**Question:** What is the standard dose of PPD for Mantoux test?

**Core Concept:** The Mantoux test, also known as the purified protein derivative (PPD) test, is a skin test used to diagnose tuberculosis infection or reactivation of the disease. The test involves the injection of PPD into the skin to assess the immune response.

**Why the Correct Answer is Right:** The standard dose of PPD for the Mantoux test depends on the age and body surface area (BSA) of the patient. For children under 5 years old, the recommended dose is 1 tuberculin units (TU). For children aged 5-18, the dose is 1-5 TU based on their estimated BSA. For adults, the standard dose is 5 TU.

**Why Each Wrong Option is Incorrect:**

A. This option suggests using 0.1 ml of PPD for the test, which is too low a dose and might not provide a reliable result.
B. This option mentions a dose of 5 TU for children under 5 years old, which is incorrect as the standard dose is 1 TU.
C. This option suggests using 10 TU for children aged 5-18 years, which is too high a dose and can cause skin reactions unrelated to tuberculosis infection.
D. This option recommends using 5 TU for adults, which is the correct answer but still needs to be clarified with respect to age and BSA.

**Clinical Pearl:** Dosage adjustments are crucial to ensure accurate results in the Mantoux test. The correct dose depends on the patient's age and body surface area. This ensures the test is both safe and reliable in diagnosing tuberculosis infection.

**Correct Answer:** For adults, the standard dose of PPD for the Mantoux test is 5 tuberculin units (TU).