The epiphysis, or growing area, of long bones usually closes by age 16 or so. An increase in circulating growth hormone (gh) would have no effect on these bones and an increase in height would be very unlikely. Normal serum levels of growth hormone is 3-5 ng/ml. People with acromegaly (a disease characterized by abnormal growth of soft tissues due to increased gh caused by a pituitary tumor) have levels around 10 ng/ml for long periods of time. You’d have to take a very, very large dose of l-arginine to raise your hg level to 6 ng/ml and it wouldn’t last long enough to make much difference.
You might want to read this.
If you’re concerned with a reduction in your height, that seems to normally occur as we age and is generally due to a shortening of the spine. I guess good posture and an attention to your overall body condition may help, but you probably won’t have to worry about that for quite some time.