Final answer:
The preferred testing modality in children is the TST (PPD), which is used to assess for tuberculosis exposure.
Step-by-step explanation:
The preferred testing modality in children is the TST (PPD), which is used to assess for tuberculosis exposure. This test measures the response of the immune system to proteins derived from the bacteria that cause tuberculosis. By injecting a small amount of the purified protein derivative (PPD) into the skin, healthcare providers can evaluate if a person has been exposed to the bacteria that causes tuberculosis.
Other testing modalities mentioned in the question, such as glucose tolerance tests (GTT) and liver function tests (LFTs), are not typically used to screen for diabetes or evaluate liver function in children.