Prognostic value of urinary protein in primary systemic amyloidosis (AL)

In 153 patients with biopsy-proven primary systemic amyloidosis (AL), serum creatine level correlated with median survival (creatinine ≤ 115 μmol/L [1.3 mg/dL], 25.6 months; creatinine > 115 μmol/L [1.3 mg/dL], 14.9 months; P = 0.007). The 24-hour urine total protein excretion was not correlated with survival. Patients who excreted monoclonal lambda light chains in the urine had an inferior survival (12 months) compared with those with kappa (30 months) or no monoclonal protein (35 months) in the urine (P = 0.01). The presence of lambda monoclonal protein was not associated with a higher median creatinine level. A monoclonal protein was detected in the urine in 76% of patients; when patients with more than 1 g of protein in the urine were studied, however, a monoclonal protein was detectable in 86%. The overall kappa-lambda ratio was 1:2.56, but as the urinary protein loss increased, the kappa-lambda ratio shifted to 1:4.7 for those with more than 3 g of protein in the urine.