Dr Lee said: “One of the main metabolites filtered out by the kidney is creatinine, a waste product produced from the breakdown of creatine.
“The kidney has a vital role in the body. Blood enters the kidney full of the waste products of metabolism, and the kidney tubules filter out these toxic metabolites, so they pass out in the urine.
“However, important substances such as other amino acids, glucose, hormones, and some types of medication, are reabsorbed back into the bloodstream.
“Creatine is an amino acid found in muscle, the brain, pancreas, liver and kidneys, and most of it is ingested in your diet, from red meat and seafood.”
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Your two kidneys filter 200 litres of fluid every 24 hours, so the way they function is vital for your health.
De Lee explained: “If your kidneys fail, you will need dialysis, where a machine does the filtration process for you, or, if you are lucky, you may receive a kidney transplant.”
How would you know if your creatinine levels are high or low?
Most people have very few symptoms in the early stages of kidney disease, and only 10 percent of people with chronic kidney disease know they have it.
Dr Lee said: “The most common causes of kidney disease are high blood pressure, diabetes, and having a family history of kidney disease, or being older than 60. “
Symptoms suggestive of kidney disease include:
- Tiredness and fatigue
- Sleep difficulty
- Dry itchy skin
- Peeing all the time – including getting up at night
- Blood in the urine
- Bubbles or foam in the urine
- Puffy eyes
- Swollen feet and ankles
- Poor appetite
- Muscle cramps
Dr Lee said: Anyone aged 40-74 is eligible for a free NHS health check. The dipstick shows up any abnormalities such as glucose, blood, or protein with a colour change on the stick.
“If kidney disease is suspected, for example, if there is blood or protein in your urine, your GP will arrange more blood and urine tests, and if indicated, an ultrasound scan of your kidneys.
“In due course, an MRI or CT scan may be needed, and sometimes a kidney biopsy.”