What other labs can be ordered when a ch50 is high? c3 and c4 are normal. my doctor is trying to figure out the reason for a high ch50. thank you?

https://www.medicalhealthtests.com/blood-tests/complement-ch50.html Would check C1q and do autoimmune work up including CBC, CMP, thyroid studies and antibodies, sed rate CRP, ANA, DS DNA for starters. Would also assess for possible infection ( including chronic prostatitis) and check CXR( chest /lungmass/lesions), possible thyroid ultrasound. Would repeat CH50 in 1 month to see if changed