Kidney function declines with age and common causes of CKD, including diabetes mellitus and hypertension, are more common in older people. Age is an important consideration when diagnosing and investigating CKD. A 29-year-old presenting with an estimated glomerular filtration rate (eGFR) of 60 would warrant further investigation, however this eGFR would be within acceptable limits for a 75-year-old. Although further investigation may not be required, older patients may need medication doses adjusted to their level of kidney function. Because older people are likely to have fewer nephrons and less functional reserve they are at higher risk of acute kidney injury, and so nephrotoxic medication should be avoided where possible. Older patients may also be at higher risk of dehydration, particularly if they are frail or have dementia.