The purpose of this blood serum test is to help detect and evaluate treatment of acute hepatic disease, especially hepatitis, and cirrhosis without jaundice. To help distinguish between mytyocardial (heart) and liver tissue damage (used with the AST enzyme test). Also to assess hepatotoxicity of some drugs.
The average wingspan for an NBA player (even normal 6'0 guys) is +4 inches. I think that around your height thing is just an estimate. For the general population, the average might be +2 inches.
Averages vary by racial and ethnic groups. For example, the average adult non-Hispanic white male is 5 feet 9.8 inches tall and the average adult non-Hispanic black male is 5 feet 9.5 inches tall. The average height of adult Hispanic males is 5 feet 7.1 inches. Among adult Mexican American males -- who are also included in the category of Hispanic -- the average height is 5 feet 6.9 inches. Height also varies by country. Here are a list of 15 countries and how they stack up with the US.