Lab draws off PICC

You may want to assess the gauge and size of all blood collection devices (especially if it's a new shipment of equipment) used and the lumen of PICC, presence of any extension sets, etc... make sure they are large bore. For technique, slower draw more likely to keep cells intact. Hope this helps :)

There are a lot of potential causes for hemolysis, so it's impossible to say what is causing this in your particular case. My suggestion is to review the literature on proper blood collection techniques and practice it to the letter.

Some common causes of hemolysis:

Too much pressure applied when pulling back the plunger on the syringe

Applying pressure to the syringe to push the sample into the tube

A loose connection between add-on devices and the catheter hub, allowing oxygen to enter the sample

Shaking the tubes too roughly; gently invert tubes the recommended amount of times for each type of tube

If blood does not return easily without additional pull the line needs to be declotted once it has been checked for position and kinking.

Forced blood drawing does hemolyze cells which releases intercellular folks like Mr K+ into the Serum count.