The Assessing Long Term Outcomes in Living Kidney Donors (ALTOLD) was designed to understand the pathophysiological effects of kidney donation. This is important in assessing donor safety and for improving the understanding of the consequences of reduced kidney function in chronic kidney disease. Most previous studies of living kidney donors have been retrospective and have lacked suitable healthy controls. By including healthy controls, this study permits a better assessment of potential harms to kidney donors, and thereby provides important information for informing future donors and recipients of the risk of donation. ALTOLD was intended to be a prospective controlled study to better understand the effects of a mild reduction in kidney function from kidney donation in otherwise normal individuals.

ALTOLD successfully enrolled 200 pairs of living kidney donors and equally healthy two-kidney controls starting in July 2006, and measured iohexol glomerular filtration rate (GFR) and traditional cardiovascular disease (CVD) risk factors pre- and 6, 12, 24 and 36 months post-donation. Preliminary short-term results include the fact that GFR slopes increased between 6 and 36 months in donors versus controls, and that serum parathyroid hormone and uric acid levels have increased in donors versus controls. ALTOLD continues to answer important questions regarding the safety and the science of living kidney donation not addressed in previous uncontrolled cross- sectional studies.

The study aims to examine the pathophysiological effects of kidney donation, assess donor safety, and understand the effects of kidney donation on kidney function compared to healthy individuals.

The primary outcome of this study is the difference between donors and controls in the slope of the mGFR measured by iohexol clearance between 6 and 36 months after donations.

Secondary outcomes include medical history, vital signs, glomerular filtration rate, and other measurements at 6, 12, 24, and 36 months after donation.

Donors were any potential living kidney donor. Controls were any healthy individual who could theoretically be a donor at the study site. Both donors and controls had to be willing to give informed consent and be at least 18 years old.

Donors and controls were excluded if they were allergic to intravenous radiocontrast or seafood, had evidence of kidney disease (especially proteinuria), invasive cancer, active infection, cardiovascular disease, diabetes, and psychiatric disorders.

The study is still ongoing. However, preliminary results at 36 months show that GFR slopes increased between 6 and 36 months in donors versus controls, which suggests that kidney function continues to improve in donors while controls have expected age-related declines in function.