A 38 year old woman who has been on anti-retroviral therapy for 3 years is found to have a creatinine of 230 micromol/l (2.6 mg/dl). She is taking Tenofivir, Efavirenz and cotrimoxazole and has been compliant with therapy. She complains of recurrent dysuria and frequency, as well as intermittent fevers which do not always seem related to urinary symptoms. She describes some vaginal discharge.
On examination she is thin but not emaciated. She has no oedema. Her pulse is 64, blood pressure 110/60, chest is clear, cardiovascular system normal. She has mild non-specific abdominal tenderness but no masses.
Urine dipstick is positive for nitrites and leucocytes, blood 1+.
What type of disease process do you suspect? What further features or investigations would you immediately seek?
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She has marked renal impairment; that creatinine corresponds to an eGFR of about 26. She already has possible explanations for renal disease from her diagnosis of HIV and the fact that she is on anti-HIV drugs, many of which have renal side effects, including crystallization, interstitial nephritis, tubular injury.
A key observation is the bland urinary sediment, showing little protein or blood, which essentially rules out severe glomerular pathology. HIV nephropathy is a glomerulopathy, so it is an unlikely explanation. Using the pre-renal/renal/post-renal algorithm, this makes you home in on
- Pre-renal causes. She doesn’t sound very dehydrated, but pre-renal causes include arterial and small vessel disease; for instance thrombotic microangiopathy can occur in HIV.
- Interstitial or tubular causes (drugs particularly likely to be implicated; tenofivir is associated with tubular injury)
The key investigation in any patient with renal failure and urinary symptoms is renal imaging. Ultrasound is quick, non-invasive, risk-free, and almost always first choice; it should be part of the investigation of almost any patient with unexplained new severe CKD. It showed bilateral hydroureter and hydronephrosis without distention of the bladder.
Hope you had also written that vaginal examination is one of the things that you must do here. She had advanced cervical cancer involving both ureters.
She also had a CD4 count of 93 despite her anti-HIV therapy, with PCR showing 5,000 copies per ml, suggesting anti-retroviral failure. In a well-resourced setting you would consider testing for drug resistance.
Thanks to Fran Th’ng and Gavin Dreyer for this case.