You hear about the kid who sold his kidney for an iPad?

This tragic story has been flying around the internet for the past few days. The story was broken in the western press by Reuters who described a 17-year old named Wang from Hunan who was paid $3,500 for his kidney which was subsequently sold for $35,000 to a patient in need of a transplant. The story originally surfaced last April (strangely his name at that time was reported as Zheng, but so many of the details line up I'm certain this is the same kid) but now that five people are being prosecuted and poor Wang is suffering from renal insufficiency the story is "hot" again. Apparently Wang will likely need a kidney transplant of his own soon.

The part of the story that irritates me is the implication that donating the kidney is the cause of Wang's failing kidney. This is implied and to the lay person it makes total sense. God gave you two kidneys. You better not donate one or you could end up needing a transplant yourself.

This is the wrong conclusion. Donating a kidney does not increase your risk of dialysis, transplant or poor quality of life. This is best illustrated in Ibrahim et al's retrospective study of 3,698 kidney donors from 1963 to 2007.

The study population was the entire cohort of living donors from the University of Minnesota. This population, prior to donating is free of diabetes, hypertension and had a GFR >80 mL/min. Additionally they had no albuminuria. Of course, many of them had a relative with ESRD.

Eleven of the 3,700  (0.3%) donors ultimately needed dialysis or transplantation. The average time from donation to ESRD was 22.5±10.4 years. Seven of the unfortunate, donated to a sibling and only three lost their kidneys due to the same etiology as their recipient.

...estimated incidence of ESRD in donors would appear to be 180 per million persons per year, as compared with the overall adjusted incidence rate of 268 per million persons per year in the white population of the United States.

Idea: to lower the epidemic of ESRD, get everyone to donate a kidney and we can reduce the incidence of ESRD by a third.

The remainder of the article goes through the deep analysis of the 255 donors who were invited for further testing.

• Creatinine had gone from 0.9 at the time of donation to 1.1 an average of 12 years later
• GFR went from 84 to 63 mL/min
• 11.5% developed microalbuminuria
• 1.2% developed macroalbuminuria

Thirty-eight donors have returned for two iothalamate GFRs at least 3 years apart. The investigators found the average loss of GFR was 0.6 mL/min per year.

One of the reasons that donating a kidney is safe is that the remaining kidney undergoes hypertrophy to accommodate the increased work-load. The investigators were able to provide some insight into the variables which govern this. Increased compensation correlated with:

• younger age at donation
• higher renal function at donation
• longer time since donation

This final graph should be the take away for discussing kidney donation:

Kidney donors report better physical and mental health than the US average.

When I counsel patients on the safety of kidney donation or medical nephrectomy I need to fight the pre-conceived notion that loss of renal function occurs nephron-by-nephron, so that losing half the nephrons through a nephrectomy halves the time to dialysis. People seem to visualize kidney function like a bathtub draining water. High blood pressure and proteinuria open the drain wider so the water drains out faster. Using that visualization, a nephrectomy is like losing half the water and putting you much closer to dialysis.

The image I try to paint is that losing renal function is like melting an ice cube, people start with two ice cubes. When the ice is gone the patient needs a transplant or dialysis. Poorly controlled blood sugars, high blood pressure and proteinuria turn up the ambient temperature so the ice melts faster, but it melts both the left and right cube at the same time.  A nephrectomy removes one of the ice cubes but it does not necessarily reduce the time until all the ice is gone.

The last point that needs to be made about this story is that shady, back-street organ selling scams are designed to line the pockets of the broker and surgeon. They do not have the best interest of the kidney donor in mind. The tragic outcome of young Wang is typical for these third-world, kidney-for-money scams. JAMA published a great article showing the typical experience in India a decade ago. It's still worth reading.

Thanks to Dr. El-Ghoroury for help with this post. Follow him on Twitter @melgho