Why would low copper levels cause low ceruloplasmin levels?

Stabilized by copper: In this case, the protein that becomes ceruloplasmin (called apoceruloplasmin) is more stable in the presence of copper. So low copper levels will cause a faster degradation of the protein that otherwise becomes ceruloplasmin. Additionally, unlike some proteins, there is no increased production of ceruloplasmin when copper levels are low, .