Final answer:
Pediatric drug doses are commonly calculated based on body weight to ensure that the child receives an appropriate dose. For older children and adults, there are standard doses, and factors like liver or kidney function can affect dosing. Height and weight are used to monitor child development, and the BMI has limitations when applied to children.
Step-by-step explanation:
Pediatric drug doses are most accurately calculated based on body weight, especially in younger children. This method helps ensure that the child receives a dose that is proportional to their physical size.
For older children and adults, doses may be standardized, though there's an ongoing debate about the relevance of weight-based dosing in adults due to the wide range of body sizes.
Other factors, such as body surface area, age, and height, can also play roles in specific clinical scenarios, but body weight is the primary criterion for pediatric dosing.
In cases where liver or kidney dysfunction is present, additional adjustments may be required as these conditions can influence drug metabolism and clearance, and consequently, drug levels in the body.
In situations where growth and development are monitored - using height and weight - calculations like the z-score can be employed to evaluate a child's development compared to a reference population. A z-score indicates how many standard deviations a value is from the mean.
For instance, a weight of 11 kg would have a z-score of 1 ((11-10.2)/0.8), indicating that it is one standard deviation above the mean weight for girls of that height and age. A weight of 7.9 kg would have a z-score of -2.875 ((7.9-10.2)/0.8), which is almost three standard deviations below the mean, potentially a cause for concern.
Finally, it's important to consider Body Mass Index (BMI), though it has limitations in children and adolescents due to their growth. Conventional BMI calculation may not be optimal for this population, and alternative methods like BMI adjusted for height cubed are being explored.
It's also critical to understand that obesity in children, defined as a body weight at least 20 percent higher than healthy weight for their height, is a distressing trend with negative health implications.