Every UK lab report, whether it comes from your GP, a hospital, the NHS App or a private company, is built from the same five parts.
The test name
Often abbreviated. "U&E" is a group of kidney and salt tests. "FBC" is a full blood count. "LFT" is a group of liver tests. The same test can appear under several names on different reports.
Your result and its unit
The number only makes sense with its unit. Creatinine of 90 in umol/L and 1.0 in mg/dL are the same result. Reports from outside the UK often use different units.
The reference range
The span most healthy people fall inside, set by that laboratory for its own method. It can differ between labs, and with age, sex and pregnancy. The range printed on your report is the one that applies to you.
The flag
A letter such as H or L, or an asterisk, that the lab prints when a result falls outside its range. A flag draws the doctor's eye. It does not say why, or whether it matters.
The date
Most results drift a little from day to day. A run of results over months shows the direction of travel, which usually tells a doctor more than any single number.
These are the tests a kidney doctor looks at most often. Each explanation says what the test measures and why it is requested. None of it replaces a conversation with the doctor who requested your tests.
Creatinine
Creatinine is a waste product made by the muscles at a fairly steady rate every day. The kidneys remove it from the blood, so the amount left in the blood is a guide to how well the kidneys are filtering. The test measures the level in a blood sample.
Why it is requested. It is the most widely used blood test of kidney function and is part of the routine 'U&E' or 'renal profile'. Doctors also use it to calculate the eGFR and to keep an eye on the kidneys when certain medicines are being taken.
More about Creatinine: what moves it up or down
eGFR
The eGFR is not something measured directly. It is a calculation, made by the laboratory from the creatinine level together with the person's age and sex, that estimates how many millilitres of blood the kidneys filter each minute, scaled to an average body size. A higher number means more filtering.
Why it is requested. It is the standard way doctors describe overall kidney function in a single figure, and it is printed automatically whenever creatinine is measured. It is used to follow kidney function over time and to check that certain medicines are being taken at an amount that suits the kidneys.
More about eGFR: what moves it up or down
Urine albumin to creatinine ratio
The ACR measures the small protein albumin in urine relative to creatinine, which corrects for how dilute the sample is. It picks up tiny amounts of protein leak long before a dipstick would.
Why it is requested. It is the standard UK check for early kidney damage in people with diabetes or high blood pressure, and part of every kidney review.
More about Urine albumin to creatinine ratio: what moves it up or down
Urea
Urea is the waste product the liver makes when it breaks down protein from food and from the body's own tissues. It travels in the blood to the kidneys, which pass it into the urine. The test measures how much is in the blood at that moment.
Why it is requested. It is part of the routine 'U&E' kidney test and is read alongside creatinine. It responds quickly to changes in hydration and protein intake, so it helps doctors tell a short-term change from a long-term one.
More about Urea: what moves it up or down
Potassium
Potassium is the main salt inside the body's cells, and only a small fraction is in the blood. That fraction is tightly controlled by the kidneys and by hormones, and it matters for the electrical activity of the heart, nerves and muscles. The test measures the concentration in a blood sample.
Why it is requested. It is part of the routine 'U&E' test and is checked closely in anyone with kidney disease, heart disease, or taking medicines that affect potassium, such as water tablets and blood-pressure tablets.
More about Potassium: what moves it up or down
Sodium
Sodium is the main salt dissolved in the fluid outside the body's cells. Its level in the blood is controlled mainly by how much water the body holds on to, rather than by how much salt is eaten. The test measures the concentration of sodium in a blood sample.
Why it is requested. It is part of the routine 'U&E' test and is checked whenever someone is unwell, on water tablets, or has symptoms such as confusion, tiredness or muscle cramps. It is one of the most commonly measured tests in hospital.
More about Sodium: what moves it up or down
Bicarbonate
Bicarbonate is the body's main buffer against acid. It is regulated by the kidneys and by breathing, and its level in the blood reflects the balance between acid produced and acid removed. The test measures the concentration in a blood sample.
Why it is requested. It is printed on many U&E panels and helps doctors judge the body's acid balance, for example in kidney disease, diabetes, prolonged vomiting or diarrhoea, and in some lung conditions.
More about Bicarbonate: what moves it up or down
Haemoglobin
Haemoglobin is the protein inside red blood cells that carries oxygen from the lungs to the rest of the body. The test measures how much of it is present in a given volume of blood. A low haemoglobin is what doctors mean by anaemia.
Why it is requested. It is the main measure doctors use when they want to know whether someone has enough red blood cells. It is part of the full blood count, one of the most commonly requested tests, and is often repeated to follow a trend.
More about Haemoglobin: what moves it up or down
Phosphate
Phosphate is a mineral that, together with calcium, makes up most of the structure of bone and teeth, and it is also used by every cell for energy. Its blood level is set by the kidneys, the gut, vitamin D and parathyroid hormone. The test measures the concentration in a blood sample.
Why it is requested. It is part of the bone profile and is checked in kidney disease, in bone and parathyroid conditions, in people being fed after a period of poor intake, and when calcium is being investigated.
More about Phosphate: what moves it up or down
Parathyroid hormone
Parathyroid hormone is made by four small glands in the neck and is the main controller of blood calcium. When calcium falls, PTH rises and acts on bone, the kidneys and, through vitamin D, the gut to bring calcium back up. The test measures the hormone in a blood sample and is only meaningful when read alongside the calcium taken at the same time.
Why it is requested. Doctors request it when calcium is outside the range, to work out whether the parathyroid glands are the cause, and routinely in people with long-term kidney disease, where the glands commonly become overactive. It is also used when looking into low vitamin D, kidney stones and thinning of the bones.
More about Parathyroid hormone: what moves it up or down
This page is general education. It does not interpret your individual results and is not medical advice, a diagnosis or a treatment plan. Reference ranges vary between laboratories. Discuss your results with the doctor who requested them. If you feel very unwell call 999, or contact NHS 111 or your GP.
