Lab values and Drug monitoring

Fishbone diagrams

Define Leukocytosis

High WBC

Define Leukopenia

low WBC

Define Thrombocytosis

high platelets

Define thrombocytopenia

low platelets

Define polycythemia

high red blood cells

Define anemia

low red blood cells

Define myelosuppression

Bone marrow suppression (decrease WBC, RBC, PLT)

What is agranulocytosis?

Decrease in granulocytes (neutrophils, basophils, eosinophils).

What medications can cause agranulocytosis?

Think in 3 clusters:

1. Antipsychotic → Clozapine (the famous one that requires mandatory REMS monitoring)

2. Antithyroid duo → Propylthiouracil + Methimazole

3. The rest → Procainamide, Carbamazepine, Isoniazid, Bactrim

Just remember: “Clozapine + the two thyroid drugs + Procainamide, Carbamazepine, INH, Bactrim”

What can affect Calcium levels?

Levels can be increased via: thiazide diuretics, Vitamin D and calcium supplementation

Levels can be decreased via: heparin, loop diuretics, Cinacalcet, oral bisphosphonates

When do we correct Calcium and what is the formula

We correct it when Albumin is low; correction is not needed for ionized Calcium

Corrected Ca = Ca + 0.8(4 - albumin).

What can cause Mg levels to be low?

Mnemonic: PAD

• PPIs

• Amphotericin B

• Diuretics

Just think: “PAD” = low Mag (like a soft, low pad).

What can lead to high phosphate levels?

CKD

What can effect Potassium levels?

Increased via:

• K – Potassium-sparing diuretics

• B – Bactrim and non-selective beta-blockers

• A – ACE inhibitors, ARBs, and ARNI

• N – NSAIDs

• K – Potassium supplements and salt substitutes

• S – SGLT2 inhibitors; canagliflozin

• D – Drospirenone

• T – Tacrolimus and cyclosporine

• H – Heparin and LMWHs

Decreased via: beta 2 agonists, insulin, SPS

What can effect Sodium levels

Increased: hypertonic saline

Decreased: SCAT

• SSRIs

• Carbamazepine & Oxcarbzepine

• ADH analogs(Desmopressin)

• Thiazide diuretics

What can effect Bicarbonate (HCO3) levels?

Increased via: loop diuretics, steroids.

Decrease: topiramate, zonisamide, salicylate overdose

What indicated dehydration?

BUN:SCr > 20:1

What can increase Serum creatinine (SCr)?

meds that impair renal function(nephrotoxic): LANCr

• Loop Diuretics

• Anti-infectives

• NSAIDs

• Cisplatin, Cyclopsorine

• Radiographic dye

What does an increased anion gap indicate (greater than 12)?

metabolic acidosis

WBC levels can be effected by what drugs?

Increase: systemic steroids

Decrease: “3 C’s and an I”

• Clozapine

• Carbamazepine

• Chemotherapy

• Immunosuppressants

Just say:“3 C’s and an I drop the WBC.”

What are neutrophils and what are they used for?

Neutrophils: polymorphonuclear cells/PMNs or Segs

• Bands are immature neutrophils released from bone marrow to fight infection; cause a left shift when activated

Used to assess the likelihood of acute infection and to calculate ANC

Eosinophil levels increase when there is

parasitic infection, asthma, drug allergy

Basophils levels increase when there is

hypersensitivity reaction

What can increase and decrease Lymphocytes levels?

Increase: viral infections, lymphoma.

Decrease: bone marrow suppression, HIV, steroids

What can increase or decrease RBCs?

Increase: ESAs

Decrease: chemo, anemias

What can increase and decrease Hemoglobin (Hgb)

Increase: ESAs.

Decrease: anemias, bleeding

What is the MCV and what can effect it?

MCV: size and volume of RBCs

• Increase/Marcolytic anemia: B12, folate(B9) deficiency.

• Decrease/Microlytic anemia: iron deficiency

Folic acid (B9) can be decreased by what?

“3P + MB”

• Phenytoin

• Phenobarbital(ASM)

• Primidone

• Methotrexate

• Bactrim

Just say:

“3P + MB decreases folate.”

Vitamin B12 can be decreased by?

• PPIs

• Metformin

• Can → Colchicine

• Cause → Chloramphenicol

Just remember the sentence: “PPIs and Metformin Can Cause low B12.”

Drugs that can make a Coombs test positive?

1. Beta-lactams

• Penicillins (PCNs)

• Cephalosporins

2. Sulfa-related

• Sulfas

• Dapsone

3. TB drugs

• Isoniazid (INH)

• Rifampin

4. Parkinson’s / Dopamine drugs

• Levodopa / Methyldopa

5. “Quinine family” + others

• Quinidine

• Quinine

• Primaquine

• Methylene blue

• Rasburicase / Pegloticase

Those G6PD deficiency should avoid what drugs?

What is Anti Xa?

Lab value used to monitor LMWH and UFH

• for LMWH: obtain peak 4 hours after dose

• for UFH: obtain levels after IV starts and every 6 hours until therapeutic

Recommended monitoring LMWH in pregnancy

What is a Prothrombin Time/International Normalized ratio(PT/INR) and what can it be affected by?

Monitors warfarin levels

false elevations seen with Daptomycin, Oritavancin, Telavancin

You can remember the false elevators for both tests as: “Oritavancin & Telavancin mess with both aPTT and INR.”

What is aPTT/PTT monitor and what can affect its levels?

Monitors UFH & Direct thrombin inhibitors(i.e argatroban)

Falsely elevated by:

• Oritavancin(ABx)

• Telavancin(ABx)

You can remember the false elevators for both tests as: “Oritavancin & Telavancin mess with both aPTT and INR.”

What can cause Platelet levels to decrease?

• Heparins

• Fondaparinux

• Linezolid

• Valproic acid

What is HIT and how is it diagnosed?

when platelets drop > 50% from baseline d/t UFH or LMWH.

Diagnosis: If ELISA + → SRA (serotonin release assay) to confirm

What can decrease Albumin levels and what does drugs are affected?

are decreased in cirrhosis and malnutrition.

Low levels impact highly protein-bound drugs—> warfarin, calcium, and phenytoin

• phenytoin and Ca require level adjustment when low

What are AST and ALT

enzymes released d/t hepatic injury

What is Bilirubin used for?

used with other liver tests to determine cause of liver injury and bile duct blockade

What do we use Ammonia levels for and what can affect its levels?

often measured in suspected hepatic encephalopathy

• “ammonia associated with confusion”

increases in valproate and topiramate(topamax; confusion)

decreases with lactulose

What is Creatine kinase (CK, CPK) and what can increase its levels?

Assesses muscle inflammation or muscle damage.

can be increased via: “DS + TRD”

• Daptomycin

• Statins

• Tenofovir

• Raltegravir

• Dolutegravir

Daptomycin + Statins + the integrase inhibitors (Raltegravir & Dolutegravir) + Tenofovir

What is Troponin T(TnT), Troponin I(TnI) BNP, pro-BNP?

• TnT and TnI are used in the diagnosis of MI

• BNP and NT-pro BNP are are markers of cardiac stress

  • non-specific to Heart failure or a disease state but higher values indicate a higher likelihood of heart failure

What are the Cholesterol goals?

• Total cholesterol: <200 mg/dL

• Low Density Lipoprotein(LDL): <100 mg/dL

• High Density Lipoprotein(HDL): > 40 mg/dL for men or >50 mg/dL for women

• Non-HDL: <130 mg/dL

• Triglycerides(TG): <150

What is the Fasting LDL calculated (Friedwald equation)?

LDL = TC - HDL - (TG/5)

Only can be used if TG <400

Meds that increase LDL & TG

• HIV meds (efavirenz, protease inhibitors)
• Atypical antipsychotics (olanzapine)
• Diuretics (loops, thiazides)
• Immunosuppressants (CSA/TAC)

"HADI"

Meds that increase LDL only

• Fibrates (when TG are high)
• Fish oils (except vascepa)

Meds that increase TG only

• Bile acid sequestrants
• Propofol/Clevidipine

How to interpret Fasting plasma glucose results?

• DM: >126 mg/dL

• Pre-DM: 100-125 mg/dL.

Note: Fasting begins >8 hrs prior to blood draw

What is an HbA1c and the goals for patients based on the ADA and AACE?

HbA1C measures the average blood glucose over the past 3 months

Goal:

• ADA < 7%

• AACE ≤ 6.5%

What is the ADA glucose goals?

estimated Average Glucose: <154 mg/dL

• used to correlate a finger stick with an A1C.

• an eAG of 126 correlated with an A1C of 6%

Preprandial(before meals): 80-130 mg/dL

Postprandial(after a meal): <180 mg/dL

What test can be done to distinguish Type 1 and Type 2 DM?

C-peptide(fasting)

insulin is a polypeptide

What are Amylase and Lipase and what can cause there levels to increase?

Pancreatic enzymes

GDVH

• GLP-1 agonists

• DPP-4 inhibitors

• Valproic acid

• Hypertriglyceridemia

Just say: “GDVH raises amylase and lipase.”

What medications can cause either increased or decreased TSH levels?

Amiodarone, interferon

What drugs are known to only increase thyroid(TSH) levels?

lithium

carbamazepine

Tyrosine kinase inhibitors (TKIs)

What can increase Uric Acid?

High URIC ACID/GOUT is preventing me from DANCing

• Diuretics

• ASA (aspirin)

• Niacin (B3)

• Cyclosporine/ Chemo

What drugs known to cause liver damage?(DILI)

Highest-yield (must know)

• Hydralazine

• Procainamide

• Isoniazid (INH)

These three are by far the most classic and highest risk.

Other important ones

• Quinidine

• Minocycline

• Methyldopa

• Chlorpromazine

• TNF-α inhibitors (e.g., etanercept, infliximab, adalimumab)

What can be used to indicate immunosuppression?

CD4 lymphocyte count <200

What does a positive Human chorionic gonadotropin (hCG) indicate?

Indicates pregnancy

What does a + Luteinizing hormone (LH) mean?

ovulation

What does lactic acid/lactate indicate and what can increase it?

Indicates anaerobic metabolism

Increased by NRTIs, metformin, alcohol

What drugs can increase prolactin?

Haloperidol

Risperidone

Paliperidone

Purified protein derivative (PPD) skin test is used for

indicating TB exposure/infection

Rapid plasma reagin (RPR) or VDRL is used for

Antibody test for syphilis; requires confirmatory testing if positive

What does Thiopurine Methyltransferase(TPMT) indicate?

increase risk of myelosupression and patients need lower doses of azathioprine and mercatopurine

Drugs requiring Therapeutic Drug Monitoring (TDM)

With Very Persistent People, Therapeutic monitoring Can Definitely Lead To Good Vibes”

• Warfarin

• Vancomycin

• Phenytoin / Fosphenytoin

• Procainamide

• Theophylline

• Carbamazepine

• Digoxin

• Lithium

• Tobramycin

• Gentamicin

• Valproic acid

Carbamazepine TDM

4-12 mcg/mL

Digoxin level in Afib?

0.8-2.0 ng/mL

Digoxin level HF?

0.5-0.9 ng/ml

Gentamicin & Tobramycin levels

Peak: 5-10 mcg/mL

Trough: <2 mcg/mL

Lithium trough level

0.6-1.2 mEq/L

Phenytoin/fosphenytoin level

Total: 10-20 mcg/mL (correct for low albumin)

Free : 1-2 mcg/mL

Procainamide levels

Procnamide: 4-10 mcg/mL

NAPA: 12.0 to 18.0 mcg/mL

Combined procainamide + NAPA therapeutic range: 10.0 to 30.0 mcg/mL

Theophylline level

5-15 mcg/mL

Valproic acid

50-100 mcg/mL (correct for low albumin)

Vancomycin level

Trough 15-20 mcg/mL for severe (pneumonia, endocarditis, osteo, meningitis, bacteremia) infection or AUC/MIC ratio of 400-600

Trough 10-15 mcg/mL for others (cellulitis)

Warfarin level

INR 2.0-3.0 (2.5-3.5 for mechanical mitral valve)

What is there to know about TDM?

Peak: highest concentration of drug

Trough: the lowest concentration taken right before next dose

Drug levels are Draw at steady-state (5 half-lives)

• when drugs have a Narrow Therapeutic index → narrow range between sub- and supratherapeutic toxic concentrations