What does a high TSH level mean?
TSH (Thyroid Stimulating Hormone) is the signal your pituitary gland sends to tell your thyroid how hard to work. Most labs use a reference range of about 0.4 to 4.0 mIU/L. A TSH above that range usually means your thyroid is underactive (hypothyroidism). A single elevated TSH is not a diagnosis on its own; thyroid levels shift with illness, time of day, and even recent biotin supplements.
What does a low TSH level mean?
A TSH below the reference range (under roughly 0.4 mIU/L) usually points to an overactive thyroid (hyperthyroidism). Common causes include Graves' disease, thyroid nodules, or taking slightly too much thyroid replacement medication.
How do I read my blood test results?
Every lab report has the same basic columns: the test name, your result, the units, and the reference range. Compare your result to the range on the same row. Results outside the range are usually flagged with an H (high) or L (low). A flagged value is a reason to ask a question, not a reason to panic.
What is the difference between a normal and an optimal lab range?
A normal (reference) range is built from a statistical spread of the general population. An optimal range is narrower and reflects where research suggests you have the lowest health risk. Vitamin D is a good example: a level of 31 ng/mL may be flagged normal, but many clinicians consider 40 to 60 ng/mL optimal.
What does a CBC blood test measure?
A CBC (Complete Blood Count) measures red blood cells and hemoglobin, white blood cells, and platelets. It gives a broad snapshot of your overall health and is often the first test ordered when something feels off.
What does high LDL cholesterol mean?
LDL is often called bad cholesterol because, in excess, it contributes to plaque buildup in your arteries. For most adults an LDL under 100 mg/dL is considered optimal. A high LDL is one piece of your cardiovascular risk picture.
Why is Vitamin D important and what does a low level mean?
Vitamin D helps your body absorb calcium, supports bone strength, and plays a role in immune function and mood. Levels below 20 ng/mL are generally considered deficient. Many clinicians consider 40 to 60 ng/mL optimal.
What does a low ferritin level mean?
Ferritin is your body's stored iron — the best early warning sign of iron deficiency, often before a CBC shows anemia. A low ferritin (commonly under 30 ng/mL) can cause fatigue, hair thinning, brittle nails, and restless legs.
What is HbA1c and what is a normal level?
HbA1c reflects your average blood sugar over the past two to three months. Below 5.7 percent is considered normal, 5.7 to 6.4 percent is the prediabetes range, and 6.5 percent or higher on two occasions supports a diabetes diagnosis.
What does a fasting glucose test tell me?
A fasting glucose measures your blood sugar after at least eight hours without food. A normal fasting glucose is 70 to 99 mg/dL, 100 to 125 indicates prediabetes, and 126 or higher on two occasions supports a diabetes diagnosis.
Do I need to fast before a blood test?
It depends on the test. Fasting is typically required for fasting glucose and a lipid panel. Many other tests — including CBC, thyroid panel, and HbA1c — do not require fasting.
Why should I be hydrated before a blood draw?
When you are dehydrated, the liquid portion of your blood shrinks, which concentrates everything in it and can artificially raise results like hemoglobin and creatinine. Being well hydrated keeps values accurate and makes the draw more comfortable.
Can supplements affect my lab results?
Yes — especially biotin (Vitamin B7), found in many hair, skin, and nail supplements. High-dose biotin can interfere with thyroid tests and troponin, sometimes producing falsely high or low results. Stop biotin three to five days before blood work.
What questions should I ask my doctor about my lab results?
Ask: Which results are outside range and how far? Are any worth rechecking before we act? What could be causing this? Should we test anything else? How soon should I retest? Writing these down before your appointment helps you leave with a plan.
What is the difference between Free T4 and TSH?
TSH is the signal from your pituitary telling your thyroid how hard to work; Free T4 is the actual thyroid hormone in your blood. Think of TSH as the thermostat setting and Free T4 as the room temperature.
Why are some lab values flagged but my doctor is not worried?
A flag simply means a result fell outside the statistical reference range — it does not measure severity. Many values sit just outside the range for harmless reasons. Your doctor reads the flag in the context of your history, symptoms, and trends over time.
How often should I get routine blood work?
For most healthy adults, a basic set of labs once a year is a reasonable baseline — typically a CBC, metabolic panel, and lipid panel, with thyroid and Vitamin D added based on symptoms or risk.
Is AskSonya.ai a substitute for seeing my doctor?
No. AskSonya.ai is an educational health literacy platform — its purpose is to help you understand your lab results and walk into appointments better prepared, not to diagnose or treat anything. Always consult a qualified healthcare professional for medical decisions.