Blood London has been offering Urea and Electrolyte Blood tests on a self-referral basis to patients in Greater and Central London for over 20 years. You can walk into our clinic on weekdays from 9 a.m. to 6 p.m. and from 10 a.m. to 2 p.m. on weekends for your blood sample collection. Our experienced healthcare professionals use some of Europe’s well-known and fully equipped labs.
Please note that when you order a blood test on a self-referral basis, we will send your lab report without comment or note from our doctors. This service is only available for patients under our doctors’ care.
If you need a consultation, further testing or treatment after your test results, contact our clinic, and we will happily help.
A urea and electrolyte test usually detects blood chemistry abnormalities, dehydration and kidney (renal) function. This test checks for electrolytes in the blood, such as magnesium, potassium, and sodium (salt).
If the electrolyte levels are too low or high, abnormal heart rhythms may occur, so ensuring they are within the normal levels is important.
The body produces a protein called urea, which the kidneys break down. If urea levels in the blood are higher than normal, it may indicate kidney function problems that may also affect the heart.
Some heart medications, like ACE inhibitors, can also affect the kidneys, so this test can help your doctor decide if the medication is safe and if increasing your dose is necessary, depending on your condition and test results.
The urea and electrolyte test is a blood test requiring only a few millilitres of venous blood sample. In newborn babies, the blood sample collection is from a heel-prick sample.
Urea and electrolyte test helps confirm if the kidneys function properly and rule out significant imbalance of biochemical salts in the blood. A U and E test can detect several conditions because each test parameter can give a low or high result. These conditions include:
Each of these conditions also have several possible causes.
For BUN or urea:
For carbon dioxide (CO2):
For chloride (Cl–):
For potassium (K+):
For sodium (Na+):
Considering other factors while interpreting abnormal test results is important. Generally, one higher or lower value without other information cannot give an accurate diagnosis, but certain exceptions apply.
Simple everyday things like drinking less or more than usual, diet, sweating, medications and exercising may change your test result. Pregnancy can also cause changes in test results. It is best to have your prescribing physician or GP evaluate your test results as they know the reason for requesting the test. They also have access to past results, understand your anamnesis and have other information to make informed conclusions.
Blood urea nitrogen (BUN) may be higher than normal in renal failure, including acute and chronic kidney disease, dehydration, urinary tract obstructions, burns, shock, dehydration, gastrointestinal bleeding and when taking certain medications like antibiotics and high-protein diets.
BUN may be lower than normal in hepatic failure, including chronic and acute liver disease, overhydration, nephrotic syndrome, and low protein diets.
Carbon dioxide (CO2) may be low in severe vomiting and diarrhoea, aldosteronism, alkalosis, emphysema, or when using certain medications like hydrocortisone, aldosterone and some diuretics.
Chloride (Cl–) may be high (hyperchloremia) in hyperventilation, metabolic acidosis, respiratory alkalosis, hyperparathyroidism, dehydration, Cushion syndrome, excessive normal saline (NaCl 0.9% solution) infusion, and when using certain medications like chlorothiazide, androgens and oestrogens.
Chloride (Cl–) may be lower than normal (hypochloremia) in overhydration, metabolic alkalosis, Addison disease, diarrhoea and vomiting, respiratory acidosis, burns, salt-losing nephritis, congestive heart failure and when using certain medications like diuretics and corticosteroids.
Potassium (K–) may be elevated (hyperkalemia due to excessive dietary intake, crush syndrome, acidosis, kidney failure, hypoaldosteronism), infections, and when using medication like antineoplastic drugs, lithium, potassium-sparing diuretics and antibiotics.
K+ may be lower than normal (hypokalemia) in Cushing syndrome, insufficient dietary intake, hyperaldosteronism, burns, diarrhoea and when using medications such as laxatives, diuretics and insulin.
Sodium (Na+) may be elevated (hypernatremia) may be elevated due to excessive sweating, vomiting and diarrhoea, diabetes insipidus, hyperaldosteronism, diarrhoea or when using some medications like oral contraceptives, antibiotics and anabolic steroids.
Na+ may be lower than normal (hyponatremia) due to Addison disease, kidney disease, diarrhoea and vomiting, heart failure, excessive water intake, burns, sweating, insufficient dietary intake and when using some medications like tricyclic antidepressants, diuretics and ACE inhibitors.
Critical values indicate a medical emergency requiring immediate attention, which may indicate life-threatening implications. U and E critical values include:
You can get a urea and electrolyte test at Blood London. Visit us today for your U and E blood testing, or call 020 71830244 to book an appointment for your test.
Select the test that you would like to undergo
Go to the Harley Street clinic for your blood draw and pay for your test in person
As soon as the results are ready, the will be sent to you by your chosen method
