Reading room
Lab testing guides and explainers
Background reading for anyone preparing for a lab test: how fasting works, why collection timing matters, and what results can and cannot tell you.
- Evergreen
- Plain language
- Not medical advice
Appointment Prep
- Appointment PrepAfter the Blood Draw: Bruising, Aftercare, and When to CallWhat is normal after a blood draw, how to reduce bruising, and the warning signs that mean you…
- Appointment PrepAlcohol, Caffeine, and Lab Tests: What to Avoid Before a DrawHow alcohol and caffeine can shift blood and urine results, how long their effects last, and…
- Appointment PrepCoping With Needle Anxiety at the LabPractical ways to manage a fear of needles before and during a blood draw, from breathing and…
- Appointment PrepHow to Find a Lab Collection Site and Choose the Right OneHow to find a lab collection site near you, what to confirm before booking, and how to choose…
- Appointment PrepHydration and Blood Draws: How Water Helps Your Test DayHow good hydration makes a blood draw easier, why dehydration can distort some results, and how…
- Appointment PrepMedications That Can Affect Lab Tests: What to Tell Your LabHow common prescription and over-the-counter medicines can shift lab results, why you should…
- Appointment PrepWhat to Bring to a Lab Appointment: A Simple ChecklistA practical checklist for lab day, including identification, your order or requisition…
Condition-Specific Panels
- Condition-Specific PanelsPreparing for a CBC: What a Complete Blood Count Needs From YouHow to prepare for a complete blood count, whether fasting or hydration matters, what can shift…
- Condition-Specific PanelsPreparing for a Cortisol Test: Timing, Stress, and MedicationsHow to prepare for a cortisol test, including the best collection time, the effect of stress…
- Condition-Specific PanelsPreparing for a Kidney Panel: Hydration, Timing, and MedicationsHow to prepare for kidney function tests, including hydration, protein intake, medication…
- Condition-Specific PanelsPreparing for a Lipid or Cholesterol Test: Fasting and BeyondHow to prepare for a cholesterol and lipid panel, including fasting length, what counts as…
- Condition-Specific PanelsPreparing for a Liver Panel: The Habits That Show Up in Your ResultsHow to prepare for liver function tests, why alcohol and fatty meals matter, which medications…
- Condition-Specific PanelsPreparing for a PSA Test: What Affects Prostate ResultsHow a PSA test works, what can raise or lower a prostate-specific antigen result, and how to…
- Condition-Specific PanelsPreparing for a Testosterone Test: Timing, Sleep, and What to AvoidHow to prepare for a testosterone blood test, including morning timing, sleep, fasting…
- Condition-Specific PanelsPreparing for a Thyroid Panel: Timing, Fasting, and MedicationsHow to prepare for TSH, T4, T3, and thyroid antibody tests, including timing, fasting…
- Condition-Specific PanelsPreparing for a Vitamin B12 Test: Supplements, Fasting, and TimingHow to prepare for a vitamin B12 blood test, including supplement timing, fasting questions…
- Condition-Specific PanelsPreparing for a Vitamin D Test: What Matters and What Does NotHow to prepare for a vitamin D blood test, whether fasting is needed, how supplements affect…
- Condition-Specific PanelsPreparing for an A1c Test: Why This One Is DifferentHow to prepare for a hemoglobin A1c test, whether fasting is needed, what can skew the result…
- Condition-Specific PanelsPreparing for an Allergy Blood Test: What to Know Before You GoHow to prepare for a blood allergy test, whether medications or fasting matter, what the test…
- Condition-Specific PanelsPreparing for an Iron and Ferritin TestHow to prepare for iron and ferritin blood tests, including fasting, supplement timing, and the…
- Condition-Specific PanelsPreparing for an STD Test: Confidential, Simple, and Worth ItHow to prepare for a sexually transmitted infection test, including timing after exposure…
Fasting and Timing
- Fasting and TimingFasting Safely With Diabetes: How to Prepare for a Lab TestHow to fast safely with diabetes for a lab test, including medication questions, low blood…
- Fasting and TimingHow to Fast Before a Blood Test: A Practical Preparation GuideWhat fasting does to blood test results, how long to fast, what you can still drink, and the…
- Fasting and TimingHow to Fast When You Work NightsHow to plan a fasting lab test around night shifts, including where to place the window, how to…
- Fasting and TimingPreparing for a Glucose Test: Fasting, Timing, and What to ExpectHow to get ready for a glucose blood test or glucose tolerance test, including fasting windows…
- Fasting and TimingPreparing for an Oral Glucose Tolerance TestHow to prepare for an oral glucose tolerance test, including the fasting window, the glucose…
- Fasting and TimingThe Best Time of Day for Blood Tests: Timing That Fits the TestWhy morning is often preferred for blood tests, which results depend on time of day, and how to…
- Fasting and TimingWhat Breaks a Fast? Foods, Drinks, and Habits to WatchA clear look at what breaks a fast before a blood test, including foods, drinks, gum, coffee…
- Fasting and TimingWhat Foods Affect Lab Results: Eating Smart Before a TestHow meals and specific foods can shift blood and urine results, which tests are most sensitive…
Sample Collection
- Sample Collection24-Hour Urine Collection: A Step-by-Step Preparation GuideHow to run a 24-hour urine collection correctly, including the discard step, storage, timing…
- Sample CollectionHair Drug Test Preparation: What Affects a Hair SampleHow hair drug testing works, what the collection looks like, which products and treatments can…
- Sample CollectionSaliva and Hormone Test Timing: When to Collect for Meaningful ResultsWhy hormone levels rise and fall through the day, how timing affects saliva and blood hormone…
- Sample CollectionSemen Analysis Preparation: Timing and What to AvoidTiming, abstinence, and transport rules for a semen analysis, plus how to collect and deliver…
- Sample CollectionStool Test Preparation: Getting a Clean, Useful SampleHow to prepare for a stool test, collect a clean sample, avoid common mistakes, and confirm the…
- Sample CollectionUrine Test Preparation: How to Collect a Clean, Useful SamplePractical steps for a routine urinalysis or urine culture, including hygiene, midstream…
Special Populations
- Special PopulationsLab Tests During Pregnancy: How to PrepareHow to prepare for common pregnancy blood and urine tests, including glucose screening…
- Special PopulationsPreparing a Child for a Blood Draw: A Calm, Practical GuideHow to get a child ready for a blood draw with age-appropriate honesty, comfort measures…
- Special PopulationsPreparing a Teenager for a Blood TestHow to help a teenager get ready for a blood test, including needle anxiety, hydration…
- Special PopulationsPreparing an Older Adult for a Blood DrawHow to help an older adult get ready for a blood draw, from hydration and medications to…
Understanding Results
- Understanding ResultsHow Lab Turnaround Times Work: Why Results Take as Long as They DoWhat happens to your sample after the draw, why some results return in hours and others take…
- Understanding ResultsHow to Read a CBC: Hemoglobin, White Cells, and PlateletsHow to read a complete blood count, including hemoglobin, hematocrit, white cells, and…
- Understanding ResultsHow to Read a Lipid Panel: Cholesterol, HDL, LDL, and TriglyceridesA plain-language guide to reading a lipid panel, including total cholesterol, HDL, LDL…
- Understanding ResultsUnderstanding Reference Ranges: What Your Lab Numbers Actually MeanWhat a reference range is, why labs use different ranges, and why a value outside the range is…
- Understanding Resultsmg/dL vs mmol/L: Making Sense of Lab UnitsWhy the same lab result can appear as mg/dL or mmol/L, how to convert between them, and why the…