 - 1.2 mg/dL

    • Female: 0.5 - 1.1 mg/dL

    • Therapeutic = 1.0 mg/dL

  • High Cr = renal failure/injury

Kidneys

  • Critical for fluid & electrolyte balance.

Fluid Balance

  • Water volume in the body can be intracellular or extracellular.

    • Intracellular = water inside cells

    • Extracellular = outside cells

      • Interstitial = space between cells, not in blood

      • Plasma = serum

  • Electrolytes can affect fluid balance, and fluid balance can affect electrolytes.

  • Plasma volume = a small proportion of total water volume.

  • Adequate plasma volume maintains blood pressure and tissue perfusion

Perfusion

  • Delivery of blood to the capillary bed of an organ or tissue

Ischemia

  • Reduction in blood supply to any tissue or organ, causing a shortage of oxygen

  • Fluid balance = fluid intake – fluid output

  • Urine output = fluid volume status

Water Loss

  • Kidney is the most important and most sensitive water loss route because it is regulated and adjustable.

Kidney Functions

  • Endocrine functions

  • Metabolic waste excretion

  • Control of solutes and fluids where kidney filters extra electrolytes &/or fluids

  • Blood pressure control

  • Drug metabolism

  • Acid/base balance and excretion

  • Kidneys = sensitive to fluid volume

  • Dehydrated = kidneys puts out less water = concentrated urine

Hormones Regulating Fluid and Electrolyte Balance

  • Aldosterone

  • Anti-diuretic hormone (ADH)

  • Natriuretic peptides (ANP & BNP)

Aldosterone

  • Reabsorbs sodium & water in kidneys.

  • The RAAS system is triggered by decreased tissue perfusion to the kidneys

  • Leads to the retention of water and sodium & increases blood volume and blood pressure

  • Critical for BP & fluid volume

  • How to know if you have low perfusion:

    • Low BP = low perfusion

    • Low blood volume; if the blood volume is too low = bad perfusion

    • Ischemia = low blood oxygen

  • Poor perfusion = kidneys sendse a drop in bp —> release of renin —> angiotensin —> angio 1 —> A.C.E —> angio 2 = causes vasoconstriction (which increases blood pressure) —> stimulates aldosterone secretion (from the adrenal gland) —> leading to aldosterone promoting the reabsorption of sodium and water to the kidneys, further increasing blood volume & BP.

Anti-diuretic Hormone (ADH)

  • Aldosterone holds onto reabsorbed sodium andwater in the kidneys while ADH is only go ing to reabsorb water (DOES NOT REABSORB SODIUM)

  • ADH is NOT triggered by the kidneys

  • triggered by the change in blood osmolarity

  • when solute concentration increases our osmolarity increases our blood becomes more concetratede bc of a decrease in blood volume

  • will trigger the pituitary gland to release ADH

  • ADH goes to kidneys and tells the kidneys to let them reabsorb water

    *once water has been reabsorbed its going to increase blood volume while also decreasing the osmolarity back to its normal range.

Natriuretic Peptides (BNP, ANP)

  • Hormones released from the heart in states of fluid volume overload (when the heart stretches it causes the release of hormones).

  • Helps decrease fluid volume

  • ANP released from atria, BNP released from ventricles

  • Lead to vasodilation = results in decreased BP

  • Natriuresis (sodium excretion)

  • Diuresis (water excretion)

  • BNP is tested in the hospital frequently to check for lfuid volume overload which is usually realted to heart failure.

  • with too much fluid/volume we want to get rid of mit and also vasodilate so there is less pressure.

  • we vasodilate, natriuresis (get rid of sodium) & diuresis (get rid & increase urine production) = will help decrease BP & manage the excess fluid volume.

Fluid Volume Overload

  • Edema, tight, weeping, no skin turgor

  • Hypertension

  • Tachycardia (bounding pulse)

  • Weight gain

  • Crackles, cough

  • Decrease in H&H, diluted

  • Hyponatremia

  • JVD

  • Clear, normal increase in urine

Fluid Volume Deficit

  • Increase thirst

  • Tachycardia (thready pulse)

  • Dry mouth & skin, tenting

  • Hypotension

  • Dizziness (from lack of perfusion)

  • Increase in H&H, concentrated

  • Hypernatremia

  • Decrease in urine, concentrated

  • oliguria

Electrolyte Imbalance

  • Intake: food/diet

  • Output: kidney excretion or reabsorption

  • Cause: Change in fluid intake/output

    • Actual loss of electrolytes or retention

  • Risk factors:

    • Elderly

    • Chronic kidney disease

    • Endocrine disorders

    • Drugs that alter fluid/electrolyte balance

      • ex. diuretics

Sodium (Na+)

  • 136-145 mEq/L

  • Important for nerve conduction

  • EXTRACELLULAR (found outside the cell)

  • responsible for:

    • Muscle contraction

    • Cardiac muscle contraction

    • Nerve impulses (big effect on CNS)

    • Water distribution (helps maintain plasma volume and BP)

  • Intake: diet/food

  • Output: kidney excretion or reabsorption

  • Regulated by:

    • ADH

    • RAAS

    • Natriuretic peptides

    • Thirst mechanism

Hyponatremia

  • < 136 mEq/L

  • Etiology:

    • Low sodium

    • Deficient sodium intake

    • Loss of body fluids (wound drainage w/ burn victims = must drink electrolytes)

    • Water Gain: Hypervolemia (gain of too much fluid; the body becomes fluid volume overloaded and the blood gts diluted down)

  • H&H decreases

  • S/S:

    • CNS: Confusion, Seizure, Coma & death

    • Muscular: Weakness, Decreased reflexes

    • GI: Nausea & vomiting, Diarrhea

  • Treatment:

    • Sodium loss: Hypertonic IV fluids, Nutritional therapy

    • Water gain: Fluid restriction, Diuretics/dialysis

Hypernatremia

  • > 145 mEq/L

  • Etiology:

    • Sodium gain: Excessive sodium intake can be caused by Kidney failure

    • Water loss: Hypovolemia (dehydration)

  • Hgb increases (blood volume becomes more concentrated)

  • Pts usually on NPO or tube feedings

  • S/S:

    • CNS: Confusion, Agitation, Lethargy / coma

    • Muscular: Twitching progressing to weakness, Decreased reflexes

    • GI: Constipation

  • Treatment:

    • Sodium gain: Nutritional therapy, Diuretics/dialysis

    • Water loss: Ensure adequate water intake, Isotonic or hypotonic IV fluids

Dietary Sources of Sodium

  • Most Americans consume too much sodium

  • Salty Six (foods that can add high levels of sodium):

    • Breads & Rolls

    • Pizza

    • Sandwiches

    • Cold Cuts & Cured Meats

    • Soup

    • Burritos & Tacos

Potassium

  • 3.5-5.0 mEq/L

  • Intracellular (most inside the cell) cation responsible for:

    • Muscle contraction

    • Cardiac muscle contraction

    • Critical = can cause dysrhythmias

    • Nerve impulses

    • Regulation of acid-base balance

  • Intake: diet

  • Output: kidney excretion or reabsorption

  • Sodium is affected by fluid volume status, not potassium or magnesium since its intracellular

Hypokalemia

  • < 3.5 mEq/L

  • Etiology:

    • Deficient intake (not enough potassium in diet)

    • Loss of body fluids (ex. vomiting or diarrhea)

    • Medications (diuretics, insulin)

    • Hypomagnesemia (potassium needs magnesium)

      • Can cause hypokalemia, but no the other way around

  • S/S:

    • Cardiac: dysrhythmias / tachyarrhythmias & shallow respirations

    • CNS: lethargy and confusion

    • Muscular: weakness, paralysis, shallow respirations

    • GI: nausea, vomiting, constipation, paralytic ileus (when stool becomes paralyzed and doesn’t move through bowel)

  • Watch out for cardiac changes in pts w/ potassium balances high/low

  • Treatment:

    • Correct cause (give tablets or IV solution of potassium)

    • Potassium replacement (need HCP order & can use throughout stay as long as it’s appropriate)

    • Nutritional therapy

    • Cardiac and respiratory monitoring

Hyperkalemia

  • > 5.0 mEq/L

  • Etiology:

    • Excessive intake

    • Kidney failure

    • Tissue/crush injury

      • When this happens, potassium is released into the plasma causing hyperkalemia

  • S/S:

    • Cardiac: dysrhythmias / bradycardia

    • CNS: irritability and anxiety

    • Muscular: twitching, progresses to weakness, paralysis

    • GI: diarrhea, increased bowel sounds

  • Treatment:

    • Correct cause

    • Diuretics/ dialysis

    • Sodium polystyrene sulfonate (Kayexalate)

    • Potassium exits

    • Insulin / glucose

      • Give together if higher dose of insulin not for DM

    • Nutritional therapy

    • Cardiac monitoring

High Potassium Foods

  • Fruits

  • Vegetables

  • Others: Breakfast Drinks, Ensure/Boost, Coconut Milk, Molasses, Salt Substitute (made from potassium, beware if low sodium & potassium)

Administration of Intravenous Potassium

  • Give carefully!

  • Hyperkalemia can cause fatal cardiac dysrhythmias

  • NEVER give IV push > 5.0

  • Give slowly, no faster than 10mEq/hr

  • ALWAYS use a pump (no drip rate)

  • Can be irritating to the veins

Magnesium

  • 1.3-2.1 mEq/L

  • Intracellular cation responsible for:

    • Muscle contraction

    • Cardiac muscle contraction

    • Carbohydrate metabolism

    • Absorption of potassium

  • Intake: diet

  • Output: kidney excretion or reabsorption

Hypomagnesemia

  • (< 1.3 mEq/L)

  • Etiology:

    • Deficient intake

    • Malnutrition

    • Alcohol abuse

    • Loss of body fluids

    • GI diseases

    • Medications

  • S/S:

    • Cardiac: Dysrhythmias

    • CNS: Agitation, Confusion

    • Muscular: Increased reflexes, Numbness & tingling

    • GI: Constipation, Paralytic ileus

  • Treatment:

    • Magnesium replacement

    • Check and replace calcium and potassium

    • Nutritional therapy

    • Cardiac monitoring

Hypermagnesemia

  • > 2.1 mEq/L = helps you relax (to remember sx)

  • Etiology:

    • Excessive intake

    • Magnesium containing antacids/laxatives

    • Kidney failure

  • S/S:

    • Cardiac: Bradycardia, hypotension

    • CNS: Lethargy & drowsiness, Coma

    • Muscular: Decreased reflexes, Muscle weakness

    • GI: diarrhea

  • Treatment:

    • Diuretics

    • Dialysis

    • Nutritional counseling

    • Cardiac monitoring

Summary of Nursing Care

  • Monitor:

    • Labs

    • Vital signs

    • Cardiac rhythm

    • I&O

    • Weight

  • Administer medications properly

  • Educate:

    • Medications

    • Diet

    • Follow up with HCP

    • Signs and symptoms to report

  • Prioritization

    • Airway

    • Breathing

    • Circulation

    • Safety

    • Pain

  • Assess

  • Intervention

  • Reassessment