My question is for hematology, my kappa free light chain is 27.3 at what point it will start affecting my kidneys?

You probably have the condition MGUS (monoclonal gammopathy of undetermined significance). I wonder if you know the ratio of kappa and lambda light chains. If free light chain is detected in you urine, renal function has been affected because the light chain causes renal damage when the filtered light chain is absorbed and we use the term monoclonal gammopathy of renal significance.

Your kidney may already be affected. It would be prudent to consult a nephrologist for an evaluation. A monoclonal gammopathy of undetermined significance can also be monoclonal gammopathy of renal significance. You may need care from both a hematologist/oncologist and a nephrologist. Wish you good health!