No fasting required. The check-up is a basic check to see if they are in good health. Any visible signs of illness, listen to their heart, blood pressure, listen to their lungs, etc. The doctor should ask about any known illnesses and what medication they are taking. You can write down all of the medication beforehand and bring the list or just bring the medication if you prefer. They will do a blood test to look at basic things like their white and red blood cells, kidney and liver function, blood sugar and usually testing for some transmittable diseases like HIV,hepatitis, etc. In most countries parents will also be sent for a chest x-ray to see if there is any signs of TB. X-ray would also show other lung diseases. If there is scarring on the lungs you would be asked to give a sputum sample and then repeat the x-ray in 3 months to make sure nothing has changed or gotten worse. The sample will also see if any bacteria or fungus grows in the sputum. This is mostly to look for TB.