Taking coffee into the fasting window
The most common fasting error in the UAE is the 6am black coffee before a 7am lipid draw. Caffeine shifts glucose and fat metabolism enough to matter, and 'but it has no calories' does not rescue the sample. Water only, then coffee the second the plaster is on.
Retesting vitamin D three weeks into supplements
Vitamin D moves slowly; levels take roughly three months on a steady dose to reach their new plateau. Testing early shows a half-finished number, prompts an unnecessary dose change, and wastes AED 180–350. Set a calendar reminder for twelve weeks and resist the urge.
Hopping between labs and comparing the numbers
Different laboratories use different assay methods and reference ranges, so a small shift between two labs may be methodology, not biology. For anything you track over time — HbA1c, lipids, thyroid, ferritin — keep the same vendor and lab, and let the trend do the talking.