Yes, lupus can progress to kidney damage but it is quite rare, except in children.

The forms of lupus with a mainly cutaneous and articular onset are common. They cause skin damage and joint pain. These forms, if treated quickly and sufficiently (usually with synthetic antimalarials {hydroxychloroquine, chloroquine}, cortisone in small doses for a limited time and if necessary with added methotrexate in addition to the previous treatment) possibly may never be accompanied by other disorders.

The occurrence of kidney damage, if it does not exist initially, is rarer after several years of evolution. However, it should be looked for regularly by a urine examination because the renal damage from lupus does not initially cause any symptoms, including no kidney pain. Black-skinned patients and Asian patients are more prone to developing a kidney complication.

Renal involvement of lupus results in inflammation of the kidney that leads to the appearance of proteins in the urine (albuminuria or proteinuria) and / or red blood cells (hematuria). The search for albumin and blood in the urine is more frequently done in children than in adults. It can easily be done by your GP or in the hospital using instant tests, in the form of strips that are dipped in urine. This is a very sensitive screening examination that should be done at least every 6 months, and sometimes much more often at the beginning of the disease, especially when there is a high level of native DNA antibodies or a decrease in complement. Proteinuria analysis performed in the laboratory on a urine sample or on 24-hour urine are more accurate.

So, if the search for albumin and/or blood is negative on the strip, it means that there is no significant kidney damage. If the examination is positive, it is first necessary to check that the presence of protein and / or blood is related to lupus by a biological examination of the urine. Indeed, a banal urinary tract infection, or a poorly done urine collection during menstruation can also make the test positive. If the presence of albumin and / or blood is related to lupus, your doctor will suggest a kidney biopsy, usually performed by puncture under local anesthesia and ultrasound tracking. Two millimetric fragments are taken from the same kidney, and analysed under a microscope. In case of anticoagulant treatment, the biopsy can be performed through a vein in the neck with a guide that goes down to the vein of the kidney to take the samples (transjugular biopsy) limiting the risk of bleeding. In both cases, the kidney biopsy is usually not a very painful examination (apart from the inconvenience of local anesthesia), since there are no nerves inside the kidney. There is a low risk of renal hematoma after the biopsy.

This essential step will enable the analysis of your kidney under a microscope and determine the magnitude of kidney damage.

Since the kidney damage is diffuse, i.e. spread over the entire kidney, a biopsy of a few millimetres provides information on the overall condition of the 2 kidneys.

The presence of albumin in the urine during lupus may be the result of mild kidney involvement, which may not damage the kidneys, or of severe damage that can lead to kidney failure in the absence of effective treatment. Kidney biopsy is therefore fundamental to guide treatment.