Chapter 4 - Lab Values & Drug Monitoring Flashcards
COMPLETE BLOOD CELL COUNT
- Consists of what?
- What is CBC with differential?
- RBCs average life span:
- Platelets average life span:
CBC:
- WBCs
- Neutrophils
- RBCs
- PLTs
- Hemoglobin (oxygen-carrying protein in RBCs)
- Hematocrit (the level of RBCs in the fluid component of the blood, or plasma).
CBC with differential:
- types of neutrophils are analyzed
RBCs average life span: 120 days
Platelets average life span: 7 -10 days
What are the BASIC METABOLIC PANEL (BMP) & COMPREHENSIVE METABOLIC PANEL (CMP)
- BMP: Electrolytes, glucose, renal function and acid/base (with the HC03, or bicarbonate).
- CMP: BMP + albumin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin and total protein.
– The additional tests are used primarily to assess liver function.
WBC > HGB/HCT< PLTS
Na / Cl / BUN
——————— < Glucose
K /HCO3/ SrCr
BLOOD CELL LINES:
- Stem cells in the bone marrow produce:
- Red blood cells (erythrocytes)
- White blood cells (leukocytes)
- Platelets
– Immature red blood cell: Reticulocyte
inc WBC is called:
Leukocytosis
inc RBC is called:
Polycythemia
inc platelet
Thrombocytosis
dec WBC
Leukopenia
dec RBC
Anemia
dec Platelet
Thrombocytopenia
Myelosuppression is when there’s a:
Decrease in:
- WBC
- RBC
- Platelets
Agranulocytosis
- Drug causes
- dec in what?
Drug causes:
- clozapine (BDZ - Sedative drug used to treat schizophrenia)
- propylthiouracil (Treats hyperthyroidism)
- methimazole (Treats hyperthyroidism)
- procainamide (Antiarrythmic)
- carbamazepine (BDZ - anticonvulsant/ analgesic)
- sulfamethoxazole/ trimethoprim
- isoniazid (Bacteriostatic - treats tuberculosis)
– Dec granulocytes (WBCs that have secretory granules in the cytoplasm);
– includes dec neutrophils, basophils and eosinophils
Calcium, total
- When do you calculate corrected calcium?
- When is it increased?
- When is it Decreased?
- When should u supplement with calcium?
- Calculate corrected calcium if albumin is low.
– Correction is not needed for ionized calcium. - Inc due to calcium supplementation, vitamin D, thiazide diuretics.
- Dec due to long-term heparin, loop diuretics, bisphosphonates, cinacalcet, systemic steroids, calcitonin, foscarnet, topiramate.
- Supplement calcium in pregnancy, osteoporosis/ osteopenia and with certain drugs.
Magnesium (Mg)
- When does it inc?
- When does it dec?
- BMP and Electrolytes
- Inc due to magnesium-containing antacids and laxatives with renal impairment.
- Dec due to PPls, diuretics, amphotericin B, foscarnet, echinocandins, diarrhea, chronic alcohol intake.
Phosphate (PO4)
- BMP and Electrolytes
- Inc in renal failure.
- Dec due to phosphate binders, foscarnet, oral calcium intake.
Potassium (K)
- BMP and Electrolytes
- Inc due to ACE inhibitors, ARBs, aldosterone receptor antagonists (ARAs), aliskiren, canagliflozin, cyclosporine, tacrolimus, mycophenolate, potassium supplements, sulfamethoxazole/trimethoprim, drospirenone- containing oral contraceptives, chronic heparin use, NSAIDs, pentamidine
- Dec due to beta-2 agonists, diuretics, insulin, steroids, conivaptan, mycophenolate (both inc and dec reported)
Sodium (Na)
- BMP and Electrolytes
- Inc due to hypertonic saline, tolvaptan, conivaptan.
- Dec due to carbamazepine, oxcarbazepine, SSRls, diuretics, desmopressin.
Bicarbonate
(HC03 or “bicarb”)
- BMP and Electrolytes
- Used to assess acid-base status
- Inc due to loop diuretics, systemic steroids.
- Dec due to topiramate, zonisamide, salicylate overdose.
Blood Urea Nitrogen (BUN)
- BMP and Electrolytes
- Inc in renal impairment and dehydration.
- Used with SCr (BUN:SCr ratio) to assess fluid status and renal function.
SerumCreatinine (SCr)
- BMP and Electrolytes
- Inc due to many drugs that impair renal function (aminoglycosides, amphotericin B, cisplatin, colistimethate, cyclosporine, loop diuretics, polymyxin, NSAIDs, radiocontrast dye tacrolimus, vancomicin).
- False inc due to sulfamethoxazole/trimethoprim, H2RAs, cobicistat.
- Dec with low muscle mass, amputation, hemodilution.
Anion Gap (AG)
- BMP and Electrolytes
- A calculated value, but often reported on the BMP.
- Presence of inc anion gap suggests metabolic acidosis.
White Blood Cells
- WBC and Differential
- Used to diagnose and monitor infection/inflammation
- Can inc as an acute phase reactant, indicating a systemic reaction to inflammation or stress
(surgery) - Inc due to systemic steroids, colony stimulating factors, epinephrine.
- Dec due to clozapine, chemotherapy that targets the bone marrow, carbamazepine, cephalosporins, immunosuppressants (OMAROs, biologics), procainamide, vancomycin.
Neutrophils & Bands
- WBC and Differential
- Neutrophils and bands are used with clinical s/sx to assess likelihood of acute infection and with WBC in absolute neutrophil count (ANC) calculation
- Neutrophils are also called polymorphonuclear cells (PMNs or polys) and segmented neutrophils (segs).
- Bands are immature neutrophils released from bone marrow to fight infection (called a “Left shift” when elevated).
Eosinophils
- WBC and Differential
- Inc in drug allergy, asthma, inflammation, parasitic infection.
Basophils
- WBC and Differential
- Inc in inflammation, hypersensitivity reaction, leukemia.
Lymphocytes
- WBC and Differential
- Inc in viral infections, lymphoma.
- Dec in bone marrow suppression, HIV or due to systemic steroids.
Anemia:
Red Blood Cells (RBC)
- Inc due to erythropoiesis-stimulating agents (ESAs), smoking and * polycythemia (a condition that causes high RBCs).
- Dec due to chemotherapy that targets the bone marrow, low production, blood loss, deficiency anemias (B12, folate), hemolytic anemia, sickle cell anemia.
Anemia: Hemoglobin
- Hgb is the iron-containing protein that carries oxygen in the RBCs.
- The Hct mirrors the Hgb result (providing the same clinical information}.
- Inc due to ESAs
- Dec in anemias and bleeding (risk with anticoagulants, antiplatelets, ibrinolytics).
Mean Corpuscular Volume (MCV)
- Inc due to B12 or folate deficiency.
- Dec due to iron deficiency.
Folic acid (folate)
B12 and folate are ordered for further workup of macrocytic anemia.
- Dec due to phenytoin/fosphenytoin, phenobarbital, primidone, methotrexate, sulfamethoxazole/ trimethoerim, sulfasalazine.
- Supplement folate in women of childbearing age and alcoholism
Vitamin B12
- Dec due to PPls, metformin, colchicine, chloramphenicol.
Methylmalonate
- Used for further workup of macrocytic anemia when B12 deficiency is suspected.
- Schilling test has also been used.
Reticulocyte count
- Measures the amount of reticulocytes (immature red blood cells) being made by the bone marrow; reticulocyte count is inc in blood loss and dec in untreated anemia due to iron, folate or B12 deficiency and with bone marrow suppression.
CoombsTest, Direct
- Used in the diagnosis of hemolytic anemia, when the cause of hemolysis is unclear (an immune mechanism vs. another cause).
- Drugs that can cause hemolytic anemia include penicillins and cephalosporins (prolonged use/high concentrations), dapsone, isoniazid, levodopa, methyldopa, methylene blue, nitrofurantoin, pegloticase, primaquine, quinidine, quinine, rasburicase, rifampin and sulfonamides.
- If the Coombs test is positive and a drug-induced cause is suspected, discontinue the offending drug.
Glucose-6-phosphate dehydrogenase
(G6PD)
- Used to determine if hemolytic anemia is due to G6PD deficiency (the result will be low).
- The RBC destruction with G6PD deficiency is triggered by stress, foods (fava beans) or these drugs: dapsone, methylene blue, nitrofurantoin, pegloticase, primaquine, rasburicase, sulfonamides
Anticoags: Antifactor XaActivity (Anti-Xa)
- Obtain a peak anti-Xa 4 hours after SC LMWH dose for proper interpretation
- Used to monitor low molecular weight heparins (LMWHs) and unfractionated heparin (UFH).
Monitoring for LMWH is recommended in pregnancy and possibly in obesity, low body weight, pediatrics, elderly, renal insufficiency. - Inc due to heparin, LMWHs, fondaparinux.
Anticoags: ProthrombinTime/ International Normalized
Ratio (PT/ INR)
Used to monitor warfarin. INR i (without warfarin) due to liver disease.
- False inc from daptomycin, oritavancin, telavancin.
Many drugs inc or dec INR
Anticoags: Activated Partial Thromboplastin Time
(aPTTor PTT)
- Used to monitor unfractionated heparin (UFH) and direct thrombin inhibitors (argatroban).
- False inc from oritavancin, telavancin.
Anticoags: Platelets (PLTs)
- Platelets are required for clot formation. Spontaneous bleeding can occur when platelets are < 20,000/mm 3.
- Dec due to heparin, LMWHs, fondaparinux, glycoprotein lib/Illa receptor antagonists, linezolid, valproic acid, chemotherapy that targets the bone marrow, rarely other drugs.
Liver and Gastroenterology: Albumin
- Dec due to cirrhosis and malnutrition.
- Serum levels of highly protein-bound drugs (warfarin, calcium, phenytoin) are impacted by low albumin.
- Phenytoin, valproic acid and calcium serum concentrations require correction for low albumin
- A “free” drug level does not require adjustment.
Liver and Gastroenterology:
- Aspartate Aminotransferase (AST)
- Alanine Aminotransferas (ALT)
AST and ALT are enzymes released from injured hepatocytes (liver cells).
Liver and Gastroenterology: Bilirubin
Used along with other liver tests to monitor drug toxicity, determine other causes of liver damage and detect bile duct blockage.
Pancreatic Enzymes:
- Amylase
- Lipase
- Inc in pancreatitis, which can be caused by:
– didanosine
– GLP-1 agonists
– DPP-4 inhibitors
– valproic acid
– hypertriglyceridemia
CV: Creatine Kinase or Creatine Phosphokinase
(CK or CPK)
- To assess muscle inflammation (myositis) or more serious muscle damage
- To diagnose cardiac conditions
- Inc due to daptomycin, quinupristin/dalfopristin, statins, fibrates (especially if given with a statin), emtricitabine, tenofovir, tipranavir, raltegravir, dolutegravir.
CV:
- TroponinT (TnT)
- Troponin I (TnI)
- B Type Natriuretic Peptide
- N-Terminal-ProBNP (NT-proBNP)
- As a group, these are called “cardiac enzymes.”
CK-MB, TnTand Tnl are used in the diagnosis of Ml. - Troponins can be elevated with a few other conditions (Sepsis, PE,CKD).
- BNP and NT-proBNP are both markers of cardiac stress.
- They are not heart failure (HF) nor heart disease-specific, but higher values indicate a higher likelihood of HF when consistent with HF symptoms.
- Renal failure is the second most common cause of inc BNP and NT-proBNP.
- Myoglobin and CK-MB are not interchangeable; they are two separate markers.
- Myoglobin is a sensitive marker for muscle injury but has relatively low specificity for acute Ml and therefore is not routinely used for diagnosis
Lipids and Cardiovascular Risk:
- Total Cholesterol Nl levels
< 200 mg/dl
Lipids and Cardiovascular Risk:
- Low Density Lipoprotein (LDL)
< 100 mg/dl, desirable
Lipids and Cardiovascular Risk:
High Density Lipoprotein (HDL)
> = 60 mg/dl, desirable
Non-HDL
< 130 mg/dl, desirable
Triglycerides
(TG)
< 150 mg/dl
Lipids and Cardiovascular Risk
- Lipid panel: TC, HDL, LDL, TG
- Fasting begins 9-12 hours prior to lipid blood draw
- Non-HDL = TC - HDL.
- Guidelines do not support specific TC, HDL or TG goals; they support a statin intensity level for LDL-C reductions based on those most likely to benefit
- This means that the target values are not being used as goals for treatment, but elevations should be recognized,
- In some individuals, additional treatment is considered if LDL >= 70mg/dl.
C-reactive Protein (CRP)
- Inc CRP indicates inflammation, which could be due to many conditions (infection, trauma, malignancy).
- Higher levels indicate inc risk.
- High- sensitivity CRP (hs-CRP) is more sensitive for CVD.
Fasting plasma glucose
- > = 126 mg/dl is positive for diabetes
- 100 - 125 mg/dl is positive for pre-diabetes
- > = 8 hrs fasting
Hemoglobin A1C
- < 7% (ADA)
- <= 6.5% (AACE)
- Average blood glucose over the past 3 months; based on attachment of glucose to hemoglobin; inc glucose = inc BG attached to Hgb = inc AlC.
Estimated Average Glucose
- < 154 mg/dl (ADA)
- Used to correlate a finger stick glucose with an A1C; an eAG of 126 mg/dl corresponds to an A1C of 6%.
Preprandial blood glucose
80-130 mg/dl (ADA)
Blood glucose measurement taken before a meal.
Postprandial blood glucose
- < 180 mg/dl (ADA)
- Blood glucose measurement taken after a meal (1-2 hours after the start of eating
C-peptide (fasting)
- Insulin breakdown product used to evaluate beta-cell function (distinguish type 1 from type 2 diabetes).
- Dec or absent in type 1 diabetes.
Thyroid Function: ThyroidStimulating Hormone
(TSH)
- TSH is used with FT4 to diagnose hypothyroidism and is used alone (sometimes with FT4) to monitor patients being treated.
- Inc TSH: hypothyroidism
- Dec TSH=hyperthyroidism
- Inc or dec due to amiodarone, interferons.
- Inc (hypothyroidism) due to tyrosine kinase inhibitors, lithium, carbamazepine.
Uric acid
- Used in diagnosis/treatment of gout.
- Inc due to diuretics, niacin, low doses of aspirin, pyrazinamide, cyclosporine, tacrolimus, select pancreatic enzyme products, select chemotherapy (tumor lysis syndrome).
Inflammation/ autoimmune disease
- C-Reactive Protein (CRP)
- Rheumatoid Factor, serum
- Erythrocyte Sedimentation Rate (ESR)
- Antinuclear Antibodies (ANA)
- Nonspecific tests used in autoimmune disorders, inflammation, infections.
- If ANA is positive, histone antibody and anti-dsDNA tests will help establish diagnosis.
- Drug-induced lupus erythematosus (DILE) can be caused by many drugs. More likely with anti-TN Fagents, hydralazine, isoniazid, methimazole, methyldopa, minocycline, procainamide, propylthiouracil, quinidine, terbinafine. The causative drug must be discontinued
HIV
- CD4+TLymphocyteCount
- HIV RNA Concentration (Viral Load)
- Used to assess HIV and monitor treatment
Acid-Base (Arterial Sample): pH
- Together these values make up an arterial blood gas (ABG). This blood must be drawn from an artery (not a vein, as with other labs).
- Often written in chart notes with a stick diagram: pH/pCO2/pO2/HCO3/ 02 Sat.
- Bicarbonate on the ABG is a calculated value, and reference range may differ from venous samples.
Prostate-Specific Antigen (PSA)
- Can inc with testosterone supplementation.
- Used in detecting prostate cancer and BPH.
Human Chorionic Gonadotropin
(hCG)
- Tested in blood or urine to determine pregnancy.
- A positive value in a female indicates she is pregnant.
Luteinizing Hormone (LH)
- Rises mid-cycle, causing egg release from the ovaries (ovulation).
- Tested in urine with ovulation predictor kits for women attempting pregnancy.
Lactic acid (lactate)
- Lactic acidosis indicates anaerobic metabolism, which occurs in long- distance running and in certain medical conditions (e.g.,sepsis).
- Inc due to NRTls (HIV), metformin (low risk/mostly with renal disease and heart failure), alcohol, cyanide.
Purified Protein Derivative or Mantoux test
(PPD)
TB skin test (TST
Rapid Plasma Reagin (RPR)
Antibody test used to screen for syphilis.
Thiopurine Methyltransferase
(TPMT)
Those with genetic deficiency of TPMT are at inc risk for myelosuppression (bone marrow suppression) and may require lower doses with azathioprine and mercaptopurine.
Vitamin D, serum 25(0H)
Dec levels increase risk of osteoporosis, osteomalacia (rickets), CVD, diabetes, hypertension, infectious diseases and other conditions.
peak and trough levels?
- The peak level is the highest concentration in the blood the drug will reach and requires time for the drug to distribute in the body’s tissues.
- The trough level is the lowest concentration the drug will reach in the blood and is drawn right before the next dose or some short period of time before the next dose (30 minutes is common).
When should you obtain drug levels?
Obtaining drug levels at steady state is often (but not always) preferred.
What are Narrow therapeutic index (NTI) drugs
- have a narrow separation between the subtherapeutic (low}, therapeutic (desired} and supratherapeutic (high) drug levels.
- Supratherapeutic drug levels can be toxic.
Carbamazepine usual therapeutic range
4-12 mcg/ml
Digoxin TDL
0.8-2 ng/ml (AFib)
0.5-0.9 ng/ml (HF)
Gentamicin (traditional dosing) TDL
Peak: 5-10 mcg/ml
Trough: < 2 mcg/ml
Lithium TDL
0.6-1.2 mEq/L {up to 1.5 mEq/L for acute symptoms), drawn as a trough
Phenytoin/Fosphenytoin
10-20 mcg/ml; if albumin is low, correct serum level;
FreePhenytoin
1-2.5 mcg/ml
Procainamide
4-10 mcg/ml
NAPA {procainamide active metabolite TDL
15-25 mcg/mL
Procainamide and NAPA Combined TDL
10-30 mcg/mL
Theophylline TDL
5-15 mcg/mL
Tobramycin (traditional dosing) TDL
Peak: 5-10 mcg/mL
Trough: < 2 mcg/mL
Valproic acid
50-100 mcg/mL {up to 150 mcg/mL in some patients); if albumin is low, correct serum level;
Vancomycin TDL
- Trough: 15-20 mcg/mL for most serious infections (pneumonia, endocarditis, osteomyelitis, meningitis, and bacteremia)
- Trough: 10-15 mcg/mL for others
Warfarin TDL
Goal INR is 2-3 for most indications, use higher range (2.5-3.5) for high-risk indications, such as mechanical mitral valves
