Yes, certain tests do need prior fasting. The most common ones are:

Lipid Profile – 12 Hours
Blood Sugar Fasting – 8 Hours
Insulin Fasting – 8 Hours
C Peptide Fasting – 8 Hours
Ultrasound – Whole abdomen, Upper abdomen
TMT
Common analyses which do not require fasting are:-

Kidney Function Test (Urea, Creatinine, Uric Acid, Electrolytes)
Liver Function Test (Bilirubin Total, Direct, SGOT, SGPT, Alkaline Phosphatase, GGTP)
Thyroid Function Test
HbA1c
Urine Culture
ECG
Bone Dexa
Though, it is always advisable to consult the laboratory expert and clarify in advance.

CT scan uses x-rays to produce the images and for patient’s safety, the X-ray dose is kept to minimum for each scan. However, one should avoid having CT scan during pregnancy.

At the time of the scan, an injection of fluid is given into the vein in indivisual’s arm or head. The fluid assists to give clear images. Though the fluid (a dye) is completely free from any side effects, very occasionally, one can have an allergic reaction to the injection of contrast medium. This issue is usually faced by asthma patients. But, a point to note here is that the advantages of having a CT scan outdo the risk of contact to radiation, as the result obtained from the scan is worth it.

In the unlikely event, if a patient faces an allergic reaction, staffs working in the CT scanning are trained to manage the situation. Please note, before CT scan, one is required to fill the form that explains the risk involved in the whole procedure.

General Questions
Q. Is fasting necessary before certain tests? If yes, what are those tests and what should be the ideal duration of fasting?
Yes, certain tests do need prior fasting. The most common ones are:

Lipid Profile – 12 Hours
Blood Sugar Fasting – 8 Hours
Insulin Fasting – 8 Hours
C Peptide Fasting – 8 Hours
Ultrasound – Whole abdomen, Upper abdomen
TMT
Common analyses which do not require fasting are:-

Kidney Function Test (Urea, Creatinine, Uric Acid, Electrolytes)
Liver Function Test (Bilirubin Total, Direct, SGOT, SGPT, Alkaline Phosphatase, GGTP)
Thyroid Function Test
HbA1c
Urine Culture
ECG
Bone Dexa
Though, it is always advisable to consult the laboratory expert and clarify in advance.
CT Scans Questions
Q. Is CT scan safe?
Q. Do I have to do special preparations for my CT scan?
It entirely depends on which part of the body you want to be scanned. Probably you will be asked to remove your cloths and sometimes, all the metal objects like jewellery, and wear a hospital gown instead. In some cases, you may also be asked to drink contrast liquid or have contrast injected into the vein. If your test involves a contrasting medium, your doctor may instruct you to fast for a few hours prior the test.

Talking about medicines, you can have your medicines before the CT scan, until and unless you are a diabetic patient. In that case, you are advised not to take any medicine. However, you should talk to the physicians before the test for the do’s and don’ts.

X-ray is a quick and simple imaging test and you will feel nothing at all during your X-ray.

Well, most bone X-rays require no special preparations. At the max, you will be asked to remove your clothes and sometimes, all the metal objects like jewellery, and wear a hospital gown instead. As that may interfere with the imaging process.

There is so such study till now that states the minimum and maximum number of x-rays in a year or in a lifetime. Although, the amount of radiation that one receives from x-ray is too small to harm anybody.

A mammography, or mammogram, is an X-ray of the breast. It’s a screening tool used to detect and diagnose breast cancer. Together with regular clinical exams and monthly breast self-examinations, mammograms are a key element in the early diagnosis of breast cancer.