Lab values every nurse should know and why?
We go through a lot of labs in the hospital, they are all important but some are more important than others. We come up with a comprehensive list of the major lab values every nurse should know and why. 9 most important lab values
Levels in adults: 3.5-5.2 mEq/L, Children: 3.4-4.7 mEq/L
- Potassium is important in maintaining electrolyte balance. It aids in nerve function and muscle contraction. It also helps our heartbeat stay regular.
- We use potassium levels to assess acidosis, AKI, CKD, dehydration, and certain therapeutic interventions.
- Hyperkalemia: K > 5.2
- S&S: muscle weakness, nausea, vomiting, weakness, heart palpitations, cardiac dysrhythmias.
- Peaked T-waves, PR prolongation, and lose p waves.
- IV glucose and insulin, NaHCO3, diuretics, Kayexalate, and dialysis.
- Hypokalemia: K < 3.5
- S&S: Orthostatic hypotension, shallow respirations, confusion, decreased deep tendon reflexes (hammer on knee/elbow), loss of bowel sounds.
- Depressed ST, flat or inverted T waves, U wave
- IV/oral potassium, hold diuretics and digoxin.
- 1.8 – 2.5 mg/dL
- Magnesium plays a role in nerve function, transferring and storing energy, regulation of parathyroid hormone PTH (which also plays a role in calcium levels).
- Hypermagnesemia: Mg > 2.5
- S&S: lethargy, hypotension, Respiratory arrest, diminished deep tendon reflexes.
- Prolonged PR and QT, widened QRS
- IV calcium, diuretics, and dialysis
- Hypomagnesemia: Mg < 1.8
- Hypertension, irritability, hyperreflexia, and involuntary movements.
- Torsades de pointes
- Magnesium Sulfate, and Magnesium oxide.
- 135 – 145 meq/L
- Important in nerve impulses, intracellular osmolality, promotes myocardial, smooth, and skeletal contractility.
- Hypernatremia: Na > 145 meq/L
- S&S: restless, agitation, fluid retention, edema, decreased urine output.
- Isotonic or hypotonic solution (run slow because brain tissue is at risk for an intracellular fluid shift.
- Hyponatremia: Na < 135 meq/L
- S&S: seizure, stupor, confusion, orthostatic hypotension, spasms, cramping.
- Hypovolemic Hyponatremia: give IV sodium chloride infusion to restore sodium and fluids. Hypertonic solution cal also be given, 3% Saline.
- Hypervolemic Hyponatremia: Restrict fluid intake, diuretics to excretion the extra water rather than sodium to help concentrate the sodium.
- 8.6 – 10.3 mg/dL
- Helps regulate cardiac, smooth, and skeletal muscle contraction, impulse transmission, and cardiac automaticity and contractility.
- Hypercalcemia: Ca > 10.3
- Muscle weakness, disorientation, absent reflexes, and kidney stones.
- Shortened QT interval.
- Calcitonin, fluids, loop diuretics, IV bisphosphonates, and dialysis.
- Hypocalcemia: Ca < 8.6
- Confusion, hyperreactive reflexes, muscle spasms, positive Trousseau’s (blow up BP cuff wait 3 min, is arm contracts it is positive), and Chvostek (Chvostek sign is a contraction of facial muscles provoked by lightly tapping over the facial nerve anterior to the ear as it crosses the zygomatic arch)
- IV calcium Chloride, calcium gluconate
- 2.8 – 4.5 mg/dL
- Works as a buffer for acid-base balance, aids in muscle, neurological, and platelet function.
- Hyperphosphatemia: P > 4.5 mg/dL
- confusion, hyperactive reflexes, muscle spasms, positive Trousseau and chvostek.
- Phosphate binding drugs (PhosLo, removes P via stool), and dialysis.
- Hypophosphatemia: < 2.8 mg/dL
- Respiratory depression, rhabdomyolysis, osteomalacia (weakened bones), irritability, decrease platelet aggregation, and immune suppression.
- IV Na2PO4 with vitamin D
- 29 to 33 units/L for males and 19 to 25 units/L
- Part of the liver function test used to evaluate the liver.
- The highest concentrations are found in the liver and in smaller concentrations in kidneys, heart, spleen, pancreas, red blood cells, and skeletal muscle
- A very sensitive test can increase as much as 50x
- The rationale for the lab is to assess liver disease or damage.
- 20-40 units/L for males and 15-30 unit/L
- AST is an enzyme catalyst that is part of the Krebs cycle.
- AST exists in large amounts in the liver and myocardial cells, in smaller amount locate in skeletal muscle, kidneys, pancreas, brain, and red blood cells
- Used as an indicator of cellular damage in liver disease.
- 0.6–1.2 mg/dL
- Creatinine is a byproduct of creatine which is needed to produce the energy to contract our muscles.
- The kidney should normally be filtering out the substance.
- High creatinine
- This shows that there is an issue with kidney function.
- The glomerulus is doing a poor job.
- 7-21 mg/dL
- Measures the Blood Urea Nitrogen.
- Shows us how well the kidneys are functioning.
- When elevated it is a cause for concern.
- Can show kidney failure, shock, or heart failure.
- PT: 10-12 seconds
- INR: 0.9-1.1
- Prothrombin time and the International normalized ratio.
- PT/INR assesses the extrinsic and common pathways. This allows you the see how fast prothrombin gets turned into thrombin.
- Extrinsic: clot formation that is activated when there is an external injury resulting in blood loss.
- Intrinsic: clot formation that is activated when there is an internal injury.
- Common: where the intrinsic and extrinsic pathways meet from the clot.
- These labs show how fast your blood clots.