week 5- blood chemistry Flashcards
(91 cards)
What are normal and critical K values?
o Adult/Elderly: 3.5 – 5.2 mEq/L o Optimum: 4.0-4.5 o Child: 3.4 - 4.7 o Infants (7 d– 1 yr): 4.1-5.3 o Neonates (0-7 d): 3.7 - 5.9 o Critical Values: < 2.5; > 6.5 to 8.0 (depends on lab, text)
• What factors can interfere with K values?
o Hemolysis releases K+ from RBCs → ↑
o Cells sitting in serum, separate, → leakage of K+ from RBCs → ↑
o “Pumping” hand prior to venipuncture ↑ K+ (esp w tourniquet)
• What pts should have K monitored? Why?
o serious illness
o diuretics or heart medications
o Minor changes in serum concentration → major physiological consequences
• What can cause hyperkalemia? Value?
o Serum K+ > 5.5 mEq / L o renal dz o Massive cellular trauma o Insulin def o Addison’s dz o K sparing diuretics o ↓ blood pH o Exercise causes K+ to move out of cells
• What are clinical manifestations of hyperkalemia?
o Early: hypertonicity, paresthesia
o Late: Muscle weakness, flaccid paralysis
o Change in ECG pattern
o Dysrhythmias
o Bradycardia, heart block, cardiac arrest
• What can cause hypokalemia? Value?
o Serum K+ < 3.5 mEq /L
o DM: Insulin gets K+ into cell
o Ketoacidosis: H+ replaces K+ → lost in urine
o Β-adrenergic drugs, epi
o Decreased intake
o Increased K+ loss: chronic diuretics, acid/base imbalance, trauma and stress, ↑aldosterone, redistribution between ICF and ECF
• What are clinical manifestations of hypokalemia?
o Neuromuscular dos: weakness, flaccid paralysis, respiratory arrest, constipation o Dysrhythmias, U wave o Postural hypotension o Cardiac arrest o Glucose intolerance o Renal damage o ↑ BP in both normo and hypertensive
• What is work-up for hypo- and hyper-kalemia?
o Hypo: urine K, BP, aldosterone, plasma HCO3, renin
o Hyper: GFR, renal K excretion, aldosterone, renin
• What is Calcium’s role in body?
o 99% stored in bone and teeth, 1% ECF; very stable levels
o Nerve transmission, bone formation, enzymes (+P, Mg)
o 50% in serum is ionized, rest bound to protein (albumin) or salts
o Only ionized (=active form) for cardiac function, clotting, muscular contraction, nerve impulse transmission
• What are 3 main mechanisms of Ca2+ homeostasis? Other factors?
o PTH ↑ mobilization from bone (PTH inhibited by hypercalcemia)
o PTH ↑ renal reabsorption
o Active vit D ↑ absorption from intestines
o Calcitonin: from thyroid, bone formation, ↑ renal excretion
o Also: estrogens, androgens, blood pH
o Inverse relationship bw serum Ca2+ and P
• What are normal and critical Ca values?
o Adult: 8.8 - 10.4 mg/dl
o Child: Varies with age
o Optimum: 9.2 – 10.0
o Critical: < 7.0
• What causes hypercalcemia?
o Hyperparathyroidism o Hypothyroid o Renal dz o Excessive intake of vit D o Milk-alkali syndrome o drugs o Malignant tumors (products promote bone breakdown, in bone causes Ca leech) o Hypophosphatemia
• What are ssx of hypercalcemia?
o Nonspecific: fatigue, weakness, lethargy o ↑ kidney and pancreatic stones o Muscle cramps o Bradycardia, cardiac arrest o Pain o GI activity o Nausea, abdominal cramps o Diarrhea, constipation o Metastatic calcification
• What is work-up for hypercalcemia?
o CMP, vit D, PTH, TSH, ESR
• What are ssx of hypocalcemia?
o Hyperactive neuromuscular reflexes and tetany o Convulsions (severe)
• What causes hypocalcemia?
o Renal failure
o ↓ vitamin D
o ↓ parathyroid function
o ↑ calcitonin
o Malabsorption states
o Abnormal intestinal acidity and acid/ base balance
o Widespread infection or peritoneal inflammation
• What is the ionized calcium test?
o must be ordered specifically and separately
o NOT affected by serum albumin levels
o Mb more specific indicator of hyperparathyroidism than total __??
o For open heart and organ transplant surgeries
• What is magnesium’s role in the body?
o 50% in bone, 50% in cells of tissues/organs, 1% in blood (constant)
o Regulate blood sugar, normal BP, energy metabolism , protein synthesis
o Escreted in kidney
o >300 biochemical rxns
o Normal muscle/nerve fxn, heart rhythm, immune system, bones strong
• What is the Mg test?
o Not in CMP
o Separate test
• What is the significance of the hydration shells of Ca and Mg?
o Ca has 1, can shed it to fit into a structure
o Mg has 2, must shed 2, which consumes a lot of energy
• How are Mg levels maintained in body? Normal?
o absorbed in SI, some by LI (24%-76%) o more Absorbed when body levels are lo o Excreted in urine and feces o Renal excretion may vary from 0.5-70% o N= 1.8-3.0 mg/dL
• What are 4 ways to measure Mg?
o Serum Mg: most common, doesn’t rep body stores
o RBC levels: higher than serum, doesn’t rep body stores
o 24-hr urine: to asses Mg wasting by kidneys
o Mg retention: more sens than serum for true Mg def; detects bone def
• What causes hypomagnesemia?
o ↓dietary intake: malnutrition, malabsorption, chronic diarrhea
o ↑renal loss: Congenital or acquired tubular
o Drugs
o Endocrine: 1st and 2nd hyperaldosteronism, DM
o Other: stress, alcoholism, ↑ lactation, heat, ↑ exercise, burns
• What are ssx of hypomagnesemia?
o muscle irritability, contractility, tetany (neuromuscular integration)
o hyperactive DTRs
o ↑BP, dysrhythmias; or hypotension/tremor
o Positive Chvostek’s and Trousseau’s signs
o Memory loss, emotional lability, confusion, hallucinations, sz
o Often mistaken for hypokalemia, which can occur simultaneously