Check for obstruction..

Pearl:  In a patient with an elevated creatinine, check the urine for protein.  The urine needs to be adequately concentrated (look for a specific gravity of 1.020, or at least 1.015).  Often, if there's a rise in the serum creatinine without protein in the urine the diagnosis turns out to be obstructive uropathy.

• Follow up with a renal ultrasound with post void residual (men) or a bladder scan with post void residual.  The renal ultrasound may demonstrate hydronephrosis or an underlying cause for obstruction.

Case:  A 24 y/o female with a PMH of IDDM since age 9 presents to the clinic with a creatinine of 2.4.  She's had a few days of vague abdominal pain and visited a local ED three days ago and was given fluids.  Her PCP called in antibiotics for a UTI on the previous day although there is currently no evidence of infection.  The patient denies nocturia but admits to urgency.  Upon further questioning, this very anxious and clearly uncomfortable young lady states that she feels like she needs to urinate but can't.  She was unable to give a urine sample in the office.  The patient was sent to the ED for a bladder scan with post void residual.  This demonstrate 1000cc with 999cc residual.  The patient was referred to urology and seen in the clinic the next day for further nephrologic evaluation.

• This patient's cause likely due to her diabetes.  The patient did have a history of diabetic neuropathy and another complication of diabetes is neurological involvement of the detrusor muscle of the bladder.