I’ve got a solitary kidney, but do I have CKD?

A blog by Geraldine Fox, stage 3 kidney cancer patient and Kidney Cancer UK Trustee.

After I had a kidney removed 11 years ago due to kidney cancer, no one told me about the importance of kidney function. Thankfully, my remaining kidney has been brilliant in taking up the challenge alone, and I have gotten used to regular blood tests to check, and it is still doing a great job. Imagine my concern when, several years after my surgery, I suddenly saw on my online GP records that I apparently had Chronic Kidney Disease (CKD)! I knew I hadn’t been diagnosed with kidney disease, so why was it on my records? My mother had had kidney disease for many years, so I had more than a little awareness of the condition and its importance, but she had seen a kidney specialist for the diagnosis, and nothing like that had been raised with me.

I started doing some research and learned that kidney function is measured by estimating eGFR (estimated Glomerular Filtration Rate) using a formula which includes creatinine (a waste product), age and sex to calculate an estimate of kidney function. The levels are constantly changing depending on, among other things, how hydrated you are, so the measurement is only an estimate. It is also a snapshot that won’t necessarily be a reflection of the overall function of that kidney. So clinicians tend not to worry about the exact number but take a view of the trend over time. The normal eGFR for someone with two healthy kidneys is 90-100. So eGFR is an approximation of kidney output, not necessarily kidney damage.

Another test used for kidney disease, done alongside eGFR is a urine test for ACR (albumin-creatinine ratio), which checks for protein in urine and is an “important sign of kidney damage”6. ACR stages are A1, A2 and A3, with A3 being the most severe.

Therefore, it would appear that kidney function alone should not trigger CKD, but the combination of a low kidney function and signs of damage in ACR would do so.

CKD develops if a kidney structure is damaged in some way and it can’t function as well as it should. CKD stages based on eGFR starts at normal (stage 1 CKD if there are other signs of kidney damage). The NHS website clearly mentions signs of kidney damage as a determining factor for CKD 5 using eGFR combined with ACR in its table of kidney disease stages 5. The National Kidney Federation omits stages and describes kidney disease by percentages using less than 90 eGFR 6.

NICE guidance on the assessment and management of kidney disease 2 recommends testing for CKD for those with previous acute kidney injury such as having part of or a whole kidney removed. I don’t have any problem with being regularly tested for kidney disease 8 because there is a higher risk for anyone who has had kidney cancer and/or acute kidney injury 7. Kidney Care UK advice on the results of tests 8 says “If your eGFR stays above 60ml/min, and/or your ACR stays below 3mg/mmol, it’s likely your doctor will rule out CKD, as long as there are no other markers of kidney damage”.

At this point you are probably wondering what all this has to do with someone who has one healthy, well-functioning kidney and no signs of kidney damage? So did I! Why have I got kidney disease on my records when there are no signs of my remaining kidney having any damage, I just have less kidney tissue after nephrectomy?

My eGFR has been in the mid 70’s/60’s for over a decade, which is very good for one kidney, and with low ACR (0.6) Kidney Care UK thinks I should not be classified as having CKD, but the NHS has apparently classified me as having CKD anyway, rather than at risk of having CKD. Interestingly, my husband, with 2 kidneys, has an eGFR of 72, and yet he has not seen CKD on his NHS records. Many other nephrectomy patients have said they also have seen CKD on their records without explanation.

Patients like me who see CKD on their online records without any prior explanation can be caused unnecessary distress at a time when they are having to deal with the stress of living with or beyond cancer. It’s easy to think – why has no one told me about this diagnosis? What else are they hiding from me? It shatters trust and confidence in the medical team and causes worry and confusion. If medical teams included an explanation and specific information about the importance of kidney function to kidney cancer patients in documentation prior to nephrectomy, the importance of post-nephrectomy kidney function is more likely to be understood, and patients will have less unnecessary distress.

There are other elements to this apparently random use of the NHS system CKD classification. Kidney disease patients are encouraged to take statins to protect against cardiovascular disease, so if you are believed to have kidney disease purely because of the NHS classification, does this mean that you could be encouraged to take statins when you don’t have kidney disease?

In 2007 an article 1 was published suggesting that statins might have a preventative role which could reduce the risk of kidney disease for those most at risk. In 2022 a study 4 concluded that there was a “significantly increased risk of CKD post RN, especially in older patients”, and a 2016 8-year study 9 said that long-term use of statins “is associated with increased incidence of acute and chronic kidney disease.” However, the National Kidney Federation suggests that those on high doses of statins are more likely to develop kidney damage or even acute kidney injury 6. So it sounds like the jury is still out on whether taking statins purely to reduce the risk of kidney disease developing is worth considering.

A few years ago I was encouraged to take statins. After a discussion with a GP I agreed to start statins as my cholesterol was a bit high, but initially at a low dose on a trial basis to ensure that my kidney function wasn’t affected. I now ensure my kidney function is tested regularly so that any changes are identified at an early stage. However, I cannot find any NHS guidance on the use of statins as a preventative for kidney disease so clinicians and their patients may need to continue to take each case as it comes.

Another element is travel/life insurance – the need to declare all conditions during the quote stage is problematic for those of us with a CKD classification on our NHS records who do not have CKD. Declare it or not? If you declare it (because the insurer may want to look at your NHS records if there is a claim) we might have a higher premium for no reason. To not declare it might be seen as fraudulent if CKD develops during the insured period. A holiday after the trauma of cancer treatment is desperately needed for some patients at a time when they are having to deal with so many other issues is very far from ideal.

Patients are increasingly having to become their own advocates in their care. Once aware of the confusion, some patients have taken the initiative and asked for the CKD classification to be removed from their records, after it has been confirmed that they don’t have CKD, with varying levels of success. This involves taking up more time for both patient and surgery staff which could have been avoided if the CKD classification had been applied as intended, or patients had been informed of the classification in advance and the reasons for it – a real world example of an instance where better and timely information provision can reduce patient anxiety and surgery staff time needed to investigate the reason for the classification.

This blog is endorsed by Dr Ekaterini Boleti MD, PhD, FRCP, Consultant in Medical Oncology & RFL Acute Oncology Service Lead.

1 Effects of Statins on Renal Function
https://www.mayoclinicproceedings.org/article/S0025-6196(11)61418-3/fulltext

2 Chronic kidney disease: assessment and management
https://www.nice.org.uk/guidance/ng203

3 Cardiovascular disease: risk assessment and reduction, including lipid modification
https://www.nice.org.uk/guidance/ng238

4 The incidence and risk factors of chronic kidney disease after radical nephrectomy in patients with renal cell carcinoma
https://pmc.ncbi.nlm.nih.gov/articles/PMC6832851/

5 Stages of kidney disease
https://www.nhs.uk/conditions/kidney-disease/diagnosis/

6 How is kidney disease measured and divided into stages?
https://www.kidneyresearchuk.org/kidney-health-information/stages-of-kidney-disease/#:~:text=Glomerular%20filtration%20rate:%20GFR%20and,other%20evidence%20of%20kidney%20disease

7 The incidence and risk factors of chronic kidney disease after radical nephrectomy in patients with renal cell carcinoma
https://bmccancer.biomedcentral.com/articles/10.1186/s12885-022-10245-8#:~:text=Patients%20were%20followed%20up%20for,risk%20factors%20for%20postoperative%20CKD.

8 Tests for chronic kidney disease
https://kidneycareuk.org/kidney-disease-information/about-kidney-health/tests-for-chronic-kidney-disease/

9 Statin Use and the Risk of Kidney Disease With Long-Term Follow-Up (8.4-Year Study)
https://pubmed.ncbi.nlm.nih.gov/26742473/#:~:text=In%20conclusion%2C%20statin%20use%20is%20associated%20with,clinical%20trial%20populations.%20Published%20by%20Elsevier%20Inc.