A Patient’s Guide to Preparing for Specialty Lab Tests
Written by YiQiu Hu, NMD
Arizona-licensed naturopathic physician and virtual concierge medicine provider
Published August 2026 | Medically reviewed August 2026
Specialty laboratory testing may involve more preparation than routine blood work. Depending on the test, you may be asked to fast, change the timing of certain medications or supplements, collect a sample at a particular time of day, follow specific dietary instructions, or carefully store and ship a specimen from home.
But there is no single preparation protocol that applies to every specialty test.
The most important rule is simple: follow the instructions provided for your specific laboratory panel rather than assuming that every test requires fasting or the same preparation.
The U.S. National Library of Medicine's MedlinePlus guidance on laboratory preparation similarly notes that preparation varies depending on the particular test being performed.
This guide explains the most common preparation considerations so you know what questions to ask and what to check before completing your test.
If you are new to advanced testing, you may also want to begin with our Specialty Laboratory Testing: A Complete Guide for Patients or visit our Specialty Laboratory Testing Resource Center.
Why Preparation Matters for Specialty Laboratory Testing
Laboratory results can be influenced by more than your underlying health.
Depending on the biomarker being measured, results may also be affected by:
Recent meals
Hydration
Alcohol
Caffeine
Exercise
Medications
Vitamins and supplements
Time of day
Menstrual-cycle timing
Hormone medications
Recent illness
Sample-collection technique
Storage temperature
Delays in shipping or processing
For some tests, these factors make very little difference. For others, they may meaningfully change the result.
That is why good preparation is not about following the longest possible list of restrictions. It is about following the correct instructions for the specific test being performed.
Specialty testing may also use blood, urine, saliva, stool, dried blood spots, cheek swabs, or other specimens. Each collection method has its own requirements.
You can learn more about the different categories and specimen types in What Is Specialty Laboratory Testing? A Patient’s Guide.
1. Read the Instructions Before the Day of Testing
One of the easiest mistakes is waiting until the morning of your test to open the instructions.
Specialty laboratory kits may contain requirements that need to be followed hours—or occasionally days—before collection.
As soon as you receive your testing instructions or collection kit, review them for information about:
Whether fasting is required
What you may drink
Whether caffeine or alcohol should be avoided
Whether exercise should be limited
Medication or supplement considerations
The correct time of day for collection
Menstrual-cycle timing, when applicable
Foods that should be included or avoided
How samples should be labeled
Refrigeration or freezing requirements
Which day the specimen should be shipped
Whether multiple samples are required
Whether a professional blood draw is needed
If anything is unclear, contact the laboratory or the healthcare professional who ordered the test before collecting the specimen.
Trying to correct a preparation mistake after the sample has already been submitted can sometimes require repeating the collection.
2. Do Not Assume You Need to Fast
Fasting is one of the most common questions patients have before laboratory testing.
Some tests require fasting. Others do not.
For routine fasting blood tests, patients are commonly instructed to avoid food while continuing to drink plain water for a specified period. MedlinePlus notes that fasting instructions often involve approximately 8 to 12 hours, although the exact requirement depends on the test.
Specialty testing can be different.
Some panels may require:
Overnight fasting
A shorter fasting period
No fasting at all
Collection after a particular meal
Maintaining your normal diet before testing
Do not fast simply because the test involves blood.
Unnecessary fasting can make the testing experience more uncomfortable and, depending on what is being evaluated, may not reflect the physiological conditions your physician is trying to measure.
If fasting is required, follow the exact duration provided by the laboratory or your physician.
3. Know What Counts as Fasting
When a laboratory instructs you to complete a fasting blood test, plain water is generally allowed unless your instructions specifically say otherwise.
Food is not the only consideration.
Depending on the test instructions, you may also need to avoid:
Coffee
Tea
Juice
Soda
Energy drinks
Gum
Mints
Smoking
Alcohol
Exercise during the fasting period
MedlinePlus specifically advises patients undergoing a fasting blood test to avoid eating and drinking anything other than plain water and also notes that gum, smoking, and exercise can interfere with fasting preparation.
Specialty tests may have different requirements, so use the directions supplied with your particular panel as the final authority.
4. Review Your Medications Before Testing
Medications can influence certain laboratory measurements, but this does not mean that you should automatically stop taking them before testing.
Before your test, make sure your physician knows about all prescription and nonprescription medications you use.
Examples may include:
Thyroid medication
Hormone replacement therapy
Birth-control medications
Corticosteroids
Blood-pressure medications
Diabetes medications
Cholesterol medications
Anti-inflammatory medications
Antibiotics or antifungal medications
Acid-reducing medications
Diuretics
For some tests, your physician may intentionally want to measure your values while you are taking the medication.
For others, the timing of your dose in relation to sample collection may be important.
Do not discontinue a prescription medication solely because you are completing laboratory testing unless your physician or another qualified healthcare professional specifically instructs you to do so.
MedlinePlus provides the same general recommendation: patients should tell their healthcare provider about the medicines they use but should not stop them unless instructed.
5. Tell Your Physician About Vitamins and Supplements
Supplements can matter too.
Make sure your healthcare professional knows about vitamins, minerals, herbs, amino acids, nutritional powders, performance supplements, and other products you regularly use.
This is especially important when the test is designed to evaluate nutritional status.
For example, taking a nutrient shortly before testing may affect the measured concentration without necessarily providing a complete picture of longer-term nutritional status.
Depending on what is being measured, your physician may want you to:
Continue your normal supplement routine
Take supplements after the sample has been collected
Temporarily hold selected supplements
Document when your last dose was taken
The correct approach depends on the test.
6. Pay Special Attention to Biotin
Biotin deserves special mention because it can interfere with certain laboratory testing methods.
Biotin—also known as vitamin B7—is found in many:
Hair, skin, and nail supplements
Multivitamins
B-complex vitamins
Prenatal vitamins
Individual biotin supplements
Some products contain substantially more biotin than typical dietary amounts.
The appropriate amount of time to stop biotin—if stopping it is necessary—depends on the dose, laboratory method, and test being performed.
Therefore, rather than following a universal rule such as “stop biotin for 48 hours,” tell your physician and laboratory how much biotin you take and follow the instructions provided for your particular test.
7. Stay Normally Hydrated
For most blood draws, being reasonably hydrated can make venous collection easier.
However, more water is not always better.
Drinking unusually large amounts of fluid immediately before some urine or blood tests may change the concentration of certain measurements.
A practical approach is to maintain your normal hydration habits unless your testing instructions specifically tell you otherwise.
Patients with kidney disease, heart disease, fluid restrictions, or other medical conditions should follow their individualized hydration recommendations rather than deliberately increasing fluid intake for a laboratory test.
8. Avoid Making Major Diet Changes Unless You Are Told To
Patients sometimes try to “eat perfectly” for several days before laboratory testing.
That can actually work against the purpose of certain tests.
If your physician is trying to understand how your body functions under your usual conditions, dramatically changing your diet immediately before collection may make the results less representative of your normal life.
Unless instructed otherwise, continue your usual dietary pattern.
Some specialty tests, however, may require specific dietary preparation. Instructions might ask you to:
Avoid particular foods
Maintain a normal diet
Consume a particular food before testing
Avoid alcohol
Limit caffeine
Complete collection before eating
Record what you ate before the test
Follow the instructions for the individual test rather than creating your own preparation diet.
9. Consider Alcohol and Caffeine
Alcohol and caffeine can affect certain physiological measurements, but whether they need to be avoided depends on the laboratory test.
If your instructions specify a period without alcohol, coffee, tea, energy drinks, or other caffeinated products, follow that recommendation carefully.
If the instructions say nothing about these substances, do not assume that every specialty test requires avoiding them for several days.
When uncertain, ask before collection.
10. Exercise Can Affect Some Laboratory Results
Exercise temporarily changes several aspects of human physiology.
Depending on the intensity and duration of activity, strenuous exercise may influence certain metabolic, muscle, inflammatory, hormonal, or biochemical measurements.
Some laboratory panels therefore ask patients to avoid vigorous exercise for a particular period before collection.
Others do not.
If your instructions restrict exercise, follow them. Otherwise, maintaining your normal activity pattern is generally more useful than making a major last-minute change.
If you completed an unusually intense workout shortly before your laboratory test, tell your physician when your results are reviewed.
11. Timing May Matter for Hormone Testing
Hormones are not always present at the same concentration throughout the day.
Some vary according to:
Time of day
Sleep schedule
Menstrual-cycle phase
Menopausal status
Pregnancy
Hormone replacement therapy
Birth-control medications
Timing of a medication or hormone dose
For this reason, hormone testing may occasionally need to be completed during a specific time window.
Saliva and urine hormone panels may also involve multiple samples collected at different times.
If you are completing hormone testing, confirm:
What time the sample should be collected
Whether collection relates to waking or bedtime
Whether menstrual-cycle timing matters
Whether you should take your hormone medication before or after collection
Whether several samples are required
Do not change hormone medications without specific medical instructions.
For a deeper explanation of why the collection method matters, visit our Specialty Laboratory Testing Resource Center, where we cover blood, saliva, urine, and other specialty testing approaches.
12. Follow Stool Collection Instructions Carefully
Comprehensive gastrointestinal or microbiome testing commonly uses stool specimens collected at home.
Although individual kits differ, preparation may involve instructions about:
Which collection container to use
How much specimen to collect
Whether multiple samples are needed
Avoiding contamination
Whether certain medications or supplements require special consideration
Refrigerating or freezing the sample
Completing collection on particular days
Shipping the specimen promptly
Use only the containers and collection materials provided or specifically approved by the laboratory.
Do not substitute your own container.
If stool becomes contaminated or you are unsure whether the specimen was collected correctly, contact the laboratory before sending it.
13. Understand Whether Your Urine Test Is a Spot or Timed Collection
Not all urine testing is performed the same way.
A spot urine sample typically represents urine collected at a particular point in time.
A timed urine collection, such as a 24-hour urine test, is designed to measure what is excreted over a defined period.
Other specialty urine tests may use:
First-morning urine
A sample collected after waking
Multiple samples throughout the day
Urine collected before or after a specific exposure or intervention
Timing errors can affect the usefulness of some urine-based tests.
Read the collection schedule before beginning, and record collection times when instructed.
14. Saliva Collection Often Requires Specific Timing
Saliva is used in certain specialty laboratory panels, particularly when multiple measurements throughout the day are desired.
Because food, drinks, oral hygiene, blood from irritated gums, and collection timing may affect some saliva samples, laboratories commonly provide specific instructions regarding what to avoid before collection.
Follow the laboratory's directions for:
Eating and drinking
Brushing or flossing
Smoking or vaping
Exercise
Medication use
Collection time
Sample storage
If the instructions say to collect several samples during the day, set reminders so that you do not accidentally miss one of the required windows.
15. Prepare for a Specialty Blood Draw
Some specialty kits require a venous blood draw that must be completed by a phlebotomist.
Before leaving home, confirm that you have:
The laboratory requisition, if required
The specialty collection kit
All required tubes and supplies
Identification
Insurance information if applicable
Shipping materials
Any special processing instructions provided by the laboratory
Not every routine laboratory draw station processes every specialty kit.
If an outside phlebotomy location is required, confirm ahead of time that the facility can collect and process your particular test.
If you have a history of difficult blood draws, fainting, or anxiety with needles, let the phlebotomist know before the collection begins.
16. Pay Attention to Storage and Shipping
For at-home testing, correct specimen handling can be just as important as correct collection.
Some specimens must remain at room temperature.
Others may need:
Refrigeration
Freezing
A cold pack
Protection from heat
Same-day shipping
Shipment only on certain weekdays
Arizona temperatures make this particularly important.
Leaving a temperature-sensitive specimen in a hot vehicle, outdoor mailbox, or unprotected area for a prolonged period may not be appropriate for some testing kits.
Follow the laboratory's shipping instructions closely and use the supplied packaging whenever required.
If you are unsure whether a specimen has been stored correctly, contact the laboratory before shipping rather than guessing.
17. Label Every Sample Exactly as Directed
Specialty kits may contain multiple collection tubes or containers.
Before submitting them, confirm that each required specimen has been labeled with the information requested by the laboratory, which may include:
Your name
Date of birth
Collection date
Collection time
Sample number or sequence
Do not assume that an unlabeled tube can simply be matched with your paperwork later.
Correct specimen identification is an important part of laboratory processing.
18. Do Not Collect a Sample When the Instructions Say to Wait
Certain temporary circumstances may affect some specialty testing.
Depending on the test, your physician or laboratory may want to know if you have recently experienced:
Acute illness
Fever
Significant gastrointestinal illness
Antibiotic use
New medications
Major dietary changes
Recent surgery
Unusually intense exercise
Menstruation
Travel
A significant change in supplements
An environmental or occupational exposure
This does not automatically mean that testing must be postponed.
Sometimes the temporary condition is exactly what your physician wants to evaluate.
The key is to communicate the change rather than deciding on your own whether to cancel or proceed.
What If I Made a Preparation Mistake?
Mistakes happen.
Perhaps you:
Ate when you were supposed to fast
Took a supplement you were instructed to hold
Missed a urine collection
Collected a sample at the wrong time
Forgot to refrigerate a specimen
Used the wrong container
Missed a shipping deadline
Do not automatically throw away the sample, and do not send it without mentioning the issue.
Contact your physician, testing coordinator, or laboratory and explain exactly what happened.
Depending on the test, the sample may still be usable—or recollection may provide a more reliable result.
It is usually better to clarify the situation than to produce a laboratory report whose interpretation may be compromised by an avoidable collection problem.
A Simple Specialty Lab Preparation Checklist
Before completing your test, make sure you can answer these questions:
What exactly am I testing?
Do I need to fast?
If so, for how long?
Can I drink water?
Can I have coffee or tea?
Should I avoid alcohol?
Are there exercise restrictions?
Should I continue my prescription medications?
Do any vitamins or supplements require special instructions?
Do I take biotin?
Does the sample need to be collected at a particular time?
Does menstrual-cycle timing matter?
Am I collecting blood, urine, saliva, stool, or multiple specimen types?
Does the specimen need refrigeration or freezing?
When should I ship it?
Do I need to schedule a blood draw?
What should I do if I make a mistake?
If you cannot answer one of these questions and it could affect your test, clarify it before collecting the specimen.
What Happens After Your Specialty Lab Test?
Once your specimen has been received, processing time depends on the type and complexity of the test.
Specialty laboratory panels may take longer to complete than routine blood work because some involve specialized analytical methods or multiple biomarkers.
When your results become available, the report should not be interpreted in isolation.
An abnormal result does not automatically mean that you have a disease, and a result within the laboratory reference range does not necessarily answer every clinical question.
Your physician should consider the findings alongside factors such as:
Your symptoms
Medical history
Medications and supplements
Previous laboratory results
Routine blood work
Physical findings
Risk factors
Diet and lifestyle
Exposures
Other diagnostic testing
That clinical context is particularly important with advanced or emerging laboratory markers.
If you want to understand how specialty testing fits into a broader medical evaluation, explore our Specialty Laboratory Testing resources or read Understanding Laboratory Testing: A Complete Guide for Patients.
Preparation Should Match the Test
The goal of specialty laboratory preparation is not to create perfect laboratory numbers.
It is to collect a specimen under the conditions that make the results as useful and interpretable as possible.
For some patients, that means fasting.
For others, it may mean collecting a sample at a particular time, maintaining a normal diet, documenting medication use, temporarily adjusting a supplement under medical guidance, or carefully refrigerating and shipping an at-home specimen.
Because specialty laboratory tests vary so widely, the instructions provided for your individual test should always take priority over general advice found online.
When you are unsure, ask before collecting the sample.
Physician-Guided Specialty Laboratory Testing in Arizona
At Ask Dr. Hu, specialty laboratory testing begins with a clinical question rather than automatically ordering the largest available panel.
Your symptoms, health history, previous testing, medications, exposures, risk factors, goals, and budget are considered when deciding whether advanced testing is likely to provide useful information. Current Ask Dr. Hu specialty testing services include physician-guided test selection, laboratory processing, and interpretation of results within the broader clinical picture.
Learn more about our Specialty Laboratory Testing services or contact Ask Dr. Hu to discuss whether specialty testing may be appropriate for you.
Evidence, Medical Review, and Patient Education
This guide is intended to provide practical, evidence-informed patient education rather than a universal protocol for every laboratory test.
General preparation recommendations were developed with reference to patient guidance from the U.S. National Library of Medicine's MedlinePlus, including its recommendations regarding fasting, medication disclosure, and test-specific preparation.
The discussion of biotin reflects current information from the U.S. Food and Drug Administration regarding biotin interference with certain laboratory assays.
Because laboratory methods and preparation requirements differ, patients should follow the instructions provided by the laboratory and their healthcare professional for the specific test being performed.
Medical Disclaimer:
The information in this article is provided for general educational purposes and does not replace individualized medical advice, diagnosis, or treatment. Do not stop or change prescription medications, hormones, supplements, or medically necessary dietary or fluid restrictions solely for laboratory testing unless instructed by a qualified healthcare professional.
About the Author
YiQiu Hu, NMD is an Arizona-licensed naturopathic physician and the founder of Ask Dr. Hu. His clinical work includes concierge medicine, preventive healthcare, health optimization, laboratory testing, medical weight management, hormone care, integrative pain management, and individualized treatment planning. His approach emphasizes thoughtful medical evaluation, evidence-informed care, careful interpretation of laboratory findings, and helping patients understand the reasoning behind their healthcare decisions.
Learn more about Dr. YiQiu Hu and the physicians at Ask Dr. Hu.