I'm not Sarita, but I thought I might jump in here because I wrote a report about triglycerides a few years ago. I'm wondering if you might have one of the familial lipid disorders. Even your normal level (around 200) is considered high by US guidelines (normal is under 150, up to 199 is considered borderline high, and anything 200 or over is unequivocally high). I know you you don't know of a family history of this, but maybe some relative did pass it on to you. The hereditary conditions that can cause high triglycerides are all a bit of a mouthful, but you could google each if you are curious: familial chylomicronemia syndrome, familial hypertriglyceridemia with chylomicronemia, familial dysbtalipoproteinemia, familial combined hyperlipidemia, familial hypertriglyceridemia, and hepatic lipase deficiency.
Kidney disease can also cause high levels of triglycerides. This is not something I know anything about, barring the fact that it is a known risk factor, but if the genetic conditions are definitely ruled out, it is something you might want to consider seriously. Any chance of getting another nephrology consult?
Hope things start looking better soon.
PS: Sorry for the weird font changes. This message board does not play nicely with my voice-recognition software.