Labs Flashcards
What do the following labs order:
-Complete Blood Count (CBC)
-CBC with differential
CBC:
-White blood cells (WBCs) = leukocytes
-Red blood cells (RBCs) = erythrocytes
-Platelets (PLTs)
CBC w/ differential: CBC labs + types of WBCs ordered
What do the following labs order:
-Basic metabolic panel (BMP)
-Comprehensive metabolic panel (CMP)
BMP: electrolytes, glucose, renal function, and acid/base tests
-Some calculate anion gap
CMP: BMP labs + albumin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin, total protein
-Addition tests for liver function
Calcium (Ca++):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation of values/drugs that can cause imbalances
-When supplementation is indicated
Ranges:
-Ca, total: 8.5-10.5 mg/dL
-Ca, ionized: 4.5-5.1 mg/dL
Interpretation:
-FIRST: is albumin low? yes –> calculate corrected Ca++
-High Ca: could be Ca supplementation, vitamin D, or thiazide diuretics
-Low Ca: long-term HEPARIN, LOOP DIURETICS, BISPHOSPONATES, cinacalcet, systemic steroids, calcitonin, foscarnet, topiramate
Supplementation: in pregnancy, osteoporosis/osteopenia, certain medications
Magnesium (Mg):
-Common Reference Range (likely provided on NAPLEX)
-Drugs that can cause imbalances
-When supplementation is indicated
Range: 1.3-2.1 mEq/L
Drug-induced:
-High: magnesium-containing antacids and laxatives –> risk of renal impairment
-Low: PPIs, DIURETICS, AMPHOTERICIN B, foscarnet, echinocandins, diarrhea, chronic alcohol intake
Phosphate (PO4):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation of values/causes of imbalances
Range: 2.3-4.7 mg/dL
Interpretation:
-High: CHRONIC KIDNEY DISEASE
-Low: phosphate binders, foscarnet, oral Ca+ intake
Potassium (K+):
-Common Reference Range (likely provided on NAPLEX)
-Drug causes of imbalances
Range: 3.5-5 mEq/L
Drug-induced:
-RAAS Inhibitors: ACEIs, ARBs, aliskiren
-K+-sparing diuretics
-Others: CANAGLIFLOZIN, CYCOSPORINE, TACROLIMUS, K+-SPARING DIURETICS, K+ SUPPLEMENTS, SMX/TMP, DROSPIRENONE, oral contraceptives, chronic heparin use NSAIDs, pentamidine
Low levels: BETA-2 AGONISTS, DIURETICS (not-K sparing), INSULIN, SODIUM POLYSTYRENE SULFONATE, steroids, conivaptan
Mycophenolate: can increase and decrease K+
Sodium (Na):
-Common Reference Range (likely provided on NAPLEX)
-Drug causes of imbalances
Range: 135-145 mEq/L
Drug-induced:
-High: HYPERTONIC SALINE, TOLVAPTAN, conivaptan
-Low: CARBAMAZEPINE, OXCARBAZEPINE, SSRIs, DIURETICS, desmopressin
Bicarbonate (HCO3):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation/Drug causes of imbalances
Range:
-Venous: 24-30 mEq/L
-Arterial: 22-26 mEq/L
Interpretation: used to assess acid-balance status
Drug-induced:
-High: loop diuretics, systemic steroids
-Low: TOPIRAMATE, zonisamide, salicyclate overdose
Blood Urea Nitrogen (BUN):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: 7-20 mg/dL
Interpretation: used with SCr to assess fluid status and renal function - high levels/ratios between BUN:SCr suggests renal impairment and dehydration
Serum Creatinine (SCr):
-Common Reference Range (likely provided on NAPLEX)
-Drugs that increase SCr
-Drugs that falsely increase SCr
-Causes of low SCr
Range: 0.6-1.3 mg/dL
Drug-induced Increased SCr (KNOW ALL):
-Antimicrobials: aminoglycosides, Amphotericin B, polymixin, colistimethate, vancomycin
-Oncology, immune modulators: cyclosporine, tacrolimus, cisplatin
-Others: NSAIDs, loop diuretics, radiocontrast dye
False increased SCr: SMX/TMP, H2RAs, cobicistat
Low SCr: decreased muscle mass, amputation, hemodilution
Anion Gap (AG):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: 5-12 mEq/L
Interpretation: calculated value that when increased, suggests metabolic acidosis
White Blood Cells (WBCs):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
-Drug causes of imbalances
Range: 4,000-11,000 cells/mm3
Interpretation: used to diagnose/monitor infections or inflammation
-Increases can be acute phase reactant from stress (ex. surgery)
Drug-induced:
-High: SYSTEMIC STEROIDS, colony stimulating factors, epinephrine
-Low: CLOZAPINE, CARBAMAZEPINE, CHEMOTHERAPY, IMMUNOSUPPRESSANTS (DMARDs, biologics), cephalosporins, procainamide, vancomycin
Neutrophils (segmented and bands):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range:
-Neutrophils, segmented (polymorphonuculear segmented) 43-75%
-Bands (immature neutrophils): 3-5%
Interpretation: used to assess likelihood of acute infection
-Can be used with WBCs for absolute neutrophil count (ANC) calculation
-Bands specifically are released from bone marrow to fight infections (“left shift” when elevated)
Eosinophils:
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: 0-5%
Interpretation: increased during drug allergy, asthma, inflammation, and parasitic infections
Basophils:
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: 0-1%
Interpretation: increased from inflammation, HYPERSENSITIVITY RXNS, and leukemia
Lymphocytes:
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: 20-40%
Interpretation:
-High: viral infections, lymphoma
-Low: bone marrow suppression, HIV, systemic steroids
Red Blood Cells (RBCs):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range:
-Males: 4.5-5.5 x10^6 cells/uL
-Females: 4.1-4.9 x10^6 cells/uL
Interpretation:
-RBCs have an average lifespan of 120 days
-High: erythropoesis-stimulating agents (ESAs), smoking, polycythemia (condition that increases RBCs)
-Low: chemotherapy, low production, blood loss, deficiency anemia, hemolytic anemia, sickle cell anemia
Hemoglobin (Hgb, Hb):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range:
-Males: 13.5-19 g/dL
-Females: 12-16 g/dL
Interpretation: iron-containing protein that carries oxygen in RBCs
-High: erythropoesis-stimulating agents (ESAs)
-Low: anemias, bleeding, drug-induced (anticoagulatns, antiplatelets, anti-fibrinolytics)
Mean Corpuscular Volume (MCV):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: 80-100 fL
Interpretation: reflects size and average volume of RBCs
-High: macrocytic anemia due to B12 or folate deficiency
-Low: microcytic anemia due to iron deficiency
Folic Acid (folate):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
-Drugs that can cause high folate
-When to supplement folate
Range: 5-25 mcg/L
Interpretation: deficiency suggests macrocytic anemia
Drug-induced:
-High: PHENYTOIN (fosphenytoin), PHENOBARBITAL, PRIMIDONE, METHOTREXATE, SMX/TMP, sulfasalazine
Supplementation: consider in women of child-bearing age and alcohol use disorder
Vitamin B12:
-Common Reference Range (likely provided on NAPLEX)
-Drugs that can cause low B12
Range: >200 pg/mL
Drug-induced B12 deficiency: METFORMIN, PROTON PUMP INHIBITORS, colchicine, chloramphenicol
Reticulocyte Count:
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: 0.2-0.5%
Interpretation: the amount of reticulocytes (immature RBCs) made by bone marrow
-High: blood loss, hemolysis
-Low: untreated anemia (iron, folate, or B12 deficiency), bone marrow suppression
Coombs Test, Direct (“Direct Antiglobulin Test = DAT”)
-Test is used for the diagnosis of _____________
-What are drugs that can cause this?
Positive: immune-mediated hemolytic anemia
Drug-induced: penicillins, cephalosporins, isoniazid, levodopa, methyldopa, quinidine, quinine, rifampin, sulfonamides
Glucose-6-Phosphate Dehydrogenase (G6PD):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: 5-14 units/g
Interpretation: RBC destruction can be triggered with deficiency caused by stress, food (fava beans), or drugs (dapsone, methylene blue, nitrofurantoin, pegloticase, primaquine, rasburicase, quinidine, quinine, and sulfonamides)
Anti-Factor Xa Activity (Anti-Xa):
-Activity should be monitored _____ hours after administration of low molecular weight heparin (LMWH) is given as peak dose, and ______ hours after heparin.
-What are the typical ranges?
-Who is specifically indicated for LMWH monitoring?
Range:
-LMWH: monitor 4 hours afters; range: 1.0-2.0 IU/mL
-Heparin: monitor 6 hours after; range: 0.3-0.7 IU/mL
LMWH Monitoring: pregnancy
-May be used in obesity, low body weight, pediatrics, elderly, renal insufficiency
Prothrombin Time (PT) / International Normalized Ratio (INR)
-Common Reference Range (likely provided on NAPLEX)
-Purpose of INR
-What disease state increases INR?
-What drugs falsely evelate INR?
Range:
-PT: 10-13 seconds (can vary)
-INR: <1.2 (if NOT on warfarin)
Purpose: used to monitor warfarin
-Increased INR (w/o being on warfarin): liver disease
-False increased INR from drugs: daptomycin, ortivancin, televancin
Activated Partial Thromboplastin Time (aPTT or PTT):
-Common Reference Range (likely provided on NAPLEX)
-Monitor ______ hours after administering heparin. What is the goal when on heparin?
-What drugs can cause false increases in aPTT?
Range: 22-38 seconds (can
Unfractionated heparin (UFH): take 6 hours after infusion starts and Q6 hours until therapeutic - goal is to be 1.5-2.5x the control
False increases: ortivancin, telavancin
Platelets (PLTs):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
-Drugs that lower PLTs
Range: 150,000-450,000 cells/mm3
Interpretation: PLTs have average lifespan of 7-10 days, and spontaneous bleeding can occur when <20,000 cells/mm3
Drugs that lower PLTs: HEPARIN, LMWHs, FONDAPARINUX, LINEZOLID, VALPROIC ACID, glycoprotein IIb/IIIa receptor antagonists, chemotherapy
Albumin:
-Common Reference Range (likely provided on NAPLEX)
-What can cause low albumin?
-What highly protein-bound drugs will be affected by low albumin?
Range: 3.5-5 g/dL
Low albumin: cirrhosis, malnutrition
Highly-protein bound drugs: warfarin, calcium, phenytoin
-Phenytoin and serum calcium levels require correction for low albumin
Aspartate Aminotransferase (AST) / Alanine Aminotransferase (ALT):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range:
-AST: 10-40 units/L
-ALT: 10-40 units/L
Interpretation: enzymes that are released from injured hepatocytes
Billirubin, total (Tbili):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: 0.1-1.2 mg/dL
Interpretation: used along with other liver tests to determine causes of liver damage and detect bile duct blockage
Amylase and Lipase:
-Common Reference Range (likely provided on NAPLEX)
-Interpretation/drug causes
Range:
-Amylase: 60-180 units/L
-Lipase: 5-160 units/L
Interpretation: increased in pancreatitis, which can be caused by didanosine, stavudine, GLP-1 agonists, DPP-4 inhibitors, valproid acid, hypertriglyceridemia
Creatine Kinase (CK) / Creatine Phosphokinase (CPK):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
-What drugs increase these levels
Range:
-Males: 55-170 IU/L
-Females: 5-160 IU/L
Interpretation: used to assess muscle inflammation (myositis) or more serious muscle damage; for diagnosis of cardiac conditions
Increased from: DAPTOMYCIN, STATINS, TENOFOVIR, RALTEGRAVIR, DOLUTEGRAVIR, emtricitabine, fibrates (especially when given w/ statin), tipranavir
Cardiovascular Markers: Explain what each of the following indicates if elevated:
-CK-MB Isoenzymes
-Troponin T (TnT)
-Troponin I (TnI)
-B-Type Natriuretic Peptide (BNP)
-N-Terminal-ProBNP (NT-proBNP)
CK-MB, TnT, TnI: diagnosis of MI
-Troponins can be elevated in sepsis, PE, or CKD
BNP and NT-proBNP: markers of cardiac stress with likelihood of HF when consistent WITH SYMPTOMS
-Second common reason for elevation is renal failure
Myoglobin and CK-MB are NOT interchangeable
-Myoglobin: sensitive marker for muscle injury, but relatively low specificity for acute MI
Lipid Panel: Typical values for for
-Total Cholesterol (TC)
-High Density Lipoprotein (HDL)
-Low Density Lipoprotein (LDL)
-Trigylcerides (TG)
Fasting should occur ____-____ hours before blood draw
TC: <200mg/dL
HDL: ideally >/= 60 mg/dL (men low: <40; women low <50)
LDL: <100mg/dL (hx of ASCVD: <70 mg/dL)
TG: <150 mg/dL (>500: increased risk for pancreatitis)
Fasting: 9-12 hours before blood draw
C-reactive protein (CRP):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: 0-0.5 mg/dL
Interpretation: increased levels indicate inflammation (infection, trauma, malginancy)
-High-sensitivity CRP (hs-CRP) more sensitive for CVD
Fasting Plasma Glucose (FPG):
-Common Reference Range (likely provided on NAPLEX)
-Fasting should occur at least ____ hours before blood draw
Range:
-Prediabetes: 100-125mg/dL
-Diabetes: >/=126 mg/dL
Fasting: at least 8 hours before blood draw
Hemoglobin A1c (A1c):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range:
-ADA: <7%
-AACE: </= 6.5%
Interpretation: average blood glucose over past 3 months
-Increased glucose, increases attachment to Hgb, increasing A1c
C-Peptide (fasting):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: 0.78-1.89 ng/mL
Interpretation: insulin breakdown product used to evaluate beta-cell function (distinguishes T1DM from T2DM)
-Decreased or absent in T1DM
Urinary Albumin Excretion (UAE):
-Common Reference Range (likely provided on NAPLEX)
Range: <30 mg/24 hours
Thyroid Stimulating Hormone (TSH):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
-Drugs that can change TSH levels
Range: 0.3-3 mIU/L
Interpretation: used with T4 to diagnose hypo- or hyperthyroidism and monitoring
-High TSH = hypothyroidism (TSH produced in higher amounts to signal to thyroid to make hormones)
-Low TSH = hyperthyroidism (TSH produced in lower amounts for less thyroid production)
Drugs:
-Decreased TSH: amiodarone, interferons
-Increased TSH: amiodarone, inteferons, tyrosine kinase inhibitors, lithium, carbamazepine
Uric Acid:
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
-Drugs that increase uric acid
Range:
-Male: 3.5-7.2mg/dL
-Females: 2-6.5mg/dL
Interpretation: used in diagnosis/TX of gout
Drugs that increase uric acid: diuretics, niacin, low doses of ASA, pyrazinamide, cyclosporine, select pancreatic enzyme products, select chemotherapy from tumor lysis syndrome
Inflammation / Autoimmune Disease Markers: Explain the interpretation of the following
-C-Reactive Protein (CRP)
-Rheumatoid Factor (RF)
-Erythrocyte Sedimentation Rate (ESR)
-Antinuclear Antibodies (ANA)
ALL are NON-specific tests
CRP: high risk >3 mg/dL (normal: 0-0.5mg/dL)
RF: usually negative or less than upper limit, usually <20 IU/mL
ESR:
-Males: </= 20 mm/hr
-Females: </=30 mm/hr
ANA: if positive, an anti-dsDNA helps establish a diagnosis of systemic lupus erythematosus
-Drug-induced lupus erthematosus (DILE): anti-TNF agents, hydralazine, isonazid, methimazole, methyldopa, minocycline, procainamide, propylthiouracil, quinidine, terbinafine
HIV Measures: Explain the interpretation of the following:
-CD4 T Lymphocyte Count
-HIV RNA Concentration (“Viral Load”)
Used to diagnose HIV and monitor TX
-CD4 count used to indicate immune function and establish need for opportunistic infection prophylaxis
Prostate-Specific Antigen (PSA):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: <4 ng/mL
Interpretation: can be used to detect BPH and prostate cancer
-Increased with testosterone supplementation
Human Chorionic Gonadotropin (hCG):
-Interpretation
Interpretation: positive result from blood or urine indicates preganancy
Luteinizing Hormone (LH):
-Interpretation
Interpretation: rises mid-cycle, causing an egg to release from the ovaries (ovulation)
Lactic Acid (Lactate):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
-Drugs that can increase lactate
Range: 0.5-2.2 mEq/L
Interpretation: lactic acidosis indicates anaerobic metabolism, which occurs in long-distance running or certain medical conditions (ex. sepsis)
Drugs that increase: NRTIs, metformin (low risk mostly with renal disease and HF), alcohol, cyanide
Purified Protein Derivative (PPD) or Tuberculin Skin Test (TST):
-Test results for negative
-Interpretation
Negative result: no induration (raised area)
Interpretation: induration indicates Mycobacterium tuberculosis (latent TB)
Interferon-Gamma Release Assay (IGRA):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: negative
Interpretation: non-treponemal antibody test to screen for syphilis
-If these results are positive, test for treponemal assay to confirm
Thiopurine Methyltransferase (TPMT):
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: >/= 15 units/mL
Interpretation: genetic deficiency increases risk for myleosuppression potentially requiring lower doses for azathioprine and mercaptopurine
25-(OH)-Vitamin D:
-Common Reference Range (likely provided on NAPLEX)
-Interpretation
Range: >30 ng/mL
Interpretation: decreased levels increase risk of osteoporosis, osteomalacia (rickets), CVD, DM, HTN, infectious diseases, and other conditions
Usual therapeutic range of: Carbamazepine
4-12 mcg/mL
Usual therapeutic range of: Digoxin
Afib: 0.8-2 ng/mL
HF: 0.5-0.9 ng/mL
Usual therapeutic range of: Gentamicin (traditional dosing)
Peak: 5-10 mcg/mL
Trough: <2 mcg/mL
Usual therapeutic range of: Lithium
Trough: 0.6-1.2 mEq/L (up to 1.5 mEq/L for acute symptoms)
Usual therapeutic range of:
-Phenytoin / fosphenytoin
-Free Phenytoin
Phenytoin / Fosphenytoin: 10-20 mcg/mL (consider if albumin is low and adjust)
Free Phenytoin: 1-2 mcg/mL
Usual therapeutic range of:
-Procainamide
-NAPA (Procainamide active metabolite)
-Combined
Procainamide: 4-10 mcg/mL
NAPA: 15-25 mcg/mL
Combined: 10-30 mcg/mL
Usual therapeutic range of: Theophylline
5-15 mcg/mL
Usual therapeutic range of: Tobramycin (traditional dosing)
Peak: 5-10 mcg/mL
Trough: <2 mcg/mL
Usual therapeutic range of: Valproic acid
50-100 mcg/mL
Usual therapeutic range of: Vancomycin
Serious infections: AUC/MIC ratio of 400-600 recommended (associated w/ improved outcomes and less toxicity)
-Alternatively, trough: 15-20 mcg/mL
Other infections, trough: 10-15 mcg/mL
Usual therapeutic range of: Warfarin (INR)
Goal INR: 2-3
-2.5-3.5 if higher risk condition
