It depends on the lab. Red, speckled, yellow...
A lavender-top tube should be used to collect a fasting prolactin level sample.
A lavender top tube is typically used to collect blood samples for homocysteine level analysis.
serum,tiger tube
I would use the semi-colored tube.
green
a lavender top tube
red
red
blue
A green-top vacutainer tube (or sometimes a pink-top tube) is typically used for collecting blood samples for lithium level testing. The green tube usually contains lithium heparin as an anticoagulant for plasma testing, while the pink tube may contain EDTA if plasma separation is not required. The specific tube color may vary depending on the lab's protocols, so it's best to confirm with the lab where the test will be performed.
He should follow his doctor's instructions. The answer will depend in part on his testosterone level testing.
Light blue