Monday, May 3, 2010

Isolated microscopic hematuria

We have had a rush of patients with isolated hematuria in my clinic recently. The question that occupies so much precious time of the nephrologist reared it's head....... 'what are the indications for a renal biopsy'.

Isolated persistent glomerular hematuria (with dysmorphia) without proteinuria, hypertension or reduced GFR is one of 4 things according to several studies [Caldas et al (1990) Lab Ix; 62:15A. Tiebosch et al (1989) NEJM;320:140]. IgA nephropathy, Alport's Syndrome, Thin Basement Membrane disease or mild glomerulonephritis. Approximately 5% have other diagnoses and a number have a normal biopsy.

Most of these patients have a long term benign course. However many patients with Alport's disease develop progressive renal disease, as do a number of patients with this form of IgA nephropathy. Although thin basement membrane disease is said to be benign, it is not exclusively so and many patient have mutations in Col4a3, Col4a4 genes, similar to Alport patients.

In a pediatric study of Physicians deciding whether to biopsy children for isolated hematuria, only 5% said they would. Further in Pediatric studies where biopsies were performed, only 1 in 39 biopsies for isolated hematuria resulted in a change in management.

It is not always possible from family history to make the diagnosis. However, TBMD is frequently inherited in an AD manner, while Alports syndrome is both autosomal recessive and X-linked (rarely AD). Fewer than 10% of IgA nephropathy patients have an inherited form.

The presence of sterile pyuria might also point to a nephrotoxic cause or a component of interstitial disease and might be taken as a sign of underlying disease activity.

So for patients with isolated persistent hematuria and no clear diagnosis one can either monitor the patients regularly for changes in renal presentation or perform a biopsy.

I would favor performing a renal biopsy only if:

  • patient requests for certainty/inform family members/diagnostic curiosity
  • Any suggestion from H & P that this might be the early stages of a non-benign disease
  • Other atypical features including pyuria.


abraham said...

it is also necessary to check up on other systemic manifestations ( deafness , skeletal signs , eye involvement ... )

tin said...

is an allergic cause possble?

Blood in the urine said...

Reiterate that getting effective treatments should be a priority for people who are suffering from hematuria related diseases. This is because this diseases can truly snowball into other complication when not treated promptly.