NCLEX Lab Values Made Easy: Nursing Review Guide

The human body maintains fluid and electrolyte balance through homeostasis, which is the maintenance of the internal environment according to changing external conditions. Each body cavity has a fixed concentration of fluid and electrolytes. Aldosterone hormone plays a crucial role in regulating this balance. Body fluid composition varies by age: approximately 60% of body mass is fluid in adults, while pediatric patients have approximately 80% fluid. Diffusion is the movement of solute from higher to lower concentration to maintain equilibrium, while osmosis is the movement of water across semi-permeable membranes. Isotonic solutions have the same concentration as body cells, resulting in no net water movement. Hypertonic solutions contain less water and are used to replace more electrolytes relative to fluid volume. Treatment decisions depend on the patient's condition, fluid and electrolyte levels, and the type of dehydration or overhydration present.

This video covers fundamental nursing concepts related to fluid and electrolyte imbalances, including IV infusion calculations using the formula Volume × Drip Factor ÷ Time, recognizing that adrenal insufficiency (Addison's disease) leads to hyponatremia with symptoms like diarrhea, abdominal cramps, and nausea; understanding that isotonic solutions like normal saline and lactated Ringer's expand vascular volume, while hypertonic solutions pull fluid from cells and hypotonic solutions move fluid into cells; identifying high-risk populations for dehydration (very young, very old, cognitively impaired); and recognizing that potassium-rich foods like bananas affect cardiac conductivity, calcium-rich foods like milkshakes impact blood clotting, and magnesium-rich foods like spinach influence neurochemical activity.

The human body maintains fluid balance through a complex system where total body water constitutes approximately 60% of body weight, distributed as 2/3 intracellular fluid within cells and 1/3 extracellular fluid in interstitial and intravascular spaces; this balance is regulated by mechanisms including ADH secretion, osmotic and hydrostatic pressures, and electrolyte concentrations, with key electrolytes like sodium, potassium, chloride, and calcium playing critical roles in maintaining cellular function, nerve conduction, muscle contraction, and acid-base balance, while disorders such as SIADH and diabetes insipidus demonstrate how dysregulation of these systems leads to clinical manifestations ranging from dehydration and edema to life-threatening cardiac and neurological complications.

The human body maintains fluid balance through a sophisticated system where intracellular fluid (approximately 60% of body weight in males, 50% in females) and extracellular fluid (plasma and interstitial fluid) are regulated by electrolytes, particularly sodium, which drives water movement across membranes; the body monitors plasma osmolality via hypothalamic osmoreceptors to trigger thirst and antidiuretic hormone release, while maintaining acid-base homeostasis (pH 7.35-7.45) through three defense mechanisms: chemical buffers (bicarbonate, proteins, phosphate), respiratory compensation (CO2 regulation), and renal excretion of metabolic acids.

The human body maintains life through precise fluid and electrolyte balance, with approximately 70% of body composition being water. Water serves critical functions including nutrient and oxygen transport, supporting muscle and brain function, and constituting 83% of blood volume. The six main electrolytes—potassium, sodium, chloride, calcium, phosphate, and magnesium—are dissolved substances that produce electrical charges (ions), enabling essential physiological processes: muscle contraction, nerve impulse transmission, bone formation, fluid balance through osmosis, and blood acid-base regulation. The kidneys regulate electrolyte balance through nephrons that filter blood and selectively reabsorb or excrete electrolytes. Sodium is primarily extracellular with normal range 135-145 mEq/L, while chloride works closely with sodium in fluid and acid-base balance. Understanding these fundamental principles is essential for recognizing and managing electrolyte disturbances in clinical practice.

The prefix 'hiper-' means increase or excess, while 'hipo-' means low or below. Examples include: hyperthermia (abnormal temperature increase), hyperplasia (increased cell number in tissue), hyperketonuria (excessive ketones in urine), hyperemia (increased blood flow); hypochondrium (region below cartilage), hyponatremia (low sodium in blood), and hypoventilation (decreased lung ventilation).

'Hyper-' means excessive or more than normal (e.g., hyperactive = moving too much). 'Hypo-' means below, less than, or under (e.g., hypodermic = under the skin). These prefixes indicate degree or amount.

Important medical prefixes include: Hyper (too much or above normal), Hypo (too little or below normal), Cardio (related to the heart), Neuro (related to nerves or brain), Gastro (related to the stomach), and Derm/Dermato (related to skin). For example, hypertension means high blood pressure (hyper = too much + tension = pressure), and hypoglycemia means too little sugar in the blood (hypo = too little + gly = sugar + emia = blood condition).

Medical prefixes indicate quantity or presence: 'hyper-' means increase or excess (e.g., hypertrophy for increased organ size, hyperlipidemia for high blood fats, hyperglycemia for high blood sugar). 'Hypo-' means decrease or deficiency (e.g., hypoglycemia for low blood sugar). 'A-' or 'an-' means absence (e.g., anemia for low blood, not absence of blood). The root 'hemo-' refers to blood, while the suffix '-emia' indicates a condition in the blood.

Hyper means 'excessive' or 'above' while hypo means 'deficient' or 'below'. These prefixes are used to describe conditions: hypertension (high blood pressure), hypotension (low blood pressure), hyperglycemia (high blood sugar), hypoglycemia (low blood sugar), hyperkalemia (high potassium), hypokalemia (low potassium).

Phlebotomy extracts blood for various diagnostic tests, as blood contains information about cells, biochemistry, and foreign invaders. Common tests include: Complete Blood Count (CBC) measuring blood cell types and amounts; Basic Metabolic Panel (BMP) assessing chemical balance including electrolytes and kidney function; Lipid Panel measuring cholesterol levels for heart disease risk; Hormone tests for thyroid, testosterone, or estrogen levels; Blood culture for identifying bacteria; and Antibody tests for infections. Multiple tests can be performed from a single blood draw. Test results require doctor interpretation considering medical history and symptoms for diagnosis and treatment planning.

The Basic Metabolic Panel (BMP) and Complete Blood Count (CBC) should be the foundation for learning lab values. For each component, paramedics should learn what it measures, what happens when values are abnormal, and the clinical significance. This foundational knowledge can then be extended to more complex labs like coags, enzymes, and autoimmune markers.

Blood tests are essential diagnostic tools for assessing health conditions including cholesterol, vitamin deficiencies, organ function, infections, diabetes, and cancer. The Complete Blood Count (CBC) measures RBCs (oxygen carriers), WBCs (immunity), platelets (clotting), hemoglobin, and hematocrit. The Basic Metabolic Panel (BMP) checks glucose, calcium, sodium, potassium, bicarbonate, chloride, BUN, and creatinine, requiring 8 hours fasting. The Comprehensive Metabolic Panel (CMP) adds liver enzymes (ALP, ALT, AST) and bilirubin to assess liver function and red blood cell breakdown. The Lipid Panel measures HDL (good cholesterol that removes toxins) and LDL (bad cholesterol that deposits in blood vessels, increasing heart disease risk). The Thyroid Panel evaluates T4, T3, and TSH hormones to assess thyroid function.

The Complete Blood Count (CBC) is a routine screening test for symptoms like unusual bleeding, persistent infections, and fatigue. Key findings include decreased hemoglobin indicating fatigue, thrombocytopenia causing excessive bleeding, neutrophilia suggesting infection, lymphocytosis indicating blood cancers like leukemia, and reticulocytosis associated with blood loss. The metabolic panel includes FBS for diabetes diagnosis (normal 70-100 mg/dL, prediabetes 100-125 mg/dL), BUN-creatinine ratio for renal function assessment, and AST/ALT for liver inflammation. These tests form the foundation of basic diagnostic screening in medical practice.

Blood work analyzes health through a small sample, revealing how wonderfully we are made. Before testing, patients may fast, drink water, or exercise. Blood is collected in tubes (at least 10ml) and sent to labs. Three main tests exist: CBC for blood cells, BMP for organ function and electrolytes, and CMP for liver function. Blood work evaluates organ health, diagnoses diseases, and identifies heart disease risks, but cannot definitively diagnose diseases due to variability—blood work captures only 80% of the population. White blood cells (3.5-10.5) are the body's defense army: neutrophils (40-60%) fight bacterial infections first; lymphocytes (20-40%) combat viruses and cancers; monocytes (7% or less) respond to infections and cancers; eosinophils (2% or less) indicate allergies; basophils respond to allergens and parasites. Red blood cells (3.77-5.28) carry oxygen via hemoglobin (13.5-17.5 men, 12.5-16.5 women). Hematocrit (34-47) measures hemoglobin content. MCV (80-100) measures cell size—too big or small impairs oxygen transport. MCH (26-37) and MCHC (31-36) measure hemoglobin content. RDW (12-15%) over 15% indicates iron deficiency. Platelets (150-380) act as plugs at injury sites; high counts increase clotting risk, low counts increase bleeding risk. The Basic Metabolic Panel evaluates kidney function through GFR (over 90 ml/minute normal), BUN (7-24 mg/dL), and creatinine (0.6-1.2 mg/dL). Electrolytes are essential: sodium (134-144 mEq/L) maintains blood pressure; potassium (3.5-4.5 mEq/L) is critical for heart function (over 7 is emergency); chloride (95-103 mEq/L) follows sodium; calcium (8.4-10.5 mg/dL) is essential for nerve function; magnesium (1.7-2.2 mg/dL) is involved in over 400 body processes. Blood glucose (70-90 mg/dL) normal; fasting over 125 mg/dL twice indicates diabetes. Hemoglobin A1c measures average blood glucose over 90 days: 4.8-5.6% normal, 5.7-6.4% pre-diabetic, over 6.5% diabetic. Levels over 10% typically require insulin therapy. Insulin acts as a key opening cell doors for glucose entry. Type 1 diabetes involves no insulin production; Type 2 involves insulin resistance. Normal insulin is 2.6-24.9 mcU/mL; over 10 indicates insulin sensitivity issues. Ideal is 4-5 mcU/mL. Normal pancreas secretes 20-50 units daily. The Complete Metabolic Panel evaluates liver function and serum proteins. The liver detoxifies, produces cholesterol, metabolizes amino acids, stores vitamins, and synthesizes proteins. Total protein (6-8.5 g/dL) ideal is 6.5-7.5 g/dL; high protein may indicate dehydration, cancer, or liver disease. Albumin (2.3-5.0 g/dL) carries calcium and buffers blood pH. Globulins include immunoglobulins for immune function and heptoglobin for waste removal. Bilirubin (0-1.2 mg/dL) causes jaundice when elevated; over 5-8 mg/dL causes yellow skin and eyes. Alkaline Phosphatase helps distinguish liver from bone problems. AST (0-40 IU/L) and ALT (0-32 IU/L) are liver enzymes elevated in hepatitis, fatty liver, and muscle damage. GGT (0-60 IU/L) indicates fatty liver, alcohol use, or gallbladder disease. Iron requires transport proteins (transferrin, 250-350 mcg/dL) and storage proteins (ferritin). Iron normal is 27-139 mcg/dL; ideal is 80-100 mcg/dL. Ferritin saturation (15-55%) measures iron storage; low levels indicate iron deficiency.