How to prepare for a blood test in Dubai.

Do I need to fast for a blood test?

Fasting means no food or calorie-containing drinks for a set period — usually 8–12 hours — with plain water allowed. It is only useful for a small number of markers where recent food would change the result. For most patients, the answer is no.

• · Fasting usually required: Fasting glucose, lipid profile (total cholesterol, LDL, HDL, triglycerides), fasting insulin, HOMA-IR, oral glucose tolerance test.
• · Fasting not required: HbA1c, thyroid function (TSH, Free T4, Free T3), vitamin D, vitamin B12, folate, ferritin, iron studies, full blood count, CRP, liver function, kidney function, PSA.
• · Depends on the panel: If a lipid or glucose test is bundled into your health check, the whole visit becomes a fasting visit. Our team confirms this at booking.

Water, coffee, tea and smoking before a blood test

Plain water is encouraged during any fast — dehydration makes the vein harder to find and can artificially raise haemoglobin, creatinine and calcium. Coffee, tea (even without milk or sugar), energy drinks and juice all break a fast for lipid or glucose testing. Avoid smoking or vaping in the 60 minutes before a blood draw — nicotine transiently raises cortisol, glucose and some lipids.

Should I take my medicine before the test?

Keep taking your prescribed medicine as normal unless your doctor has specifically told you to hold a dose. Do not stop blood pressure, thyroid, statin, insulin or diabetes medicine on your own — the risk of stopping usually outweighs any small effect on the result. If a medicine may interfere with a specific test (for example levothyroxine timing for TSH, or steroids before a cortisol test) your Aafiyah GP will give you a written plan before the visit.

Biotin and supplements

Biotin (vitamin B7, often 5,000–10,000 mcg in hair, skin and nail supplements) interferes with many laboratory immunoassays and can produce falsely high or falsely low results for thyroid hormones, troponin, PSA, hCG, cortisol and vitamin D. Stop biotin-containing supplements at least 48 hours — ideally 72 hours — before testing. Ordinary multivitamins with 30–100 mcg biotin are generally safe but let us know what you take.

Exercise, alcohol and sleep

Avoid intense exercise for 24 hours before a blood test — heavy workouts transiently raise creatine kinase, AST, ALT, white cell count and creatinine, and can shift a result out of range for no clinical reason. Avoid alcohol for 24 hours before liver, lipid and uric acid testing. Poor sleep raises cortisol and glucose, so try to test after a normal night rather than after a long-haul flight or night shift where possible.

Testosterone and hormone timing

Total testosterone should be measured between 07:00 and 10:00 — levels are 20–30% higher in the morning and a low afternoon reading is not reliable. Prolactin is best drawn 1–2 hours after waking, not immediately after a stressful commute. In women, day 2–5 of the menstrual cycle is standard for FSH, LH and oestradiol when assessing ovarian reserve, while progesterone is typically drawn 7 days before the expected next period. If cycles are irregular, we take the sample when clinically useful and interpret it in context.

Illness, dehydration and pregnancy

A recent viral infection can raise CRP, ferritin and white cells and lower haemoglobin for 2–3 weeks — routine screening blood is best deferred if you are actively unwell. Severe dehydration (long flights, gastro, heat exhaustion) concentrates the blood and can push haemoglobin, calcium, creatinine and albumin above the reference range. Pregnancy shifts reference ranges for thyroid, iron, D-dimer and many other markers — always tell us if you are or may be pregnant so we interpret results against pregnancy-specific ranges.

Children, needle anxiety and the home visit

For children under 12 we bring a smaller butterfly needle, apply topical numbing cream 30 minutes before, and let a parent stay in the room. For adults with needle phobia we can draw lying down and use distraction techniques — tell us at booking and we will allow extra time. Home visits work exactly the same clinically as clinic draws: same vacutainers, same DHA-accredited lab, same turnaround.

How long do results take and who explains them?

Most routine blood results (CBC, lipids, HbA1c, kidney, liver, vitamin D, thyroid) are back within 24 hours. Specialist hormone, allergy and tumour-marker panels take 2–5 working days. Every result is reviewed by a British-trained GP who calls you personally with a plain-English explanation and written plan — you never receive a raw PDF with no interpretation.