Testing serum free light chains/protein electrophoresis and calcium?

[suemacke]

I've been following postings for a few months but haven't posted because I have no official diagnosis. I had my first appointment with a nephrologist who said I don't have any of the common causes for kidney damage so he sent me for more tests to rule out underlying issues. Along with the 24-hr urine collection for creatinine & protein, ultrasound, he added serum free light chains/protein electrophoresis and calcium to the blood work and/or urine collection. From those more experienced with these tests, I'm wondering if these are part of the regular testing for kidney disease and if you know what they are for? Google searching turns up multiple myeloma which does concern me -- though I understand testing is to rule things out... still it would be nice to hear it's just normal testing since I don't go back for two months. So any additional info you have would be helpful.

About me: I'm 48 year-old female with an eGFR of 53, hematuria, creatinine 1.2, low to normal blood pressure, several autoimmune diseases (celiac, pernicious anemia, intermittent ovarian failure). I suspect the kidney damage is related to my autoimmune issues since they've caused secondary issues well before my time, including being diagnosed with osteoporosis and going into menopause in my late 30s. Thanks in advance for you help.