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Most vitamin B12 blood tests don’t need fasting, but fasting is common when your order includes other blood tests.

No, fasting isn’t required for a vitamin D blood test unless it’s paired with other labs that need fasting.

No, fasting isn’t needed for TSH, T3, and T4 tests; med timing and biotin are the prep steps that change results.

Yes, “do i need to fast for a stress test?” usually means no food 2–4 hours and no caffeine 12–24 hours, unless told otherwise.

Yes, you’ll need fasting before wisdom teeth extraction with IV sedation or general anesthesia; local numbing alone usually allows a light meal.

No, most calcium score tests don’t need fasting, but skip caffeine and nicotine for a few hours if your center asks.

No, you don’t need to fast before a mammogram; eat and take meds as usual unless your clinic gave different instructions.

Most prenatal blood work doesn’t need fasting, but some glucose or cholesterol tests do, so follow your lab order.

No, fasting before an MRI scan often isn’t needed unless you’re having sedation or certain belly-focused MRI exams.

No, an SGPT (ALT) test alone seldom needs fasting, but you may be told to fast 8–12 hours if it’s part of a panel.