Inflammation

High-sensitivity CRP (hs-CRP) measures very low levels of C-reactive protein in your blood, a substance your liver produces in response to inflammation anywhere in the body. While a standard CRP test detects the large spikes that accompany infections or injuries, the high-sensitivity version can pick up the subtle, chronic inflammation that simmers quietly beneath the surface and is increasingly linked to cardiovascular risk. Think of hs-CRP as a smoke detector for low-grade inflammation. Research shows that even modest elevations in hs-CRP are associated with a higher risk of heart attack and stroke, independent of cholesterol levels. This is why it is considered a valuable addition to traditional lipid panels: it captures a dimension of cardiovascular risk that cholesterol alone may miss. Generally, an hs-CRP below 1 mg/L is considered low risk, 1 to 3 mg/L is average risk, and above 3 mg/L is higher risk. However, readings above 10 mg/L usually indicate an acute inflammatory process (such as an infection or injury) rather than chronic cardiovascular inflammation, and should be retested once resolved. Levels of hs-CRP often respond to lifestyle changes. Regular exercise, a Mediterranean-style diet, maintaining a healthy weight, not smoking, and managing stress can all help bring levels down. Certain medications, such as statins, also reduce hs-CRP. It is worth noting that hs-CRP is a non-specific marker: it tells you inflammation is present but not where it is coming from. An elevated reading should always be interpreted in context with your other cardiometabolic markers and overall health picture. If your hs-CRP is outside the expected range, your GP can help determine whether it reflects cardiovascular risk, an acute illness, or another inflammatory process.

Creatine kinase (CK) is an enzyme found primarily in your skeletal muscles, heart, and brain. Its job is to help regenerate ATP, the molecule your muscles use as fuel during contraction. When muscle cells are damaged or stressed, CK leaks into the bloodstream, making it a reliable indicator of muscle tissue breakdown. For active people, CK is one of the most informative recovery markers available. It is perfectly normal for CK to rise temporarily after intense exercise: a hard weights session, a long run, or a competitive match can push CK several times above the resting range. This is a healthy part of the repair and adaptation process. The key is how quickly levels return to baseline: a CK that remains significantly elevated days after exercise may suggest you are not recovering adequately between sessions. Very high CK levels (typically more than ten times the upper limit) can indicate rhabdomyolysis, a serious condition where extensive muscle breakdown overwhelms the kidneys. This is rare but can occur with extreme exertion, heatstroke, crush injuries, or certain medications (particularly statins in susceptible individuals). Symptoms include severe muscle pain, weakness, and dark-coloured urine. Resting CK varies considerably between individuals. People with greater muscle mass tend to have naturally higher baseline levels, and Black individuals typically have higher CK than other ethnic groups, which is physiological and not a cause for concern. Mildly elevated CK in the context of recent exercise usually needs nothing more than adequate rest, hydration, and nutrition. Persistently raised CK without an obvious exercise explanation warrants further discussion with your GP. If your CK is outside the expected range, your GP can help determine whether it reflects normal recovery, overtraining, or something that needs closer attention.

Lactate dehydrogenase, commonly known as LDH, is an enzyme found in nearly every tissue in your body, including your muscles, liver, kidneys, heart, and red blood cells. This blood test measures how much LDH is present in your bloodstream and serves as a general indicator of tissue health and cellular turnover. Understanding your LDH level is useful because this enzyme is released into the blood whenever cells are damaged or broken down at a faster rate than normal. For people who exercise regularly, LDH can also act as a general recovery marker. It can give some indication of how much stress your training is placing on your muscles. LDH is involved in energy production inside your cells. It helps convert sugar into usable energy during a process called anaerobic metabolism, which is especially important during intense physical effort when your muscles are working hard and oxygen supply cannot quite keep up. Because LDH is present in so many different tissues, a raised level does not automatically point to one specific cause. Rather, it signals that somewhere in the body, cells are being broken down or turned over more quickly than usual. Think of it as a general alert light on your dashboard: it tells you something deserves attention, but further investigation pinpoints exactly what. Intense or prolonged exercise is one of the most common reasons for a temporarily elevated LDH, particularly after endurance events, heavy resistance training, or any session that causes significant muscle soreness. This kind of rise is usually harmless and settles within a few days of rest. Beyond exercise, dehydration, recent illness, certain medications, and even the way the blood sample is handled can all influence the result. Haemolysis, where red blood cells break down in the sample tube, is a well-known cause of falsely elevated LDH. If your LDH is higher than expected, especially if you have not exercised intensely in the days before the test, it is a good idea to discuss the result with your GP. They can look at it alongside other markers such as liver enzymes, kidney function, and your full blood count to work out the most likely explanation and advise on whether a repeat test or further investigation would be helpful.