Pinney et al.  assessed the value of the sFLC response in predicting long-term renal outcome in 923 patients with renal AL amyloidosis. Patients who achieved a greater sFLC response after chemotherapy demonstrated prolonged survival and superior renal outcomes. Patients who achieved more than a 90% FLC response at 6 months had an almost four-fold increase in the chance of renal response (p<0.001) and a lower rate of renal progression (p<0.001) compared with those achieving a FLC response of 0 - 50%. Among 752 patients with a baseline estimated glomerular filtration rate (eGFR) of ≥15 mL/min, those who achieved a 50 to 90% reduction or more than a 90% reduction in dFLC were less likely to experience renal progression requiring dialysis than patients achieving a <50% reduction in dFLC.
Rezk et al.  studied the prognostic value of the response to chemotherapy among 84 patients with AL amyloidosis who presented with advanced CKD (eGFR <20 mL/min). The median time to a composite end point of either death or dialysis was 22.9 months for patients who achieved a dFLC response of ≥90%, compared to 5.3 months among patients who achieved a lesser response (p=0.0001). The dFLC response remained prognostic in the subset of 45/84 patients who had renal amyloidosis without cardiac involvement (time to dialysis was 22.9 months compared to 6.1 months, p<0.008). The authors concluded that an early haematological response is strongly associated with outcome in patients with systemic AL amyloidosis and severe renal impairment.
It should be noted that in cases of renal insufficiency, use of a modified renal reference interval for the κ/λ sFLC ratio may be appropriate. Application of this reference interval has been demonstrated to improve the diagnostic specificity of the sFLC ratio without affecting diagnostic sensitivity in patients with renal impairment (Section 6.3).