55-year-old woman was admitted to Nephrology Unit because of acute renal failure. About two weeks prior to admission, while on overseas trip, the patient presented to the ER with fever and productive cough. Chest-X-Ray revealed pneumonia. She was treated with an unspecified cephalosporin for one week. A week later, because of persistent weakness, the patient returned to Italy and was admitted the following evening.

Medical history:  
None

Physical Exam:
BP, 130/80; pulse 78/min; Temperature, 36 C;
Cardiac auscultation within normal limits
Chest clear
Skin without rash
The remainder of the examination was unremarkable

Laboratory and other data:
Hb 12 mg/dL, WBC 7000/mm3, LDH 230 U/L,
BUN 70 mg/dL, serum creatinine 4.5 mg/dL,
Na 140 mEq/l, K 4 mEq/L, Uric acid 3.5 mg/dL, P 2.4 mg/dL, Ca 8.5 mg/dL,
Liver function tests normal
Urinalysis: microscopic haematuria (+++), no glucosuria, proteinuria was 2.5 g/L with albuminuria of 0.4 g/L.
Her renal ultrasound was normal.

Short term follow up:
In follow up, further laboratory workup was done: Serum lambda free light chain (FLC) levels were raised (1200 mg/l) with a kappa:lambda ratio of <0.02. Serum immunoglobulins were within normal limits. Bone marrow examination showed a hypercellular marrow with 10% CD138-positive plasma cells with a lambda restriction. A skeletal survey was unremarkable. Urinary lambda levels of 1.5 g/l.
Steroid treatment was initiated with prednisone at 1 mg/kg/day. The patient’s renal function rapidly improved. The patient was discharged.
About two weeks later, her serum creatinine level was 2 mg/dL.
At a subsequent outpatient clinic, two months later, her serum creatinine was stable at 1.4 mg/dL, 24h-proteinuria was 2.5 g/day (albuminuria 0.4 g/day, urinary lambda 1.8 g/day).
Serum Uric acid was 3 mg/dL, serum Ca 9 mg/dL, serum P 2.1 mg/dL, Hb 14 g/dL, SFLC ratio k/l 0.01.
The urinary excretional fraction of Uric acid and Phosphate were both elevated.
No glucosuria, urinary pH 5.