Biochem assessment Flashcards
purpose of lab testing:
diagnose disease/illness, support nutr diagnoses, evaluate med effectiveness, evaluate NCP interventions/response to med nutrition therapy, reflect acute or chronic change depending on situation
most common biochem tests
blood, tissue, urine, stool/fecal
less common biochem tests
saliva, sweat, breath tests, hair and nails
plasma without clotting factors
serum
main component of blood that consists of water, proteins, electrolytes, ions, clotting factors
plasma
these cells carry O2 and CO2
RBC
small blood cells that assist in blood clotting by forming a plug/clot at site of damage
platelets
part of the immune system and function in immune response, includes neutrophils/eosinophils/basophils/lymphocytes/monocytes
white blood cells
____ is liquid and cell free part of blood that has been treated with anticoagulants; ___ is liquid part of blood after coagulation
plasma; serum
serum = plasma - ____
fibrinogen
limitations of blood analysis
only reflects nutrient lvl of fluid or tissue sampled and may not reflect overall nutr status (ie. calcium)
two compartments of body’s metabolically available protein:
somatic (75%), visceral (25%)
what is somatic protein?
located within skeletal muscle, homogenous protein pool
what is visceral protein?
located in body’s organs, blood cells, serum proteins; composed of hundreds of diff proteins serving structural and functional roles
somatic + visceral proteins = ___% of total body protein
30-50
where is remaining protein (not metabolically active)?
skin, connective tissue
how is assesment of protein status nutr relevant?
help diff between malnutrition related to disease related inflammation vs starvation (chronic low intake), central to diagnosis of PEM
traditional/classical way of classifying nutritional status:
kwashiorkor, marasmus, marasmic kwashiorkor
PEM that is principally protein deficiency
kwashiorkor
PEM that is predominantly energy deficiency
marasmus
combo of chronic energy and protein deficits
marasmic kwashiorkor
nitrogenous by-product of muscle creatine phosphate for energy metabolism and skeletal muscle contraction, excreted in urine, only abnormally low lvls true indicator of muscle stores
creatinine
how to calculate Creatinine Height Index?
(24h urine creatinine (mg) x 100) / expected 24 urine creatinine
what is nitrogen balance?
muscle protein synth = muscle protein breakdown
factors promoting muscle protein synthesis
substrate (protein, leucine, kcal), activity stimulus, hormones (insulin, growth factors)
factors promoting muscle protein breakdown
inflammation, acute/chronic illness, immobilization/inactivity, low nutrient availability, meds
N2 Balance =
protein intake (g/24h) / 6.25 - urinary urea nitrogen (g/24h) - 4
assumptions of N2 balance calculation:
protein = 16% N, general estimate of N2 losses from skin and stool is 4 g
primary serum proteins
albumin, transferrin, prealbumin, retinol-binding protein
primary serum proteins also called:
negative acute phase reactants (aka not in time of stress/inflammation)
why measure serum proteins?
assessing protein and nutr status, determining patient risk for developing med complications, evaluating response to nutr support
when a.a. supply low, liver serum protein synthesis ___
decreases (so v serum markers = indirect measure of nutr status)
caveat in serum protein measures?
in inflammation, priority shift to synth acute phase reactance proteins to support inflamm response, synth of neg acute phase proteins is decreased –>slow serum proteins like albumin not a good indicator of nutr status but rather a reflection of disease
what is sensitivity?
true positive rate, measurement of proportion of actual positives that are correctly identified as such
what is specificity?
true negative rate, measurement of proportion of actual negatives that are correctly identified as such
most familiar and most abundant serum protein
albumin
part of the extracellular fluid between cells
interstitial fluid
other component of ECF that isn’t IF?
blood plasma
most of the water in body is ___
intracellular fluid
primary functions of albumin:
maintain colloidal osmotic pressure, transport molecule for enzymes, f.a., hormones, bilirubin
serum albumin is altered by:
acute inflamm, disease staets/clinical conditions, leakage from intravasc to extravasc spaces, blood loss, fluid resuscitation, shock state
albumin is ___ indicator of morbidity, mortality, severity of illness
prognostic (hypoalbuminemia –> ^ LOS, morbidity, mortality)
transferrin is primarily found in ____ and its function is to :
intravascular body pool; binds and transports iron in plasma (synth of transferrin inversely related with body’s iron stores, ^ transferrin means early iron deficiency, last lab value return normal when iron deficiency corrected)
when unable measure transferrin directly, can be measured indirectly via:
total iron binding capacity (TIBC) , which is an equation based measurement to predict transferrin
transport protein for thyroxine (T4) and carrier for retinol-binding protein with a short half life and small body pool
prealbumin
is prealbumin more or less sensitive indicator of nutr status than albumin?
more
when complexed with prealbumin, acts as a carrier to retinol and responds quickly to protein energy deprivation
retinol-binding protein
transferrin levels increase in ____ and decrease in ____
pregnancy, estrogen therapy, acute hepatitis; protein losing enteropathy and nephropathy, chronic infection, uremia, acute catabolic states
prealbumin levels increase in _____ and decrease in ____
CKD on dialysis; acute catabolic states, after surgery, hyperthyroidism, protein-losing enteropathy
RBP is increased in ___ and decreased in ___
renal disease; vitamin A deficiency, acute catabolic states, after surgery, hyperthyroidism
what is CBC?
complete blood count
what is incorporated in CBC?
red blood cells, white blood cells, platelets
in CBC lab chart, top value is ___ right value is ___ bottom value is ___ and left value is ___
Hgb; Plt; Hct; WBC
possible etiology of v RBC
hemorrhage, hemolysis, diet deficiency, genetic aberrations, marrow failure, chronic illness, organ failure
low values of Hb is < ___ in males and < ___ in females
130g/L; 120 g/L
causes of low hemoglobin
anemia, hemorrhage, hemolysis, cancer, nutr deficiencies, lymphoma, systemic lupus, sarcoidosis, kidney disease, sickle cell anemia
causes of high hemoglobin
congenital heart disease, polycythemia vera, hemoconcentration of blood, COPD, CHF, severe burns, dehydration
measure of the % of total blood volume that is made up by the RBCs
hematocrit
how to test hematocrit
ht of RBC column measured after centrifugation, ratio of height of RBC column compared to total blood column
what causes decreased Hct?
anemia, hyperthyroidism, cirrhosis, hemolytic reaction, hemorrhage, diet deficiency, malnutrition, bone marrow failure, pregnancy, rheumatoid arthritis, multiple myeloma
what causes incrased Hct (polycythemia)?
congenital heart disease, polycythemia vera, erythrocytosis, severe diarrhea, burns, dehydration, COPD, eclampsia
rbc indices provide info about _____ of RBCs
size, weight, Hgb concentration
what are the RBC indices?
mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular Hgb concentration, red blood cell distribution width
measure of the average volume (size) of a single RBC, used in classifying anemias
mean corpuscular volume
examples of microcytic
iron deficiency anemia and thalassemia
examples of macrocytic
vitamin B12, folate deficiencies
indication of variation in RBC size, calculated using MCV and RBC values, variations in this may be helpful in classifying certain types of anemias, indicator of anisocytosis, blood condition characterized by RBC’s of variable and abnormal size
red blood cell distribution width
most common cause of anemia worldwide
iron deficiency
iron deficiency occurs when:
ingestion/absorption of dietary iron is inadequate to meet losses (aspirin, menstruation, blood donations); unable meet requirements (rapid growth)
biochem indicators of iron status
serum iron, ferritin, sluble transferrin receptor, TIBC and transferrin, erythrocyte protoporphyrin
primary intracellular iron storage protein, most sensitive indicator of early iron deficiency, acute phase protein ^ during inflammation
ferritin
serum concentration of ___ directly proportional to body’s requirement for iron, esp in the erythrocyte producing cells of bone marrow
sTfR (soluble transferrin receptor)
serum sTfR ^ in ____
early iron deficiency before anemia develops
synth of tranferrin is ____ correlated with body’s iron stores
inversely
precursor of heme
protoporphyrin (accumulates in RBC when iron not available)
first stage of iron deficiency:
depleted iron stores, decreased serum ferritin
second stage of iron deficiency
early functional iron deficiency without anemia, decreased serum transferrin, ^ protoporphyrin, ^ sTfR, low end of normal Hgb
third stage of iron deficiency
iron deficiency anemia, v Hgb/ferritin/transferrin/MCV, ^ protoporphyrin/TIBC/sTfR, microcytic hypochromic anemia
what is anemia of chronic disease? (ACD)
during acute phase response, iron studies are altered (must differentiate this from IDA)
in IDA, serum ferritin is ___ while ACD it is ___
v ; ^ or normal
in IDA, TIBC is ___ and ACD it is ____
^ ; v or normal
transferrin saturation (extent to which transferrin is saturated with Fe) is more significant in decrease for IDA or ACD?
IDA
serum iron is affected by:
significant diurnal variation
RDW is ___ in IDA and ___ in ACD
^; normal (rises early in IDA)
MCV in IDA is ___ and in ACD is ____
v ; normal usually
sTfR is __ in IDA and __ in ACD
^ ; normal (sensitive test)
accumulation of excess iron in body tissues:
iron overload
iron overload usually result of :
hemochromatosis (group of genetic diseases characterized by excessive intestinal iron absorption and deposition of excessive iron in parenchymal cells with eventual tissue damage)
what are parenchymal cells?
essential to framework of tissue of organ
other cause of iron overload
multiple blood transfusions, excessive intake of iron fortified foods and supplements
two components of wbc count:
WBC count and differential count
what is diff. count?
measures percentage of each type of leukocyte present in the same specimen
v WBC (leukopenia) found cuz;
drug toxicity, bone marrow failure, infections, diet deficiency, autoimmune disease, bone marrow infiltration, congenital marrow aplasia
^ WBC (leukocytosis) found cuz:
infection, inflammation, trauma, stress, leukemia neoplasia, tissue necrosis
essential for blood clotting
platelets
reasons for v Plts:
hypersplenism, hemorrhage, immune thrombocytopenia, leukemia, inherited thrombocytopenia, disseminated intravascular coagulation, systemic lupus, pernicious anemia, hemolytic anemia, cancer chemo, infection
^ platelets (thrombocytosis) cuz:
malignant disorder, polycythemia vera, post-splenectomy syndrome, rheumatoid arthritis, iron deficiency anemia
chem blood tests are used in the detection of:
electrolyte balance, organ status, disease diagnosis and management
basic metabolic panel consists of these 8 test:
sodium, potassium, CO2 (bicarbonate), chloride, calcium, blood urea nitrogen, creatinine, glucose
basic metabolic panel provides info about:
kidney function, resp status, electrolyte balance, acid base balance, blood glucose
typical lab charting format for basic chem panel:
Na (top left) Cl (top mid) BUN (top right) Glc (right) K (bottom left) CO2 (bottom mid) Cr (bottom right)
comprehensive metabolic panel also has:
albumin, total protein, alkaline phosphatase, alanine amino transferase, aspartate amino transferase, bilirubin
electrolyte panel:
Na, K, Cl, Co2
renal panel
basic metabolic, Ca, Mg, glc, alb, total protein, P, creatinine clearance, eGFR
liver panel
liver enzymes (ALP, ALT, ASP, GGT), bilirubin, albumin, total protein, prothrombin time
lipid profile:
total cholesterol, HDL, LDL, TG
thyroid function:
TSH, free T4, free T3
minerals with electric charges that dissociate into solution into positively or negatively charged ions
electrolytes
electrolytes essential for:
maintain physiologic body functions, cell metabolism, neuromuscular, osmotic equilibrium
extracellular cations:
sodium and calcium
intracellular cations
K and Mg
extracellular anions:
CO2, Cl
intracellular anion
P
in Na/K ATPase, ___ Na is exchanged with ___ K
3; 2
most sodium is lost from ____
urine
balance of Na is maintained thru ____ from ____
aldosterone ; adrenal cortex
S/S of hyponatremia
headache, lethargy, restlessness, decreased reflexes, seizures, coma (found in 25% of hospitalized pt)
3 basic causes of hyponatremia
hypertonic hyponatremia, isovolemic hyponatremia, hypervolemic hypotonic hyponatremia
S/S for hypernatremia:
lethargy, thirst, hyperreflexia, seizures, coma, death
potential cauuses for hypernatremia
^ Na intake, v Na losses, excessive free body water loss
S/S for hypokalemia:
muscular and generalized weakness, cramping in extremities, vomiting, arrhythmias, cardiac arrest
potential causes of hypokalemia
large vol losses, refeeding syndrome, insulin delivery, excessive losses thru urine (med related), diabetic ketoacidosis, deficient intake
S/S of hyperkalemia:
muscle weakness, paralysis, resp failure, arrhythmias, cardiac arrest
potential causes hyperkalemia:
acute/chronic renal failure, excessive intake, aldosterone inhibiting diuretics, crush/cell damage injuries, hemolysis, acidosis, dehydration
primary functions fo calcium not in bone:
electroconductivity of cell, bone metabolism, BP, blood clotting
about half of Ca in intravascular compartment is bound to ___
albumin
what is equation for corrected Ca?
serum Ca + 0.8 (4-serum albumin)
S/S for hypocalcemia:
numbness, tingling, hyperactive reflexes, tetany, lethargy, muscle weakness, confusion, seizure
potential cause for hypocalcemia:
hypoparathyroidism, renal failure, hyperphosphatemia 2ndary to renal failure, vit D deficient, osteomalacia, malabsorption, alkalosis
S/S of hypercalcemia:
lethargy, nausea, vomiting, muscle weakness, depression
potential causes of hypercalcemia:
hyperparathyroidism, cancer with PTH producing tumours, excessive intake vit D/milk/antacids, Addison disease, granulomatous infections
second most prevalent intracellular cation, 70% free/ionized in serum
Magnesium
primary functions of Mg
cofactor in enzyme reactions, important in bone, CNA, cardiovasc
___% Mg absorbed in small intestine, regulated by ______
30-50; intestine, kidney, bone
S/S of hypomagnesemia
muscle weakness, tetany, ataxia, nystagmus, ventricular arrhythmia
potential causes of hypomagnesemia:
malnutrition/malabsoprtion, refeeding, hypoparathyroidism, alcoholism, chronic renal tubular disease, diabetic acidosis, excess loss from fluids, cirrhosis
S/S of hypermagnesemia
nausea, vomiting, muscle weakness, reduced resp, hypotension, decreased heart rates, cardiac arrest
potential causes of hypermagnesemia
renal insufficiency, addison disease, hypothyroidism, dehydration, use of Mg containing antacids or salts
S/s of hypophosphatemia
impaired cardiac fxn, reduced diaphragm contractions, confusion, decreased tissue o2 delivery, coma, death
potential causes of hypophosphatemia:
malnutrition, refeeding, hyperparathyroidism, hypercalcemia, hyperinsulinemia, IV clucose administration, chronic alcoholism, NG suction, vomiting
S/S hyperphosphatemia
muscle cramps , tetany, numbness/tingling, bone/joint pain, pruritus, rash
potential causes of hyperphosphatemia
renal failure, hypoparathyroidism, acromegaly, addison, bone metastases, sarcoidosis, hypocalcemia, rhabdomyolysis, healing fractures, hypervitaminosis D
functions of water
transport nutrients, transport and excrete metabolic waste, support cell shape/structure, lubricate, sustain body temp
TBW makes up ____% of body wt in healthy, lean adults and is influenced by:
50-70; sex (less in f), fat/lean mass (less in fat)
3 types of ECF
interstitial, intravascular, transcellular
third spaces?
peritoneal, pericardial, thoracic cavities, joints and bursae
fluid move between compartments via:
osmosis (mvmt water only) and filtration (water and solutes)
what is osmosis?
mvmt of fluid across semipermeable mem from area low concentration of solute to area of high concentration
what is osmotic pressure?
force that pulls water across mem; based on # solute particles in solution
solutes that do not disperse in fluid
colloids
_____ exerts greatest effect on colloidal oncotic pressure
serum albumin
pressure exerted by fluid on membrane
hydrostatic
when hydrostatic pressure differs on 2 sides of me, fluid goes from area of ____ pressure to place of ___ pressure
high; low
osmotic pressure can be expressed as either ____ or ____
osmolarity (number of osmols per L of solution) and osmolality (number of osmols per kg/solvent)
fluids with osmolality equal to blood - ___
isotonic
osmolality estimated using serum concentrations fo ____
Na, K, glc, urea
sensible losses of fluid thru ___ and insensible thru ____
urine, sweat, feces; lungs, evaporation
average healthy adult fluid requirement:
30-35ml/kg
sample calcs for est fluid requirements;
1 mL of fluid per kcal, 30-35ml/kg, 1 mL/kcal + 100 mL/g N, 1500 mL/m^2
how to calc BSA:
square root of htxwt, / by 3600
3 categories of altered fluid balance:
changes in fluid volume, changes in fluid concentration, changes in fluid composition
what is hypovolemia?
extracell fluid deficit, usually renal/extrarenal fluid loss
treat hypovolemia?
replete w/ fluid and Na slowly
Na concentration is used to determine ____
ECF osmolality
fluid deficit equation:
(%age of body water x wt) x (serum Na - 140) / serum Na
hypervolemia means ____ and in this setting, fluid shifts into ____
excess ECF; interstitial spaces
shift of fluid into interstitial spaces is called:
edema
hypervolemia is caused by:
decrased urine output, excess IV fluids. excess vasopressin secretion
most common alterations in osmolality:
Na or hyperglycemia (shift of water without shift in solute)
hyponatremia usually caused by:
Na restriction and diuretic use (hypervolemic hyponatremia, hypovolemic hypotonic hyponatremia, hypertonic hyponatremia)
this type of hyponatremia caused by excess total body water without increase in Na, mostly treated by water restriction
hypervolemic hyponatremia
this type of hyponatremia is characterized by a deficits in total body water and Na, primary treat by calculating fluid deficit and replacing half fluid deficit in first 24 hr and correct Na slowly
hypovolemic hypotonic
fluid and Na loss can occur in:
excess sweating, GI loss, wound drainage/burns, excess diuretics, stomach resections
why need to slowly Na correct in hypovolemic hypotonic?
cuz prevent osmotic demyelinating syndrome
this type of hyponatremia is found in setting of increased plasma solute (usually hyperglycemia)–>^ in gluc cause water from ICF to ECF and Na is diluted
hypertonic hyponatremia
