Anyone who has donated a kidney has had a thorough assessment and kidney disease has been excluded. Their creatinine will be higher and their eGFR lower than it was before donation. For muscular men who have a pre-donation creatinine of 100-110µmol/l, or older male donors (>60 years) the post-donation creatinine may be as high as 160-170µmol/l. The remaining kidney will compensate by increasing filtration over time, but the degree to which this happens is variable. Younger donors will have great physiological reserve and therefore may return to 75% of pre-donation function, but older donors will not achieve this level. Since the younger donor should need their single kidney to last longer than the older donor this is entirely acceptable.
It is important to remember that those with a higher creatinine due to a disease process affecting both kidneys (i.e. they have chronic kidney disease) are very different from those with a higher creatinine because they have less nephron mass (understandable since half of the renal mass has been taken away but the other kidney is perfectly normal).
It is very distressing for living kidney donors if they are told they have chronic kidney disease, and are asked to return for repeated blood tests.
The following information is provided to the GP on donor discharge:
- “Additional blood tests will not be required, unless there is a clinical indication to do them as would be your standard practice for some other reason
We will follow-up with the patient closely over the next few weeks, and in the long-term review them annually
- Serum creatinine will be substantially higher and eGFR substantially lower than previously
A lower eGFR in this instance does NOT represent chronic kidney disease (we know the other kidney is perfectly good) but simply reduced nephron mass
There is a normal variability in serum creatinine (and hence eGFR) of at least 10% in everyone e.g. if creatinine is 130µmol/l then anything between 115µmol/l and 145µmol/l is really the same.
A lower eGFR therefore should not cause alarm unless there are other health concerns or it continues to decline. “
- It is perfectly possible to live for a long time with one kidney – the first ever live donor in NI donated at the age of 31 years in 1961 and lived in good health for 50 years and 4 months!
- Giving a kidney does not exempt the donor from all other health issues or illness that might occur in the course of their life. They may develop hypertension given how common this is in the general population, and although very unlikely they might develop a primary renal disease.
- There should be a low threshold for pharmacological management of hypertension in the setting of a single kidney. Very good rather than average blood pressure control is the goal for these patients.
- It is improbable that a live donor will have ‘normal’ renal function particularly the longer they live with one kidney. The expectation however is that the overwhelming majority will have adequate renal function (with no clinical impact) into their 80s.