Arrange following according to increasing order of their total body water as percentage of body weight 1. 6 month baby 2. neonate 3. young female 4. young male
**Core Concept**
Total body water (TBW) is a critical component of a person's overall health, and its percentage varies across different age groups and genders. The percentage of TBW is influenced by the distribution of body water among various compartments, including intracellular, extracellular, and intravascular spaces.
**Why the Correct Answer is Right**
In neonates and young infants, the percentage of TBW is higher due to a larger extracellular fluid compartment. As age increases, the percentage of TBW decreases due to the maturation of the kidneys and the shift of water from the extracellular to the intracellular compartment. In adults, the percentage of TBW is lower in males compared to females, particularly in the younger age group. This is because males have a higher muscle mass and a lower body fat percentage compared to females.
* **Option A:** 6 month baby - The percentage of TBW in a 6-month-old baby is higher (around 70-75%) compared to neonates and young adults due to a larger extracellular fluid compartment.
* **Option B:** Neonate - Neonates have the highest percentage of TBW (around 80-85%) due to a larger extracellular fluid compartment and a higher proportion of body water in the extracellular space.
* **Option C:** Young female - In young females, the percentage of TBW is higher (around 55-60%) compared to young males due to a higher body fat percentage and a lower muscle mass.
* **Option D:** Young male - Young males have the lowest percentage of TBW (around 50-55%) due to a higher muscle mass and a lower body fat percentage.
**Clinical Pearl / High-Yield Fact**
The percentage of TBW decreases with age, and it is higher in females compared to males, particularly in the younger age group. This is due to the differences in body composition, with females having a higher body fat percentage and a lower muscle mass compared to males.
**Correct Answer:** B. Neonate