53 year old male, previously healthy was diagnosed with precursor B cell ALL-Philadelphia chromosome positive, in May 2014 at a tertiary care oncology centre (detected during evaluation for anaemia.) He was on chemotherapy.
His drug history included:
- 12 doses of intra thecal methotrexate 12mg each=144mg (May to Nov 2014)
- Oral Methotrexate 2.5mg 6 times a week for 6months=150mg (May to Nov 2014)
- Injection Amikacin 2 doses of 900mg each=1.8gm (May 2014)
- Cefeperazone+sulbactam 2 doses 1.5gm each=3gm (May 2014)
- Imatinib mesylate 600mg ODx6 months(May to Nov 2014)
- Vincristine 2mg IV push in June 2014 =4mg
- Mercaptopurine 50mg from July to Oct 2014
- Septran DS twice a day on Saturday and Sunday for 2 weeks only
- Ciprofloxacin 500mg BD
- In addition he received streroids 100mg/day for 1 week in May 2014.
Had presented with complaints of nausea, vomiting, decreased appetite, pedal oedema since 2 months.
Serum creatinine before starting therapy was 1mg/dl and was 1.7mg/dl in July 2014 during routine visits for chemotherapy. This increase was attributed to an episode of gastroenteritis and was treated with hydration+antibiotics. When evaluated for presenting symptoms: serum creatinine was found elevated to 7.9 mg/dl ( 20/11/14) and he was referred to us for further evaluation. Serum calcium, phosphate was normal, and uric acid was 11mg/dl.
On examination he appeared dehydrated, hemodynamically stable, BP 114/70mmHg, systemic exam was unremarkable. Urinalysis showed albumin1+, no blood, no pus cells. Repeated examinations of the urine and phase contrast microscopy showed brown-black crystalline material.
After adequate hydration, kidney function didn’t improve and a kidney biopsy was done as below:
Currently his serum creatinine is static at 4.8-5mg/dl for last two weekly follow ups. The patient has been in complete morphologic and cytogenetic remission since July 2014.
Which of the following is least likely to be the cause of AKI in this patient?