Interpretation of Lab Tests Flashcards
Lab Testing general principles
1-routine testing diff per facility (EKG and preg) 2-indicated testing based on patient disease states 3- timing of testing 60 considered “current”, w/ disease req closer to surgery
Hematology Testing: CBC+diff 1/2 WBC count
CBC/diff(measures diff type of leukocytes which aid in Dx, leukocytosis: appy, inflammation, dehydration vs leukopenia: bone marrow failure)
Hematology Testing: CBC+diff 2/2 RBC Count
RBC: M4.7-6.0, W4.2-5.4 -transport oxygen/CO2 inbetween tissues/lungs. “Anemia” decr by 10% of NL value: bone marrow failure, GIB, renal failure (no erythropoieten) / Erythrocytosis: dehydration, high altitude compensation, COPD compensation, congenital heart disease. Polycythemia vera = acquired disorder, uncontrolled RBCs production, incr viscosity
Indications for CBC/WBC
hemtologic disorder, vascular procedure, chemotherapy, unknown sickle cell status // leukemia/lymphoma, radiation/chemo, susp infection, aplastic anemia, hypersplenism, autoimmune disorder
Hematology Testing: Hgb
Main component of RBC. Threshold for non systemic disease patient 7g/dL.Higher threshold in systemic disease, CV disease, elderly, critical pts. M 13.5-17.5, W12-16.
Hemoglobin Characteristics
4 polypeptide chains, 2 alpha, 2 beta. Heme molecule in middle in Fe2+ state. Binding site for o2, up to 4 o2 molecules per Hgb. Elevated: COPD, CHF, dehydration, high altitudes. Decreased: anemia, hemorrhage, CRF. incr viscosity
Hematology Testing: Hct
“packed cell volume”. # of cells by %, remainder is plasma. Reflective of Hgb and RBC, Hct:Hgb = 3:1. M42-52%, W37-47%. Decreased: hemorrhage, anemia (<30 is mod-severe), leukemia, hemolytic rxn. Increased: dehydration, polycythemia, COPD, congenital heart disease.
Hematology Testing: Platelets
> 400,000 = cancer, polycythemia vera. <150,000
Indications for H&H
hematologic malignancy, recent radiation/chemo, renal disease, anticoag Rx, high EBL potential, systemic disorders
Coagulation Testing: PT (prothrombin time) (factor 2)
NL 10-14 secs, Protein made in liver, dependent on Vit K. Measures VitK dependent factors: 1,2,5,7,10. longer PT with deficient factors, monitors coumadin therapy (2-2.5 x nl). increased: liver disease, cirrhosis, hepatitis, biliary disease (limited bile for fat (vitk) metabolism.
Coagulation Testing: Ptt (activated partial thromboplastin time)
NL 25-32 secs. Monitors heparin therapy. Eval clotting factors: intrinsic path 8,9,11,12, common path1,2,5,10 Increased: liver disease, heparin therapy, hemphilia (fx 8=a, 9=b), VW disease. NO SPINAL/EPIDURAL WHILE ON HEPARIN THERAPY, must have normal aPtt.
Indications for Coag Test
leukemia, hepatis disease, bleeding disorder, anti coag threapy, severe malnutrition/absorption, baseline for post op anti coag therapy
Indications for Chemistry Test
renal disease, adrenal or thyroid disease, chemo, pituitary/hypothalamic disorder, body fluid loss/shifts (bowel prep, lasix), CNS disease
Calcium levels and fxn
Total 8.5-10.5, Ionized (non-protein bound-active form we care about, 50%) 4.4-5.4 mg/dL. Fxns: NM transmission, skeletal/cardiac contraction, coagulation, 2nd messenger H-mone release, membrane stability. Total serum levels dependent on albumin levels.
Causes // Tx of hypocalcemia
massive transfusion (citrated blood), hypervent (incr pH more pro-bound Ca), hypoPTH (no rls of Ca from bone), VitD insuff (decr GI calc absorption), CRF & hyperphospatemia (inverse to Ca) // Calc Gluc or Calc Chloride (more bio-available, burns inj) 10% over 10m, admin Vitd, monitor ECG
Causes // Tx of hypercalcemia
> 14mg/dL!! Bone dumping of calcium overloads capacity to excrete: Most commonly hyper PTH, malignancy. (acidosis shift to more active Ca) // NS infusion, loop diuretic, fix other lyte issues.
Signs and Symtpoms: Hypocalcemia
Increased nerve excitability: Paresthesia, confusion, laryngospasm, Trousseau(arm)/Chvosteks(face), Seizures, Prolong QT
Signs and Symptoms: Hypercalcemia
Depressed excitability: anorexia, n/v, polyuria, muscle weakness, imparied memory, lethargy/stupor, short QT & prolonged PR
Sodium levels and fxn (must assess balance of solute Na and solvent Water, what is the net gain loss of each comparitively)
135-148 meq/L, most abundant ECF ion. Fxn- maintain osmotic gradient, acid base balance, transmit nerve impulses. Reg by: aldosterone (renal retention), ANP (renal secretion), ADH (retain water, salt follows).
Causes // Tx hyponatremia
severe vomit/diarrhea, excessive free water intake/SIADH, ascites/peri edema, diuretics. Possibility of cerebral edema as sodium content determines vascular tonicity in brain. Tx: should eval serum osmo/urine Na to determine fluid excess:Na loss balance // fluid restriction, diuresis, poss 3% (symptomatic pts) saline 1-2 cc/kg/hr, goal of 1-2 meq/hr increase, then 10-15 mmol/24 hours.
Causes // Tx hypernatremia
dehydration & poor water intake, ID, Cushings syndrome (excess aldosterone). Tx: replacement of water deficit w/ hypotonic solutions (acute hyperNa), Isotonic solutions (chronic hyperNa) then hypotonic once euvolemic, slowed focused process similar to hypoNa tx.
Signs and Symptoms: Hyponatremia // hypernatremia
HypoNa: anorexia, n/v, cramps, weakness, confusion, agitation, Sz/coma // HyperNa: thirst, weakness, muscle twitching, irritability, disorientaiton, Sz/coma
Chloride measurement // Hypo/Hyper Causes: usually involved with metabolic derangement (r/t bicarb status)
NL 96-106. Ion follow Na, major ECF anion. Fxn: water balance, acid base balance. Hypo: vomit, gastric sxn, metabolic alkalosis (acid lost) & resp acidosis (comp) // Hyper: dehdration, metabolic acidosis (sub bicarb for Cl) and resp alkalosis (comp)
Potassium Levels and Fxn
NL 3.5-5meq/L. Major cation of ICF, K is excreted by kidneys w/o resoprtion. Imbalance creates disorder or RMP. Fxn: nerve conduction and muscle fxn, assist in controlling rate/force of cardiac contraction, helps with osmotic and acid base balances
