Cases from the Brigham and Women's Hospital: A lupus pregnancy

You are consulted on a  26-year old woman who is G7,P, who has been admitted to the obstetric ward in the 23rd week of gestation. She is hypertensive and has mild edema. Her 24 hour urine protein excretion is approximately 3 grams, serum creatinine is 1.5 mg/dL. Complements: C3 49, CH50 <2, C4 <10, and anti ds DNA antibody 230. Jer urinalysis shows: 4+ albumin, large blood, dysmorphic RBCs and RBC casts.

The patient has a history of SLE dating back to April 2002. Her prior history is rather vague: several months of diffuse joint aches. In January 2007 she saw a nephrologist. The serum creatinine at the time was 0.6 mg/dL. A 24h urine protein excretion was 300 mg.

On admission she is treated with steroids (methylprednisone 250 mg IV for the first day  and then 500 mg  on day 2 and 3 followed 5 days later with another steroid pulse (1 g/day IV methyl prednisone for 3 consecutive days). In addition, azathioprine at a dose of 1.5 mg/Kg is started and increased to 2 mg/kg. Her serum creatinine continues to rise and 5 days following admission her serum creatinine is 3.1 mg/dL. A renal biopsy is performed (click over slides to enlarge). What do you recommend?