Case 1: Serum Lab Values Flashcards
What is serum?
Blood plasma lacking clotting factors
Substances that ionizes when dissolved in polar solvent.
Electrolytes
High sodium
hypernatremia
What causes hypernatremia?
Decreased total body water (burns, excessive sweating, diabetes insipidus), increased intake of sodium (diet/IV), or decreased renal clearance of sodium (hyperaldosteronism), Cushing Syndrome (excess cortisol; occurs with increased calcium).
Low sodium
hyponatremia
What causes hyponatremia?
Increased body water (excessive intake, CHF), decreased intake of sodium (diet/IV), or increased sodium loss (diarrhea, vomiting, renal insufficiency).
What is the major cation within the cell?
Potassium
What is the major extracellular cation?
Sodium
What can cause hypokalemia
Deficient dietary intake, deficient IV intake, burns, GI disorders, hyperaldosteronism, renal artery stenosis, trauma, surgery
How does renal artery stenosis cause hypokalemia?
It decreases renal blood flow, stimulating aldosterone, which leads to a loss of potassium
What symptoms can hypokalemia cause?
Decreased contractility in all types of muscle (weakness, paralysis, arrhythmias, colicky pain, etc)
What is the major extracellular anion?
Cl (primary purpose is to maintain electric neutrality with sodium)
True or false: Hyper/hypochloremia commonly occurs without any other serum chemistry abnormalities.
False; often occurs in parallel with shifts in bicarbonate or sodium levels
What can cause hyperchloremia?
Dehydration, metabolic acidosis (because loss of bicarb), Cushing syndrome (excess cortisol secretion; sodium will be too high as well)
How does chloride help buffer the blood?
When CO2 (and H+) levels in blood rise, bicarb moves from inside cells into blood to buffer. Chloride moves into the cells to maintain electrical neutrality
When aldosterone causes sodium reabsorption, ______ follows to maintain electrical balance.
chloride
TCO2 is the concentration of ____ ____ in the peripheral blood and uses ______ CO2, not arterial. It is essentially a measurement of ___________.
total CO2; venous; bicarbonate
________ is the second most important anion in extracellular blood in regards to electrolyte neutrality.
Bicarbonate
Most of the CO2 in blood is in the form of ________.
bicarbonate
Levels of bicarbonate are regulated by the _______.
Kidneys
Venous TCO2 blood values can give a rough estimate of bicarbonate concentration, but because they are affected by ____ in the laboratory are not very accurate. Primarily used as a rough guide for acid-base balance.
Air
Indications for measuring total CO2 (TCO2)?
1) Evaluate pH status
2) Assist in evaluating electrolytes
Indications for measuring serum chloride?
To assist in evaluating electrolytes
What are the indications for measuring serum calcium levels?
1) Evaluate parathyroid function
2) Evaluate calcium metabolism
3) Monitor patients with renal failure or transplantation, hyperparathyroidism, and certain malignancies.
4) Monitor calcium levels following blood transfusion.
What can cause elevated serum glucose?
Diabetes mellitus, stress, Cushing syndrome are most common
What can cause low serum glucose?
Insulinoma (insulin released without regard to biofeedback mechanisms), hypothyroidism, hypopituitarism, Addison’s disease (diminished cortisol production), liver disease, glycogen storage diseases, carnitine deficiency (or other block of beta oxidation), insulin overdose (most common)
What is creatinine used to evaluate?
Renal function (glomerular filtration rate)
True or false: Creatinine level is impacted drastically by hepatic function.
False
Decreased BUN can indicate___________.
Liver dysfunction (urea is synthesized in the liver), protein depletion, overhydration, pregnancy
Increased BUN can indicate_______.
Renal dysfunction (urea is excreted by kidneys), hypovolemia, CHF, MI, shock, burns, starvation (excess protein breakdown), sepsis
What would you get BUN levels to evaluate?
Renal and liver function, hydration status, protein breakdown
What would you order a serum creatinine to evaluate?
GFR of kidneys (kidney function)
What would high levels of serum Total Protein indicate?
Infection, inflammation, cancer, or dehydration
What can low levels of serum Total Protein indicate?
Kidney or liver disease, malnutrition, blood loss.
Total protein includes ________ and ______, which constitute most of the protein within the body.
Albumin and globulin