After 65, staying active and independent tends to matter more than any single number. Blood tests after 65 can support that goal by keeping an eye on a few areas that change with age: how the kidneys filter, whether vitamin B12 is keeping up, and the calcium and vitamin D that bones rely on. This guide explains what three tests in our catalogue measure and why age changes how their results are read.
Kidneys: a slow change with age
The NHS describes chronic kidney disease as a common condition often associated with getting older, and notes that there are usually no symptoms in the early stages. Often it only shows up when a blood or urine test is done for another reason.
At the same time, kidney function also falls with healthy ageing. A review on kidney assessment in older people explains that a lower filtration rate is common in this age group and may reflect normal ageing rather than disease, especially when there is no protein in the urine, and calls for a more nuanced reading of results (Muzaale et al., 2024). That is why one result outside the adult range is a starting point for a conversation, not a conclusion.
Liver and Kidney Function Test
This test brings together 12 markers in the LML list. For the kidneys it measures urea, creatinine and eGFR, an estimate of how well the kidneys filter. For the liver it measures ALT, AST, alkaline phosphatase, GGT, bilirubin, albumin, globulin and total protein, and it also reports sodium. The LML notes that it is often used to check the effects some medicines have on the liver and kidneys, which is relevant for many people over 65. It can be done with a finger-prick sample or a sample from a vein.
Vitamin B12: common and easy to miss
A review on vitamin B12 in older adults describes the deficiency as common in this age group and often missed. Low levels are associated with cognitive decline, low mood, balance problems, sarcopenia and frailty, and symptoms often overlap with other conditions (Papazachariou et al., 2026). Another review lists older age, some medicines such as metformin and proton pump inhibitors, and limited dietary intake among the risk factors (Patel and McGuirk, 2025).
The NHS adds that pernicious anaemia, an autoimmune condition that stops B12 being absorbed, is the most common cause of B12 deficiency in the UK, and that it is more common in women around 60.
Vitamin B12 (Active)
Our catalogue includes Vitamin B12 (Active), which measures active B12 rather than the total B12 of the standard Vitamin B12 test. The review above notes that standard serum B12 assays have limited sensitivity, which is one reason active B12 is sometimes chosen. Your doctor can advise which measure suits your situation.
Bones: calcium and vitamin D
The NHS explains that losing bone is a normal part of ageing, that women lose bone quickly in the first years after the menopause, and that osteoporosis often goes unnoticed until a bone breaks. The LML explains that vitamin D helps the body absorb calcium properly, and that calcium is essential for strong bones.
Calcium + Vitamin D
This test measures calcium and 25-OH vitamin D in one sample. The LML notes that it is often considered for people with bone pain, muscle weakness or repeated fractures. It is worth knowing its limit: a blood test does not measure bone density. The NHS explains that bone density is assessed with a bone density scan.
What about iron?
Iron and red cells also deserve attention with age. The LML lists tiredness, shortness of breath and paler skin among the effects of iron deficiency anaemia. For a combined view, the panels described in our articles on yearly check-ups include a full blood count and iron studies.
