Kasus: High creatinin and Urea after back pain medication

A 46-year-old Caucasian male (CM) with chronic back pain takes large doses of over-the-counter pain medications. He works 12-hour night shifts and has to take 15-20 pills, especially Motrin (ibuprofen) and Aleve (naproxen), during the shift and about the same amount during the day in order to "function."

He went to the ER today because of his back pain. CBC and BMP are ordered.

Past medical history (PMH)Back pain.

Medications
Motrin (ibuprofen), Aleve (naproxen), Advil (ibuprofen), Ultram (tramadol), Tylenol (acetaminophen).

Physical examination
Limited range of motion (ROM) of lower back, otherwise unremarkable.

Laboratory results
BMP showed a creatinine of 3.3 mg/dL, BUN 25 mg/dL. CBC was normal.

The patient had a normal CBC and BMP one month ago.

Author: V. Dimov, M.D.
Reviewer: S. Noor, M.D.

What is the most likely diagnosis?
What tests would your order?