Chapter 4-Lab Values and Drug Monitoring Flashcards
Point of care testing
Provides rapid results at the site of patient care. There are many POC tests, including tests for cardiac enzymes, A1C, INR, and dvarious infections.
Complete Blood Count
Analyzes WBCs, RBCs, and PLTs
Hg and Hct
CBC with differential
the types of neutrophils are analyzed
Basic Metabolic Panel
Includes 7-8 tests that analyze electrolytes, glucose, renal function, and acid/base (with HCO2 or bicarbonate) status. Some labs calculate and report an anion gap along with the BMP.
Comprehensive Metabolic Panel (CMP)
Includes the tests of the BMP plus albumin, ALT, AST, total bilirubin, and total protein.
> ——<
…………..Hgb
WBC>———–<PLT
Hct
—-|——|—–<
Na |Cl |BUN
————————<Glucose
K |HCO3|SCr
Leukocytosis
Increased WBC
Polycythemia
Increased RBC
Thrombocytosis
Increased platelets
Leukopenia
Decreased WBC
Anemia
Decreased RBC or Hgb
Thrombocytopenia
Decreased platelets
Myelosuppression
Decreased WBCs, RBCs, and platelets
Agranulocytosis
Decreased granulocytes (WBCs that have secretory granules in the cytoplasm). Includes decreased neutrophils, basophils, and eosinophils
Drug causes of agranulocytosis
Clozapine, propylthiouracil, methimazole, procainamide, carbamazepine, sulfamethoxazole/trimethoprim, isoniazid
Granulocytes
Neutrophils, basophils, eosinophils
TJC requires that accredited facilities create and follow a protocol to
identify and report critical values to the responsible healthcare provider, who has an established timeframe to manage the result.
Calculate corrected calcium when
albumin is low.
Correction is not needed for ionized calcium
Increased calcium is due to
Calcium supplementation, vitamin D, thiazide diuretics
Decreased calcium is due to
Long-term heparin, loop diuretics, bisphosphonates, cinacalcet, systemic steroids, calcitonin, foscarnet, topiramate
When should you supplement calcium?
Pregnancy, osteoporosis/osteopenia and with certain drugs
Increased Mg is due to
Magnesium-containing antacids and laxatives (higher risk with renal impairment)
Decreased Mg is due to
PPIs, diuretics, amphotericin B, foscarnet, echinocandins, diarrhea, chronic alcohol intake
Phosphate is increased by
CKD
Phosphate is decreased by
phosphate binders, foscarnet, oral calcium intake
Potassium is increased by
ACE inhibitors, ARBs, aldosterone receptor antagonists, aliskiren, canagliflozen, cyclosporine, tacrolimus, mycophenolate, potassium supplements, sulfamethoxazole/trimethoprim, drospirenone containing oral contraceptives, chronic heparin use, NSAIDs, pentamidine.
Potassium is decreased by
beta 2 agonists, diuretics, insulin, steroids, conivaptan, mycophenolate
Sodium is increased by
hypertonic saline, tolvaptan. conivaptan
Sodium is decreased by
carbamazepine, oxcarbazepine, SSRIs, diuretics, desmopressin
Bicarbonate is increased by
loop diuretics, systemic steroids
Bicarbonate is decreased by
topiramate, zonisamide, salicylate overdose
BUN increased in
renal impairment and dehydration
BUN is used with
SCr to assess fluid status and renal function (BUN:SCr)
SCr is increased by
aminoglycosides, amphotericin B, cisplatin, colistimethate, cyclosporine, loop diuretics, polymyxin, NSAIDs, radiocontrast dye, tacrolimus, vancomycin
SCr can be falsely increased by
Sulfamethoxazole/trimethoprin, H2RAs, cobicistat
SCr is lowered by
low muscle mass, amputation, hemodilution
An increased anion gap suggests
metabolic acidosis
What are WBCs used to diagnose?
Used to diagnose/monitor infection and inflammation. Can increase as an acute phase reaction, indicating a systemic reaction to inflammation or stress (surgery)
WBCs are increased by
systemic steroids, colony stimulating factors, epinephrine
WBCs are decreased by
Clozapine, chemotherapy that targets bone marrow, carbamazepine, cephalosporins, immunosuppressants (DMARDs, biologics), procainamide, vancomycin
Neutrophils and bands are used
with clinical s/sx to assess the likelihood of acute infection. WBCs are used in the absolute neutrophils count calculation
Neutrophils are also called
Polymorphonuclear cells (PMNs or polys) or segmented neutrophils (segs)
bands
Immature neutrophils released from the bone marrow to fight infection (called a left shift when elevated)
Eosinophils increase in
drug allergy, asthma, inflammation, parasitic infection
Basophils increase in
Inflammation, hypersensitivity reactions, leukemia
Lymphocytes increase in
viral infections, lymphoma
Lymphocytes decrease in
bone marrow suppression, HIV, or due to systemic steroids
Monocytes increase in
chronic infections, inflammation, stress
RBCs lifespan
120 days
RBCs increase due to
ESAs, smoking, and polycythemia
RBCs decrease due to
Chemotherapy that targets the bone marrow, low production, blood loss, deficiency anemias, hemolytic anemias, sickle cell anemia
Hemoglobin is
The iron-containing protein that carries oxygen in RBCs
Hgb/Hct increases due to
ESAs
Hgb/Hct decreased in
anemias and bleeding
See Coombs test and G6PD for drug-induced anemias
Mean Corpuscular Volume (MCV)
Reflects the size and average volume of RBCs
MCV increases
Macrocytic anemia due to B12 or folate deficiency
MCV decreases
Microcytic anemia due to iron deficiency
Folic acid decreases by
phenytoin/fosphenytoin, phenobarbital, primidone, methotrexate, sulfamethoazole/trimethoprim, sulfasalazine
Supplement folic acid in
Women of childbearing age and alcoholism
Vitamin B12 decreases by
PPIs, metformin, colchicine, chloramphenicol
Reticulocyte count
Measures the amount of reticulocytes (immature red blood cells) being made by the bone marrow
Reticulocyte count is increased in
Blood loss
Reticulocyte count is decreased in
untreated anemia, due to iron, folate, or B12 deficiency, and with bone marrow suppression
Coombs test, direct
Used in the diagnosis of hemolytic anemia when the cause is unclear
Drugs that can cause hemolytic anemia
penicillins and cephalosporins, dapsone, isoniazid, levodopa, methyldopa, methylene blue, nitrofurantoin, pegloticase, primaquine, quinidine, quinine, rasburicase, rifampin, and sulfonamides
G6PD
Used to determine if hemolytic anemia is due to G6PD deficiency
RBC destruction with G6PD deficiency is triggered by
Stress, foods (fava beans)
Drugs- dapsone, methylene blue, nitrofurantoin, pegloticase, primaquine, rasburicase, sulfonamides
Therapeutic doses of LMWH anti Xa level
Obtain a peak anti-Xa level 4 hours after a SC LMWH dose: 1-2 IU/ml
Unfractionated heparin anti Xa level
Obtain 6 hours after IV infusion starts and every 6 hours until therapeutic: 0.3-0.7 IU/mL
Anti-Xa
Used to monitor low molecular weight heparins and unfractionated heparin. Monitoring for LMWH is recommended in preganancy and may be used in obesity, low body weight, pediatrics, elderly, renal insufficiency
PT/INR
Used to monitor warfarin
INR increases (without warfarin)
Due to liver disease
False increases in INR
daptomycin, oritavancin, telavancin
aPTT or PTT
Used to monitor UFH and direct thrombin inhibitors (argatroban)
False increases in aPTT or PTT
Oritavancin, telavancin
UFH when to obtain PTT/PTT
obtain 6 hours after IV infusion starts and every 6 hours until therapeutic
Platelets have an average lifespan of
7-10 days
Spotaneous bleeding can occur when platelets are
<20,000 cells/mm^3
PLTs decrease bt
heparin, LMWH, fondaparinux, glycoprotein IIb/IIIa receptor antagonists, linezolid, valproic acid, chemotherapy that targets bone marrow
Albumin decreases due to
Cirrhosis and malnutrition
What drugs are impacted by low albumin
Highly protein bound drugs
Warfarin, calcium, phenytoin
What drugs need correction for low albumin?
Phenytoin, valproic acid, and calcium
Bilirubin
Used along with other liver tests to determine causes of liver damage and detect bile duct blockage
Ammonia increases due to
Valproic acid, topiramate
Ammonia decreases due to
Lactulose
Amylase/Lipase
Pancreatic enzymes
Increase in pancreatitis, which can be caused by didanosine, stavudine, GLP-1 agonist, DPP4inhibitors, valproic acid, hypertriglyceridemia
CK or CPK
Use to assess muscle inflammation (myositis) or more serious muscle damage and to diagnose cardiac conditions
CK or CPK increases due to
Daptomycin, quinipristin/dalfopristin, statins, fibrates, emtricitabine, tenovir, tipranavir, raltegravir, dolutegravir
Markers of cardiac stress
BNP and NT-proBNP.
They are not HF or heart disease specific, but higher values indicate a higher likleihood of HF when consistent with HF symptoms
Myoglobin
Marker of muscle injury
How long should fasting occur before lipid blood draw?
9-12 hours before
LDL goal
<100 mg/dL
HDL goal
> /= 60 is goal
<40 is low
CRP
Indicates inflammation which could be due to many conditions (infection, trauma, malignancy).
Higher levels indicate increased risk.
High sensitivity CRP is more sensitive for CVD
Ankle brachial index
Measures the ratio of BP in the lower legs to the BP in the arms. Used to assess the severity of peripheral artery disease. An ABI <1 indicated some degree of PAD.
Fasting begins how long before FPG draw?
> /= 8 hours
What FPG is positive for diabetes?
> /= 126 mg/dL
What FPG is positive for prediabetes
100-125mg/dL
Hemoglobin A1C is based on
The attachment of glucose to hemoglobin.
Increased glucose= increased BG attached to Hgb= Increased A1C
Normal estimated average glucose
<154 mg/dL
An eAG of 126 corresponds to an A1C of
6%
Preprandial blood glucose goal
80-130 mg/dL
Postprandial blood glucose goal
<180mg/dL
C-Peptide
Insulin breakdown product used to evaluate beta cell function (distinguishes type 1 and 2 diabetes).
Decreased or absent in type 1 diabetes
Increased TSH=
Hypothyroidism
Decreased TSH=
Hyperthyroidism
TSH can be increased or decreased by
Amiodarone, interferons
TSH can be increased (hypothyroidism) due to
Tyrosine kinase inhibitors, lithium, carbamazepine
Uric acid increases due to
diuretics, niacin, low doses of aspirin, pyrazinamide, cyclosporine, tacrolimus, select pancreatic products, select chemotherapy (due to tumor lysis syndrome)
Nonspecific tests used in autoimmune disorders, inflammation, infections
CRP, Rheumatoid factor, erythrocyte sedimentation rate (ESR), antinuclear antibodies (ANA), antihistamine antibodies
Drug-induced lupus erythematosus (DILE)
Can be caused by many drugs. More likely with anti-TNF agents, hydralazine, isoniazid, methimazole, methyldopa, minocycline, procainamide, propylthiouracil, quinidine, terbinafine.
Causative agent must be D/Cd
CD4T immunocompromised state
<200 cells/mm^3
Arterial blood gas
Must be drawn from an artery
pH, pCO2, pO2, HCO3, O2 sat
Human Chorionic Gonadotropin (hCG)
Positive result indicates pregnancy
Luteinizing Hormone (LH)
Rises mid/cycle, causes egg release from the ovaries (ovulation)
Lactic acidosis indicates
Anaerobic metabolism, which occurs in long-distance running and in certain medical conditions (sepsis)
Lactic acid is increased by
NRTIs, metformin, alcohol, cyanide
Prolactin increased by
Haloperidol, risperidone, paliperidone, methyldopa
Prolactin decreased by
Bromocriptine
Rapid plasma reagin (RPR) or Venereal diseases research laboratory (VDLR)
Used to screen for syphilis
Thiopurine methyltransferase (TPMT)
Those with genetic deficiency of TPMT are at increased risk for myelosuppression and may require lower doses of azathioprine and mercaptopurine
Decreased vitamin increases risk of
Osteoporosis, osteomalacia (rickets), CVD, diabetes, hypertension, infectious diseases, and other diseases
Carbamazepine normal therapeutic range
4-12 mcg/mL
Digoxin normal therapeutic range
0.8-2 ng/mL (AF)
0.5-0.9 ng/mL (HF)
Gentamicin (traditional dosing) normal therapeutic range
Peak: 5-10 mcg/mL
Trough: <2 mcg/mL
Lithium normal therapeutic range
0.6-1.2 mEq/L
Phenytoin/Fosphenytoin normal therapeutic range
10-20 mcg/mL.
If albumin is low calculate corrected calcium
Free phenytoin normal therapeutic range
1-2.5mcg/mL
Procainamide normal therapeutic range
4-10 mcg/mL
NAPA normal therapeutic range
15-25 mcg/ml
Procainamide + NAPA combined normal therapeutic range
10-30 mcg/ml
Theophylline normal therapeutic range
5-15mcg/mL
Tobramycin normal therapeutic range
Peak: 5-10 mcg/ml
Trough <2 mcg/ml
Valproic acid normal therapeutic range
50-100 mcg/ml (up to 150 in some patients)
Vancomycin normal therapeutic range
Trough: 15-20 mcg/mL for most serious infections (pneumonia, endocarditis, osteomyelitis, meningitis, bacteremia)
Trough: 10-15 mcg/ml for others
Warfarin normal therapeutic range
Goal INR 2-3 for most conditions, use higher range (2.5-3.5) for high-risk conditions, such as mechanical mitral valves
