The following collection instructions are intended to help you collect the correct specimen for the test your clinician has requested. First read the instructions carefully, make sure you are prepared, and then follow each of the steps to ensure proper collection.
NOTE: You may be required to fast before having a blood test. This is because certain test values, for example blood sugar (glucose) change following the digestion of food.
Non-fasting specimens are acceptable for most situation requiring analysis of blood triglyceride levels, however some exceptions apply. Your doctor will determine if fasting is required for you.
These tests typically require fasting:
- Fasting blood glucose
- Lipid profile
- Basic or comprehensive metabolic panel is often part of a routine physical. The tests check your blood sugar, electrolyte and fluid balance, and kidney function. The comprehensive test checks your liver function, too.
- Renal function panel
- Vitamin B12 test
- Iron tests
- Gamma-glutamyl transferase (GGT)
- TSH : A TSH test is done to find out if your thyroid gland is working properly. It’s best to do this in the morning as your TSH levels can fluctuate throughout the day.
If you are asked to fast for your test do not eat anything for a minimum of:
- 8 hours for a fasting glucose/GTT or
- 12 hours for lipid assessment test before you go the laboratory to have your blood taken, if fasting is required.
Do not drink any juice, tea or coffee. You are allowed to drink water. Do not smoke, chew gum, or exercise. These activities may stimulate the digestive system and alter test results. After the specimen is collected, you may resume your normal diet.
QUESTIONS & ANSWERS:
Q. Why do I have to be fasting?
A. Some test values change following the digestion of food. For example, if you eat lots of sugar, your blood
sugar will be high. When you are fasting, we get a base result that can be compared over time.
Q. May I drink water?
Yes, you can drink water but not other kinds of drinks.
Q. Should I continue to take my medications?
Yes, unless your doctor tells you not to.
Q. May I drink juice?
No, just water.
Q. May I drink coffee?
No, not even black without sugar, and the same goes for tea. You can drink water.
Q. May I chew gum?
No, not even sugarless. Gum stimulates your digestive system and can alter the test results.
Q. May I smoke?
No, smoking can affect the test results.
Q. May I do my exercise routine?
No, exercise can also affect test results.
Most people find it convenient to stop eating and drinking after 8:00 PM and to arrive at the laboratory early the next morning.