Interpretation of Common Laboratory Tests

Updates (last updated November 4, 2014)

November 4, 2014

  • Renal - Added link to eGFR calculator under the Renal topic-->comments
  • Gout - Added additional comment about uric acid levels
  • Culture and Sensitivity - added comment about treating asymptomatic, but postive C&S for UTIs
  • Liver - Added statins to med list, added albumin and normal ranges.
  • Thyroid - Added comments about monitoring during pregnancy, added normal ranges for TSH and fT4
  • Lipids - Added normal ranges for HDL and LDL

October 21, 2014

  • Initial posting
Introduction

This manual is intended to serve as a general overview for recommend laboratory tests for conditions and medications commonly encountered by pharmacists. It is NOT intended to guide treatment decisions or provide in-depth knowledge of lab tests.

Each topic will cover these areas:

1. Drugs that treat

  • These are drugs commonly used for the condition.  Thus, if someone is on a drug in this category, the "lab tests / recommendations" section might apply to them

2. Drugs that cause or worsen

  • These are drugs that can cause or exacerbate the condition.  Thus, if someone had abnormal lab tests for their condition, this can serve as a guide for identifying potential causes.  It may also indicate the need for more frequent monitoring if initiated on one of these drugs

3. Lab tests / recommendations

  • Highlights lab tests used to diagnosis the condition, and also monitor for treatment efficacy and safety.  Suggested frequency of testing will also be highlighted.

4. Comments

    • Additional clinical tips will be presented here

Please note: normal ranges of various lab tests vary among facilities.  Thus, ranges reported here may differ compared to what a laboratory reports.

Abbreviations

ACE= angiotensin converting enzyme
ALP= alkaline phosphatase
ALT=alanine aminotransferase
Apo-B = apolipoprotein B
ARB= angiotensin receptor blocker
ASA = acetylsalicylic acid
AST= aspartate aminotransferase

CAI = carbonic anhydrase inhibitor
CBC= complete blood count
CK= creatine kinase
CVD= cardiovascular disease

eGFR= estimated glomerular filtration rate

fT3= free tri-iodothyronine
fT4 = free tetraiodothyronine

GAS = group A streptococcus

H2RA= histamine-2 receptor antagonist
HbA1C= glycated hemoglobin
HDL= high density lipoprotein
Hgb=hemoglobin
hsCRP= high sensitivity C-reactive protein
hx= history

K+= potassium

LDL= low density lipoprotein

MCV= mean corpuscular volume
Mg2+ = magnesium

NOAC = new oral anticoagulant
NSAID = non-steroidal anti-inflammatory drug

PPI = proton pump inhibitor

SSRI=selective serotonin receptor inhibitor

T1DM = type 1 diabetes mellitus
T3= tri-iodothyronine
T4= tetraiodothyronine
TBG=thyroid-binding globulin
TC= total cholesterol
TG= triglycerides
TMP = trimethoprim
TSH=thyroid stimulating hormone
tx= treatment

ULN = upper limit of normal

UTI = urinary tract infection

Anemia

Anemia

- Hgb of less than 135 g/L in men and 120 g/L in women

 

1) Iron-Deficiency Anemia


D
rugs that treat

  • Iron salts

Drugs that cause or worsen

  • ↓ absorption of supplements; dietary iron unaffected:
    • Antacids, H2RAs, PPIs
    • Azathioprine
    • Cholestyramine, colestipol
    • Pancreatic enzymes
    • Quinolones, tetracyclines

Lab tests / Recommendations

Diagnosis:

  • Ferritin ↓

 Monitor response:

  • Symptoms improve in a few days
  • Hgb ↑ 10-20 g/L in 2 - 4 weeks
  • Ferritin normal in 6 months

 Comments

  • Do not use iron supplements unless proven iron deficiency.
  • Once ferritin normal, discontinue unless ongoing need / blood loss.

2)  Anemia of Chronic Disease

Lab tests / Recommendations

Diagnosis

  • Ferritin normal or ↑

Comments

  • Optimize treatment of underlying disorder;
  • Iron supplements usually NOT beneficial

  

3) Macrocytic Anemia

Drugs that treat

  • Methyl /Cyano-cobalamin
  • Folic Acid

Drugs that cause or worsen 

 

Folate ↓

B12 ↓

Antacids

 

Antibiotics (chronic)

ASA (high dose, chronic)

 

Cholestyramine, colestipol

H2RAs, PPIs (chronic)

Methotrexate

 

Metformin

Phenytoin

Carbamazepine, phenobarbital, valproate

 

Sulfasalazine


Lab tests / Recommendations

Diagnosis

  • MCV ↑
  • Cobalamin (B12) ↓
  • Risk factors for folate deficiency

 Monitor response

  • Symptom improvement
  • Hgb ↑
  • Cobalamin (B12) normal in 6 months

Comments

  • Check B12 levels before supplementing with folic acid alone if risk of B12 deficiency.
  • Not usually necessary to monitor folate level.
Electrolytes

1) Potassium-hypokalemia


D
rugs that treat

  • K+ salts

Drugs that may cause or worsen

  • beta2-agonists
  • caffeine
  • corticosteroid therapy
  • insulin
  • laxatives
  • loop diuretics
  • thiazide diuretics
  • theophylline 

Lab tests / Recommendations

Diagnosis

  • Mild: K+ 3.1–3.5  mmol/L
  • Moderate: K+ 2.5–3 mmol/L
  • Severe: less than 2.5 mmol/L
  • Mg2+ less than 0.7 mmol/L

Monitor response

  • Check levels every 3-4 months if long-term K+ supplements 

Comments

  • Consider reducing /stopping medication leading to K+ loss.
  • If mild (no ongoing losses or conditions requiring prompt treatment), dietary intake of K+-rich foods may be first choice.
  • If ongoing loss, K+ supplements or K+-sparing diuretics will be needed.
  • Hypokalemia and hypomagnesemia often coexist as a result of drugs (diuretic administration) or disease states (diarrhea).
  • Mg2+ deficiency should be corrected first, otherwise difficult to normalize K+ levels.

2) Potassium - Hyperkalemia

Drugs that treat

  • beta2-agonists
  • furosemide
  • sodium polystyrene (Kayexalate) 

Drugs that cause or worsen

  • ACE inhibitors and ARBs
  • beta-blockers
  • cyclosporine
  • digoxin toxicity
  • drospirenone
  • heparin
  • ketoconazole
  • NSAIDs
  • penicillin G
  • K+-sparing diuretics
  • K+ supplements
  • tacrolimus
  • trimethoprim, co-trimoxazole
     

Lab tests / Recommendations

Diagnosis

  • Mild: K+ 5.1–6 mmol/L
  • Moderate: K+ 6.1–6.9 mmol/L
  • Severe: K+ more than 7 mmol/L

Monitor response

  • Check K+ levels (every 1–3 mo.) 

Comments

  • High risk with combination of meds that ↑ K+. Check K+ 3 and 7 days after starting combination or dosage increases, then once monthly for 3 months, then every 3 months.

3) Sodium - hyponatremia

Drugs that treat

  • Emergency room treatment

Drugs that cause or worsen

  • ACE inhibitors
  • antipsychotics
  • benzodiazepines
  • carbamazepine
  • loop diuretics (rare)
  • SSRIs
  • thiazide diuretics

 Lab tests / Recommendations

Diagnosis

  • Mild: 125-134 mmol/L
  • Moderate: 115–124 mmol/L
  • Severe: less than 115 mmol/L

Monitor response

  • Follow- up monitoring 10–14 days after initiation of therapy with diuretic or after a dose increase. 

Comments

  • Elderly, patients with diabetes at higher risk.
  • Reduce dose or stop drug responsible for ↑ sodium 
Gout

1) Uric Acid

Drugs that treat

  • allopurinol
  • febuxostat
  • sulfinpyrazone (not commonly used as a uricosuric agent)

Drugs that cause or worsen

  • alcohol
  • cyclosporin
  • diuretics (loop and thiazide)
  • levodopa
  • low-dose ASA
  • tacrolimus

Lab tests / Recommendations

Diagnosis

  • >360 µmol/L + symptoms
     

Monitor response

  • Titrate doses to achieve:
    • <360 µmol/L
    • <300 µmol/L in those with persistent gout symptoms 

Frequency

  • Every 2-5 weeks until target achieved
  • Once stable, every 6 months


C
omments

  • Many patients are asymptomatic with urate levels >360 µmol/L; do not treat if no symptoms.
  • The saturation point of monosodium urate in the extracellular fluid has been estimated to be 360-405 µmol/L; therefore, the target concentration is <360 µmol/L.
  • Uric acid may be low to normal during an acute attack
Renal Function

1) If eGFR is <25-30 ml/min:


Avoid: Increased risk of toxicity

  • baclofen
  • bisphosphonates
  • colchicine
  • glyburide
  • Mg2+-containing meds (antacids,laxatives)
  • meperidine
  • metformin
  • methotrexate
  • NOACs  – apixaban, dabigatran, rivaroxaban
  • NSAIDs, celecoxib
  • K+-sparing diuretics
  • sotalol
  • vitamin A
  • vitamin C


Avoid: ineffective

  • CAIs – acetazolamide, methazolamide (cut-off not indicated in monographs)
  • nitrofurantoin (use alternate agent when eGFR less than 60 ml/min)
  • probenecid (avoid use if eGFR less than 30 ml/min)
  • thiazide diuretics (switch to loop diuretic if eGFR less than 50 ml/min)

Adjust dose and/or dosage interval:

  • Drugs with renal elimination greater than 50%.
  • Check dosage section in drug monographs or e-therapeutics – Appendices -Dosage Adjustment in Renal Impairment.

Comments

  • The Cockcroft Gault equation provides a sufficiently accurate estimate for initial adjustment of drug dosage. Subsequent doses should be based on patient response.
  • If eGFR is greater than 60 ml/min, empiric dosage adjustments are usually not required.
  • eGFR cannot be used for dose adjustment if kidney function is rapidly changing.
  • When possible, be conservative – start with low dose (1/4 to 1/2 usual starting dose) and titrate up to lowest effective dose.
  • Antimicrobial dose reductions are often delayed for 24-48 hours to allow for aggressive dosing/drug to reach steady state.
  • Co-trimoxazole, ciprofloxacin, cimetidine, fenofibrate interfere with creatinine excretion; leads to erroneous estimate of GFR
  • CrCl as estimate of GFR questionable in elderly.
  • For an up-to-date calculator for eGFR, visit: http://www.globalrph.com/multiple_crcl_2012.htm
    • A report will be given for the eGFR based on different methods of calculating, with the most appropriate one highlighted for your patient
Vitamin D

1) Vitamin D - toxicity

Drugs that can cause or worsen

  • alfacalcidol
  • calcitriol
  • cholecalciferol ( Vitamin D3)
  • ergocalciferol ( Vitamin D2)

Lab tests / Recommendations

Serum Vitamin D

  • Greater than 250nmol/L indicates vitamin D toxicity

Comments

  • Risk of Vitamin D toxicity is low (especially if following recommended doses); routine monitoring of patients on Vitamin D supplements is not recommended.
  • Patients with chronic granuloma forming disorders, chronic fungal infections, or some with lymphoma are at risk of Vitamin D toxicity if receiving supplements -- monitor closely.

2)   Vitamin  D - deficiency

Drugs that treat

  • cholecalciferol ( Vitamin D3)
  • ergocalciferol ( Vitamin D2)

Drugs that worsen

  • anticonvulsants*
  • antifungals*
  • antiretrovirals*
  • cholestyramine
  • glucocorticoids
* Not all drugs in class reduce vitamin D levels


Lab tests / Recommendations

Serum Vitamin D
  • Less than 25 nmol/L = deficient
  • 25 – 70 nmol/L = relatively insufficient
  • 70 – 250 nmol/L = optimal
Comments
  • Only screen select patients for Vitamin D deficiency, including those taking these drugs long term.
  • Co-morbidities that warrant Vitamin D screening available in Table 2 at http://tinyurl.com/lbno3zo


Culture and Sensitivity

1) UTI - Acute and uncomplicated in women

Drugs that treat

  • nitrofurantoin
  • TMP or co-trimoxazole
  • fluoroquinolones
  • cephalexin
  • fosfomycin

Lab tests / Recommendations

Diagnosis

  • Symptoms +/- urinalysis
  • Culture usually not recommended

Comments

  • Culture indicated if failure to respond to empiric therapy, early (<1 month) recurrence following therapy, diagnostic uncertainty, pregnant patient, or pyelonephritis suspected (flank pain and fever +/- UTI symptoms).
  • A patient with a culture and sensitivity positive for a UTI, but is asymptomatic, should NOT be treated, unless immunosuppressed, or undergoing a major genitourinary procedure.  
    • A positive C&S with no symptoms is very common in the elderly, and those with chronic catheter placement or a spinal cord injury.
  • Note: nitrofurantoin is not effective for pyelonephritis.


2) GAS - strep throat

Drugs that treat

  • penicillin V
  • amoxicillin
  • erythromycin

Lab tests / Recommendations

Diagnosis

  • Throat culture
  • Rapid antigen detection test in office (not commonly used)

Comments

  • If patient is on an antibiotic, it should be stopped if culture negative.
  • If culture positive, starting an antibiotic within 10 days will prevent GAS complications such as rheumatic fever.
Liver

Enzymes (AST, ALT, ALP)

Drugs that cause or worsen

  • acarbose
  • acitretin
  • amiodarone
  • antiretrovirals (several)
  • carbamazepine
  • febuxostat
  • interferon beta-1a
  • interferon beta-1b
  • isotretinoin
  • ketoconazole
  • leflunomide
  • methotrexate
  • niacin
  • NSAIDs (esp. diclofenac)
  • rifampin
  • statins (high dose only, or in combination with other agents)
  • terbinafine
  • tizanidine
  • valproate

Lab tests / Recommendations

Normal values

  • AST approx. 10 – 35 units/L
  • ALT approx. 5 – 45 units/l
  • ALP approx. 30 – 120 units/L
  • Albumin approx 35-50 g/L

Monitor

  • Check baseline liver enzymes. 

Subsequent Frequency

  • Depends on drug; check monograph.

Comments

  • Generally, AST/ALT indicate hepatocellular disease; ALP indicates cholestatic disease. Drugs cause different patterns of hepatic injury.
  • These are common drugs for which regular monitoring is recommended.
    • There are many other drugs for which liver monitoring is recommended.
    • If a patient has underlying liver disease, it is prudent to keep a lower threshold of suspicion.
  • In the event of elevated enzymes, LiverTox can help determine if it may be drug-related: http://www.livertox.nih.gov/
  • If ALT <2-3x ULN and no symptoms, enzymes likely will recover either with no action or with discontinuation.
  • If drug-induced hepatotoxicity suspected, discontinue drug, treat symptomatically.
  • Statins DO NOT require routine liver function tests unless patient is on a high dose, a combination of lipid lowering drugs, or is at risk of hepatotoxicity (eg. previous liver damage).  Suggested intervals are baseline, 3 months, 6 months, 12 months, then annually.
  • Albumin levels can help determine nature of injury (chronic liver injury = lower albumin levels), and may also determine if highly protein bound drugs need to have their dose adjusted (eg. phenytoin) 
Thyroid Disorders

1) Hypothyroidism

Drugs that treat

  • levothyroxine
  • liothyronine
  • thyroid (desiccated)

Drugs that cause or worsen

  • amiodarone
  • chelating agents* (Fe2+, Ca2+, Al3+, Mg2+, cholestyramine, colestipol)
  • estrogen*
  • lithium
  • methimazole or propylthiouracil toxicity
  • phenytoin, carbamazepine*
  • PPIs (and maybe other acid inhibitors)

    *only if taking levothyroxine

Lab tests / Recommendations

Diagnosis

  • TSH >10 mIU/L; or,
  • TSH 4.5-10 mIU/L AND
  • Symptomatic or fT4 <9 pmol/L

Monitor response

  • TSH / fT4 q6-8 weeks until stable; then q6-12 months if stable
  • Symptom improvement in ~2 weeks; euthyroid many months
  • Primary target is TSH and fT4 in normal range:
    • TSH: 0.45 - 4.5 mIU/L
    • fT4: 9-19 pmol/L (some use 13-27 pmol/L)

Comments

  • Monitor 6-8wks after dose change.
  • TSH may remain high for months after treatment initiated; fT4 normalizes first.
  • If subclinical hypothyroidism ( TSH 4.5-10 mIU/L, normal fT4, asymptomatic), monitor TSH and fT4 q6-12 months for change in status.
  • Pregnancy:
    • TSH targets are different depending on stage of pregnancy.  Thyroid hormone needs also increase during pregnancy.  This means a dose increase of up to 25-50% of thyroid hormone is often needed.  Targets:
      • Pre‐conception: TSH < 2.5 mIU/L
      • 1st trimester: TSH < 2.5 mIU/L
      • 2nd trimester: TSH < 3 mIU/L
      • 3rd trimester: TSH < 3.5 mIU/L

2) Hyperthyroidism

Drugs that treat

  • Methimazole
  • Propylthiouracil

Drugs that cause or worsen

  • Lithium (more likely than hypothyroidism)
  • Amiodarone (mroe likely than hypothyroidism)
  • Levothyroxine toxicity

Lab tests / Recommendations

Diagnosis

  • TSH <0.1 mIU/L; or,
  • TSH 0.1 – 0.45 mIU/L AND symptomatic or fT3 >5.7 pmol/L or fT4 >19 pmol/L

Monitor response

  • TSH / fT4 / fT3 q4-6 weeks until stable; then just TSH q2-6 months
  • Symptom improvement in ~3-4 weeks, euthyroid ~4-12 weeks

Comments

  • Methimazole and propylthiouracil may require additional monitoring (CBCs and liver enzymes baseline and at 1 week).
  • If subclinical hyperthyroidism (TSH 0.1 – 0.45 mIU/L, normal fT4/fT3, asymptomatic), monitor TSH q3-6 months and symptoms for change in status.
Dyslipidemia

1) Lipid Panel

Drugs that treat

  • statins
  • fibrates
  • resins
  • ezetimibe

 

Drugs that cause or worsen

  • antiretrovirals*
  • atypical antipsychotics (esp. clozapine, olanzapine)
  • beta-blockers (except pindolol and atenolol)
  • corticosteroids
  • estrogens, oral

    *Not all affect lipid panel in same way or to same degree; check product monographs

 

Lab tests / Recommendations


P
rimary values

  • LDL (normal range: <3.5 mmol/L)*
  • HDL (normal range: Men, >1.0 mmol/L; women, >1.3 mmol/L)*
  • TC
  • TG (normal range: <2.2 mmol/L)*

Other values

  • Apo-B
  • TC: HDL ratio (calculated)
  • Non-HDL-C (calculated) 

Comments

  • Decision to initiate treatment must be based on patient’s risk category AND their lipid panel (See Canadian Dyslipidemia Guidelines, figure 2 and 3: http://tinyurl.com/nhec4f7)
  • Primary target of LDL <2 mmol/L or >50% decrease.
  • If on treatment, panel should be tested every 4-6 months until stable, then LDL yearly.
  • TC: HDL ratio used to define high risk patients, but not used as a treatment target.
  • hsCRP no longer recommended in diagnosis or as a treatment target.
  • *These ranges are for a healthy population.  For those at high risk of cardiovascular complications, different targets are recommended.  See Canadian Dyslipidemia Guidelines, above.

2) Statins

Lab tests / Recommendations

Safety

  • Liver enzymes – baseline and at 3 months
  • CK – baseline only

Efficacy

  • Same as listed under “lipid panel lab tests”

Comments

  • Routine testing of liver enzymes and CK not indicated for most patients; consider more frequent testing if high dose, combination therapy, or previous liver injury.
  • See supplement 1 for when to test and how to interpret CK.
Diabetes

1) HbA1C

Drugs that treat

  • hypoglycemic Drugs

 

Drugs that cause or worsen

  • beta2-agonists
  • caffeine
  • chlorpromazine
  • corticosteroids
  • cyclophosphamide
  • diltiazem
  • estrogens
  • furosemide
  • haloperidol
  • indomethacin
  • isoniazid
  • levodopa
  • lithium
  • methyldopa
  • nicotine
  • oral contraceptives
  • phenytoin
  • protease inhibitors
  • sirolimus
  • tacrolimus
  • sympathomimetics
  • theophylline
  • thiazide diuretics

Lab tests / Recommendations

Diagnosis

  • HbA1C ≥ 6.5%
  • Do not use for diagnosis in children, adolescents, pregnant women, or those with suspected T1DM

Monitor response

Target (HbA1C):

  • <7% for most
  • <6.5% if short duration of diabetes; no hx hypoglycemia; no significant CVD
  • 7.1-8.5% - limited life expectancy; high level of functional dependency; high risk of ischemic events; multiple  co-morbidities; hx of recurrent severe hypoglycemia; hypoglycemia unawareness; unable to achieve HbA1C <7% despite optimal tx, including insulin)

Frequency:

  • q3months initially
  • q6months once treatment and lifestyle stabilized and target consistently achieved

Comments

Interfering Factors:

  • False ↓ HbA1C
    • drugs: antiretrovirals, ASA, dapsone, epoetin, iron, ribavirin, vitamin B12, vitamin C, vitamin  E,
    • chronic liver disease
    • rheumatoid arthritis
    • splenomegaly

  • False ↑ HbA1C
    • drugs: large doses ASA, chronic opioid use
    • iron/B12 deficiency
    • alcoholism
    • splenectomy

  • Variable effects on HbA1C
    • hemoglobinopathies
    • chronic renal failure
Supplement 1: Interpreting Creatine Kinase

Adapted from RxFiles QA Summary June 2013 -- Statin Intolerance

 

Symptoms

CK Value

normal:
60-174 IU/L

Actions

Myalgia

 

  • Mild pain, cramping, weakness, soreness, aches, tenderness, stiffness
  • Usually in large muscle groups (shoulders, upper arms, thighs)


<400 IU/L

 

 

  • Consider checking CK
  • Reasssess if statin indicated
  • Stop statin if severe pain
  • If pain not tolerated, consider dose reduction or switch to another statin

Myositis

 

  • Moderate pain, cramping, weakness, soreness, aches, tenderness, stiffness
  • Usually in large muscle groups (shoulders, upper arms, thighs)
  • No increase in serum creatinine or myoglobinuria


>2-4x ULN

  • Check CK
  • Reassess if statin indicated
  • Stop statin until CK normal & patient is asymptomatic
  • Consider resuming at lower dose, or use a different statin

Rhabdo-
myolysis

  • Severe pain, cramping, weakness, soreness, aches, tenderness, stiffness
  • Usually in large muscle groups (shoulders, upper arms, thighs)
  • Increased serum creatinine
  • Myoglobinuria (dark-brown urine)


>4-10x ULN

 

  • Emergency room treatment often needed to prevent acute kidney injury
  • Check CK
  • Stop statin until CK is less than ULN and patient asymptomatic
  • If episode mild, may re-challenge with low-dose of another statin
  • If moderate-severe, specialist referral necessary
Supplement 2: Drug Interactions with Thyroid Tests

The following table shows drugs which may affect the laboratory results of thyroid function tests, but do not cause thyroid dysfunction in euthyroid patients. 

These drugs may cause temporary increases or decreases in overall thyroid function, but values soon return to normal if euthyroid.  If the patient is not euthyroid, these could exacerbate their condition.

Other drugs that impact thyroid function are listed in the Thyroid section.

Mechanism

Drugs

Effect on thyroid function

Decreases serum TBG

androgens, danazol, glucocorticoids

Increases

Decreases T4 binding to TBG

furosemide, NSAIDs (some), salicylates,

Increases

Increases serum TBG

estrogens, heroin, methadone, raloxifene, tamoxifen,

Decreases

Increases T4 clearance

carbamazepine, phenobarbital, phenytoin, rifampin

Decreases

Suppresses TSH secretion

dobutamine, glucocorticoids, octreotide

Decreases

Impairs conversion of T4 to T3

glucocorticoids, nadolol  propranolol

Decreases

Supplement 3: References and additional tools

Available on-line, free access

Guidelines

 

Mobile

  • “Pocket Lab Values” on Android and iPhone ($5)

 

Textbook

  • Lee  M. Basic skills in interpreting laboratory data. 4th Ed. Bethesda: American-Society of Health-Systems Pharmacists; 2009.
Index

Use the index to quickly screen if a drug might impact certain lab tests, conditions, or require further monitoring.

DRUGS

FOUND IN TOPIC

abacavir

see antiretrovirals

acarbose

Liver function,  see hypoglycemic drugs

acebutolol

see beta-blockers

ACEIs

Electrolytes

acetazolamide

see CAIs

acitretin

Liver function

alcohol

Gout

alendronate

see bisphosphonates

alfacalcidol

Vitamin D

allopurinol

Gout

alprazolam

see benzodiazepines

aluminum

Thyroid

amiloride

see diuretics,  K+-sparing

amiodarone

Liver function,  Thyroid

amoxicillin 

Culture and Sensitivity

androgens 

Supplement Three

antacids  

Anemia, Renal Function

antibiotics chronic   

Anemia

anticonvulsants  

Vitamin D

antifungals  

Vitamin D

antipsychotics atypical 

Dyslipidemia

antipsychotics   

Electrolytes

antiretrovirals    

Vitamin D, Liver function, Dyslipidemia, Diabetes

apixaban

see NOACs

ARBs

Electrolytes

aripiprazole

see antipsychotics,  atypical

ASA (acetylsalicylic acid)    

Anemia, Gout, Diabetes, Supplement Three

asenapine

see antipsychotics,  atypical

atazanavir

see antiretrovirals

atenolol

see beta-blockers

atorvastatin

see statins

azilsartan

see ARBs

baclofen 

Renal Function

benazepril

see ACEIs

benzodiazepines 

Electrolytes

beta2-agonists    

Electrolytes, Dyslipidemia, Diabetes

beta-blockers 

Electrolytes

bezafibrate

see fibrates

bisoprolol

see beta-blockers

bisphosphonates 

Renal Function

bromazepam

see benzodiazepine

bumetanide

see diuretics,  loop

CAIs (carbonic anhydrase inhibitors) 

Renal Function

caffeine  

Electrolytes, Diabetes

calcitriol 

Vitamin D

calcium 

Thyroid

canagliflozin

see hypoglycemic drugs

candesartan

see ARBs

captopril

see ACEIs

carbamazepine     

Anemia, Electrolytes, Liver function, Thyroid, Supplement Three

celecoxib 

Renal Function

cephalexin 

Culture and Sensitivity

chlordiazepoxide

see benzodiazepines

chlorpromazine 

Diabetes

chlorpropamide

see hypoglycemic drugs

chlorthalidone

see diuretics,  thiazides

cholecalciferol 

Vitamin D

cholestyramine

see resins

cilazapril

see ACEIs

cimetidine

see H2RAs, Renal Function

ciprofloxacin  

see fluoroquinolones,   Renal Function

citalopram

see SSRIs

clonazepam

see benzodiazepines

clorazepate

see benzodiazepines

clozapine

see antipsychotics,  atypical

colchicine 

Renal Function

colesevelam

see resins

colestipol

see resins

contraceptives, oral

Diabetes

cotrimoxazole   

Electrolytes, Renal Function, Culture and Sensitivity

cyanocobalamin 

Anemia

cyclophosphamide 

Diabetes

cyclosporine  

Electrolytes, Gout

dabigatran

see NOACs

danazol 

Supplement Three

dapsone 

Diabetes

darunavir

see antiretrovirals

delaviridine

see antiretrovirals

dexlansoprazole

see PPIs

diazepam

see benzodiazepines

diclofenac

see NSAIDs

didanosine

see antiretrovirals

diflunisal

see NSAIDs

digoxin, toxicity 

Electrolytes

diltiazem 

Diabetes

diuretics, loop

Electrolytes, Gout, Supplement Three

diuretics, potassium-sparing

Electrolytes, Renal Function

diuretics, thiazide

Electrolytes, Gout, Renal Function, Dyslipidemia, Diabetes

dobutamine 

Supplement Three

doxycycline

see tetracycline

drospirenone 

Electrolytes

efavirenz

see antiretrovirals

emtricitabine

see antiretrovirals

enalapril

see ACEIs

enfuviritide

see antiretrovirals

eplerenone

see diuretics,  potassium-sparing

epoetin 

Diabetes

eprosartan

see ARBs

ergocalciferol 

Vitamin D

erythromycin 

Culture and Sensitivity

escitalopram

see SSRIs

esomeprazole

see PPIs

estrogen   

Thyroid, Dyslipidemia, Diabetes, Supplement Three

ethacrynic acid 

see diuretics,  loop

etidronate

see bisphosphonates

etodolac

see NSAIDs

etravirine

see antiretrovirals

exenetide

see hypoglycemic drugs

ezetimibe 

Dyslipidemia

famotidine

see H2RAs

febuoxostat  

Gout, Liver function

fenofibrate  

see fibrates,  Renal Function

fibrates 

Dyslipidemia

floctafenine

see NSAIDs

fluoroquinolones   

Anemia, Culture and Sensitivity

fluoxetine

see SSRIs

flurazepam

see benzodiazepines

flurbiprofen

see NSAIDs

fluvastatin

see statins

fluvoxamine

see SSRIs

folic acid

 Anemia

formoterol

see beta2-agonists

fosamprenavir

see antiretrovirals

fosfomycin

Culture and Sensitivity

fosinopril

see ACEIs

furosemide

see diuretics,  loop;  Electrolytes,  Diabetes,  Supplement Three,  

gemfibrozil

see fibrates

gliclazide

see hypoglycemic drugs

glimepiride

see hypoglycemic drugs

glucocorticoids      

Electrolytes, Vitamin D, Dyslipidemia, Diabetes, Supplement Three

glyburide  

see hypoglycemic drugs,  Renal Function

H2RAs (H2receptor antagonists) 

Anemia

haloperidol 

Diabetes

heparin 

Electrolytes

heroin 

Supplement Three

hydrochlorothiazide

see diuretics,  thiazides

hypoglycemic drugs 

Diabetes

ibuprofen

see NSAIDs

indapamide

see diuretics,  thiazides

indinavir

see antiretrovirals

indomethacin  

see NSAIDs,  Diabetes

insulin  

see hypoglycemic drugs,  Electrolytes

insulin aspart

see hypoglycemic drugs

insulin detemir

see hypoglycemic drugs

insulin glargine

see hypoglycemic drugs

insulin glulisine

see hypoglycemic drugs

insulin lispro

see hypoglycemic drugs

interferon beta-a

Liver function

interferon beta-b 

Liver function

irbesartan

see ARBs

iron  

Anemia, Thyroid, Diabetes

isoniazid 

Diabetes

isotretinoin 

Liver function

ketoconazole  

Electrolytes, Liver function

ketoprofen

see NSAIDs

ketorolac

see NSAIDs

labetalol

see beta-blockers

lamivudine

see antiretrovirals

lansoprazole

see PPIs

laxatives 

Electrolytes

leflunomide 

Liver function

levodopa  

Gout, Diabetes

levofloxacin

see fluoroquinolones

levothyroxine 

Thyroid

linagliptin

see hypoglycemic drugs

liothyroxine 

Thyroid

liraglutide

see hypoglycemic drugs

lisinopril

see ACEIs

lithium  

Thyroid, Diabetes

lopinavir-ritonavir

see antiretrovirals

lorazepam

see benzodiazepines

losartan

see ARBs

lovastatin

see statins

lurasidone

see antipsychotics,  atypical

magnesium 

Thyroid

magnesium-containing antacids 

Renal Function

magnesium-containing laxatives 

Renal Function

maraviroc

see antiretrovirals

mefenamic acid

see NSAIDs

meloxicam

see NSAIDs

meperidine 

Renal Function

metformin  

see hypoglycemic drugs; Anemia, Renal Function

methadone

see opioids; Supplement Three

methazolamide

see CAIs

methimazole 

Thyroid

methotrexate   

Anemia, Renal Function, Liver function

methylcobalamin 

Anemia

methyldopa 

Diabetes

metolazone

see diuretics,  thiazide

metoprolol

see beta-blockers

minocycline

see tetracycline

moxifloxacin

see fluoroquinolones

nabumetone

see NSAIDs

nadolol

see beta-blockers;  Supplement Three

naproxen

see NSAIDs

nateglinide

see hypoglycemic drugs

nebivolol

see beta-blockers

nelfinavir

see antiretrovirals

neviripine

see antiretrovirals

niacin 

Liver function

nicotine 

Diabetes

nitrazepam

see benzodiazepines

nitrofurantoin  

Renal Function, Culture and Sensitivity

nizatidine

see H2RAs

NOACs (new oral anticoagulants) 

Renal Function

norfloxacin

see fluoroquinolones

NSAIDs (nonsteroidal antiinflammatory drugs) 

Electrolytes,  Renal Function,  Liver function,  Supplement Three

octreotide 

Supplement Three

ofloxacin

see fluoroquinolones

olanzapine

see antipsychotics,  atypical

olmesartan

see ARBs

omeprazole

see PPIs

opioids, chronic

Diabetes

oxaprozin

see NSAIDs

oxazepam

see benzodiazepines

paliperidone

see antipsychotics,  atypical

pamidronate

see bisphosphonates

pancreatic enzymes 

Anemia

pantoprazole

see PPIs

paroxetine

see SSRIs

penicillin G

Electrolytes

penicillin V

Culture and Sensitivity

perindopril

see ACEIs

phenobarbital

Electrolytes,  Supplement Three

phenytoin

Anemia,  Thyroid,  Diabetes,  Supplement Three

pindolol

see beta-blockers

pioglitazone

see hypoglycemic drugs

piroxicam

see NSAIDs

potassium salts

Electrolytes

pravastatin

see statins

probenecid 

Renal Function

propranolol

see beta-blockers;  Supplement Three

propylthiouracil

Thyroid

protease inhibitors 

Diabetes

PPIs (proton pump inhibitors)  

Anemia, Thyroid

quetiapine

see antipsychotics,  atypical

rabeprazole

see PPIs

raloxifene 

Supplement Three

raltegravir

see antiretrovirals

ramipril

see ACEIs

ranitidine

see H2RAs

repaglinide

see hypoglycemic drugs

resins 

Anemia,  Vitamin D,  Thyroid,  Dyslipidemia

ribavirin 

Diabetes

rifampin  

Liver function, Supplement Three

rilpivirine

see antiretrovirals

risedronate

see bisphosphonates

risperidone

see antipsychotics,  atypical

ritonavir

see antiretrovirals

rivaroxaban

see NOACs

rosiglitazone

Diabetes

rosuvastatin

see statins

salbutamol

see beta2-agonists

salicylates 

Supplement Three

salmeterol

see beta2-agonists

saquinavir

see antiretrovirals

saxagliptin

see hypoglycemic drugs

sertraline

see SSRIs

simvastatin

see statins

sirolimus 

Diabetes

sitagliptin

see hypoglycemic drugs

sodium polystyrene 

Electrolytes

sotalol 

Renal Function

spironolactone

see diuretics,  K+-sparing

SSRIs (selective serotonin reuptake inhibitor) 

Electrolytes

statins 

Dyslipidemia
Liver

stavudine

see antiretrovirals

sulfasalazine 

Anemia

sulindac

see NSAIDs

sulfinpyrazone 

Gout

sympathomimetics 

Diabetes

tacrolimus   

Electrolytes, Gout, Diabetes

tamoxifen 

Supplement Three

telmisartan

see ARBs

temazepam

see benzodiazepines

tenofovir

see antiretrovirals

tenoxicam

see NSAIDs

terbinafine

 Liver function

terbutaline

see beta2-agonists

tetracycline 

Anemia

theophylline  

Electrolytes, Diabetes

thyroid, desiccated 

Thyroid

tiaprofenic acid

see NSAIDs

timolol

see beta-blockers

tipranavir

see antiretrovirals

tizanidine 

Liver function

tolbutamide

see hypoglycemic drugs

trandolapril

see ACEIs

triamterene

see diuretics,  K+-sparing

triazolam

see benzodiazepines

trimethoprim  

Electrolytes, Culture and Sensitivity

valproate  

Anemia, Liver function

valsartan

see ARBs

vitamin A 

Renal Function

vitamin C  

Renal Function, Diabetes

vitamin D 

Vitamin D

vitamin E 

Diabetes

ziprasidone

see antipsychotics,  atypical

zidovudine

see antiretrovirals

zoledronic acid

see bisphosphonates