Richard is an advanced trainee in nephrology and general medicine. He completed his basic training in Tauranga Hospital and his advanced training in nephrology at Waikato, Auckland and Middlemore hospitals. He is currently finishing the general medicine component of his training and ultimately hopes to move back to the Bay of Plenty as a consultant to help run a growing renal service.
Utility Of Kidney Biopsy In Patients With Significant Proteinuria In The Non-Nephrotic Range
Richard Germann, Waikato Hospital, Hamilton, New Zealand
Kannaiyan Rabindranath, Waikato Hospital, Hamilton, New Zealand
Background: Persistent nephrotic range proteinuria is a widely accepted indication for kidney biopsy. However when the protein excretion rate is less than 3.5g/day and laboratory testing for systemic diseases (e.g. lupus) or a monoclonal gammopathy is negative, the indication to do a kidney biopsy is less clear
Aim: To review all kidney biopsies done at a single centre in patients with non-nephrotic range proteinuria (NNRP) to ascertain whether the renal histology resulted in a significant change in clinical management or unexpected diagnosis of a systemic disease.
Methods: All patients who had a kidney biopsy at Waikato Hospital between January 2011 and June 2015 with NNRP (Protein-creatinine ratio 3-350mg/mmol or albumin-creatinine ratio 3-260mg/mmol) and an estimated glomurular filtration rate (eGFR) of greater than 30ml/min/1.73m2 were included. Exclusion criteria were: acute kidney injury, rapidly progressive chronic kidney disease, hypoalbuminaemia, diabetes, a monoclonal gammopathy or serological testing suggesting an underlying systemic disease or viral infection.
Descriptive statistics were used to analyse clinical parameters, the renal histology and resulting changes in clinical management.
Results: Of 339 native biopsies screened, 109 biopsies were included. 62 were excluded based on the exclusion criteria. No patients were diagnosed with an unexpected systemic disease and 2 of 47 were commenced on steroids based on the renal histology. One of these patients had interstitial nephritis and the other IgA nephropathy.
Conclusion: In our study, performing a kidney biopsy in patients with NNRP and relatively stable renal function was unlikely to result in a significant change in management or identify a systemic disease that could not be detected through laboratory tests. This study will help inform physicians of the pre-test probability for a change in management resulting from a kidney biopsy in patients with NNRP.