Male adolescent: fasting low alkaline phosphatase blood result 85 iu/l l (normal range 100-450 iu/l l).does this indicate malnutrition(vitamin/mineral malabsorption); all other results in hepatic func panel normal range. what does this indicate?

Hard to say: Since many other labs would list the low end of normal as low as 30 IU/L it is hard to comment on a single lab value without context. Low values are associated with poor nutrition & a number of medical conditions. Without a full review of history, exam and review of all testing it is hart to decide if this is a problem or not.

Need more info: All laboratory results need to be interpreted in the clinical context and the doctor who ordered the tests is usually in the best position to do that. Talk to the doctor who ordered the tests. Having said that, if you are maintaining normal weight, this lab value is not a cause for concern. Wish you good health!